Convergent Series

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Archive for the ‘Technical Details’ Category

Silver Metal Clay on Pottery

Posted by C Scheftic on 2017/02/22

For reasons I’ll explain at the end, here are a few examples of pottery I’ve made over the past few years to use in some of my early experiments in adding silver metal clay decorations to them.  Since I’m showing here my first experiments with various techniques, for those I chose to not risk my best pottery pieces and the decorations were deliberately kept very simple. But each of them does seem to have a little story to tell!

  1. I threw, bisqued, glazed, and fired these pieces.  The same electric kiln was used for both firings.  The relatively rough glaze was a deliberate choice … I then smushed some clay onto the surface and fired that with a creme brulee torch to sinter the silver.  For my first-ever attempts at these, I was happy with these results.
    Two Bowls with Fine Silver Silver
  2. I threw several pieces, cutting ridges into their outside surfaces. After bisque-firing those (in a different electric kiln), I glazed the inside and smushed silver clay onto the outer ridges, then fired those (in a gas kiln).  Most turned out wonderfully, and I’ve already sold all of those but the one shown here.  Part of the back of this one did break off. (I used the same glaze inside this one as on the piece in item #3, below.) The fault could have come from either a flaw in the pottery (perhaps I’d cut a ridge a little too deeply?) or because I’d applied the metal clay a bit thicker there (and the shrinkage as the binder burned off and it sintered was too much for the pottery clay), or even from both of those combined… I haven’t yet gotten around to trying to distinguish among those possibilities.
    Bowl with Fine Silver (glazed inside, silver outside)
  3. I threw, bisqued, glazed, and fired this piece.  (Those firings were done in the same electric / gas pattern as #2, above.)  Then I rolled out some “snakes” of a low-shrinkage silver metal clay and spread a tiny bit of overlay paste onto them (in the setting where I made this–not my own studio and I’d forgotten to take a tiny paintbrush for this step–that was far easier than applying paste to the pot). I pressed those onto the vase, and fired this piece yet a third time (and in yet a different electric kiln, a small one that another artist had for firing metal clay molds).  The clay shrank: the upper snake held at the ends but cracked open at roughly 1/4 of the way from one end; the lower one held along its length but pulled up into itself leaving a little smudge of silver paste at the end and at a few places along its side. The little “splats” of silver must have been a bit of clay/paste from my fingers as I was sticking it all together. I didn’t notice those until after the firing, but I really like that accidental result. Now I want to figure out a way to reliably recreate those, especially like the one above and to the right of the top snake!
    Pot with Fine Silver
  4. I threw this piece and bisque-fired it (in an electric kiln).  I applied glaze to the outside.  I rolled several “snakes” of a low-shrinkage metal clay, wet them on the bottom, and applied them in a “spray” pattern to the unglazed inside bottom and edge.  The piece was fired in a gas kiln.  When removed, the silver looked sintered and the patterns were all still intact.  The piece was immediately (i.e., still hot!) dropped into a newspaper-filled can, and covered.  (Those who know the process will recognize that as a “raku” firing!)
    Wide Bowl with Fine Silver (balled by raku)
    This outcome was my biggest surprise! The gas kiln did not over-fire the silver, but the fire from the raku-process did then get the inside of the can hot enough to completely melt the silver!  You may just be able to see some faint hints of where part of the pattern had been: tan spots where some of them were even show little trails of tiny silver balls.  But most of it pulled up into two balls in the center! (Another small bit from the edge must have just fallen off in the raku-can and disappeared as it was emptied out. That’s experimentation!) I was able to get a number of pieces with ball-decorations to survive the raku process (similar look to both #1 and #2 above) and turn out beautifully, but I have yet to figure out how to approach, in raku, designs like those that later developed from the technique I first tried with #3.
  5. While I’m sure that many readers with metal clay experience will have taken their clue from the size of the silver balls and snakes above, I will end with another little pot from that session.  The pencil is there to give you a sense of scale for all these pieces! And if you look carefully, you should be able to see the small (3 mm) clear cubic zirconia I’d set into the wet clay.  All the ones I made with those did survive all three firing steps (bisque and two-part raku).
    Green Crackle Pot with CZ
    While the previous items all show my very first attempt at each technique, this was my second try. The very first piece did have one very tiny crack just off to the side of the CZ, visible but with no obvious damage to the structure. That was probably due to my having used too-wet clay until I figured out that I could set CZs in stiffer clay. That bowl did have a great shape, and another artist really wanted to swap me some art-glass for it!

I’ve been playing around with miniature pottery, off and on, with and without such embellishments, for several years now. Though I have been offering my miniature pottery for sale at various shows, I haven’t taken the experimentation seriously enough to feel inclined to write much about it. (And I’m not teaching this, at least not yet, so I don’t have that inspiration for writing about it either…)

But I decided to post these examples after seeing some experimentation that Terry Kovalchik has been doing, and writing about, with painting silver clay paste onto pottery shards, and reading some of the reactions he’s gotten to that in the Metal Clay Now group on Facebook. (Metal Clay Now is a “closed” group, but readers of my blog who use Facebook are certainly welcome to ask to join it!)

While many of his results are superb (as usual!), Terry has reported some further breakage of the clay shards during the sintering process. But, like my #2 above, that could be from any or all of: a weak spot in the pottery (at initial construction or from whatever created the “shards”), the shrinkage of the silver clay (how thickly or how evenly it’s applied, exactly how it aligns with any weakness in the clay body), or any number of other little peculiarities. So I thought it was time for me to bring out a few of my explorations too, and maybe others will start to chime in with what they’ve tried and how it’s worked out for them.

If you are working with similar combinations, please leave a comment: I’d love to hear from you, see some of your results, and compare more notes!

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The evolution of two “old favorite” classes!

Posted by C Scheftic on 2016/07/21

It’s time to follow up on an earlier statement, and write a little bit about some upcoming classes. But since this is (what is often called in social media circles) Throwback Thursday, I thought I’d include a few notes on how the ideas and directions for two popular sessions have evolved over time, since I’m repeating them on a couple of Saturday afternoons this month (soon!) and next.

Reversible Draped Silver
Saturday, July 23, 2016 from 1:00 PM to 4:00 PM (EDT)

I must admit that the idea for this came from Hadar Jacobson. I’ve made pieces, and then been asked to teach classes, using both precious metals (silver) and base metals (bronze, copper, steel).

We texture the clay and then roll it thin in order to get it to drape nicely. With .999 fine silver, that produces pieces that seem to me to be a bit too fragile, risking bending or breaking at the thinnest points. We can solve that problem by adding a backing layer, or at least a frame, to provide additional stability.

When we use base metals (like these in bronze and copper), we get pieces that are a bit harder. Thus, most of our pieces can just be folded and embellished. They rarely seem to require extra layers for sturdiness, though of course those can always be added if desired from a design standpoint.

I will admit that I never tried making these with .925 sterling silver: I don’t particularly like fussing with the firing schedule for that clay, and have only used it for a handful of different designs. But last winter I started making these with .960 sterling which is much easier to fire than is the .925 form, and they turned out great. So that’s what we used the last time I offered this as a class, and it’s what we’ll be using again this week.

At this point, we’ll still be using “homemade” .960, that will come from mixing .999 and .925 clays. There is a commercial version now available, EZ960, that’s recently been released. We won’t be using that here simply because I haven’t yet had enough time to experiment with that to feel as comfortable as I’d like using it in a class. I want to learn any and all potential pitfalls with it myself before foisting it on a room full of students! Stay tuned for news in that arena.

Reversible Woven Silver
Saturday, August 27, 2016 from 1:00 PM to 5:30 PM (EDT)

Three Woven Silver Pendants (Class Samples)The way I began to make these pieces, and lead students in making them, has had a number of inspirations. Hadar, again, was one of them, but so were CeCe Wire, a project in the RioRewards certification program, plus a whole range of others (such as some of Mary Hettmansperger’s metal-weaving projects).

Sometimes, as in the silver pieces above, the weaving would be the main element in the design. Other times, as in the mixed-metals piece shown next, the woven portion is more of an accent to another important part of the design. Because of the thin nature of the strips used in the weaves, however, I always made sure that their ends were securely tucked into a frame.

Ahh, but do you remember the .960 silver I just mentioned above? Yes! While I’ll still guide students through some dos and don’ts in letting small ends hang out, we can now be far more adventurous in allowing that. We no longer need to be completely constrained by framing. Again, we can use solid frames if we want that in our designs, but it’s now an option, not a requirement. This class is going to be another one that’s lots of fun!

If you’re in the western PA area, or can get here for one or both of those dates, I hope you’ll join us!

Please note: The links in the title of each session above take you to the site from which you can reserve a seat at that particular class. In each case, the materials provided will be enough to make an interesting pendant. If you want to divide it in half and make earrings instead, that’s fine with me. If you want to buy a bit more material and make something big or even (if you find yourself so comfortable with this material that you are able to work quickly enough to…) make both a pendant and a pair of earrings, that’s yet another option.

Also: I’ve got two other workshops coming up this summer, both of which are multi-day events. I’m hoping to write about those soon too, but the ‘net access in my studio is getting increasingly less reliable (we’re hoping for a fix next month…), so I’m struggling to keep up with online announcements. But you should know that all my workshops at The Artsmiths of Pittsburgh are announced on the Eventbrite system. If you are interested in a specific class but for some reason can’t make it on the given date(s), please let me know. I’m happy to repeat any of my sessions on another date, whether it’s back at Artsmiths again, in my studio, or at another site.

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And now, my original reason for taking the photos with my last post….

Posted by C Scheftic on 2016/01/17

I may to have to try to do this again in the summer, when the natural lighting situation is better, because I don’t think these photos tell the tale as distinctly as I’d hoped. But this is one thing I’ve been experimenting with over the past week…. The point is to look at the difference in the color (and size) of the silver pieces at different points in their process. (Next time, instead of trying to capture so many, I think I’ll try to focus specifically on just one or two, with close-ups.)

But here is a shelf-load of pieces, ready to go into the kiln. They don’t look silver-colored at all, do they, even though they are at least 90% silver! Next time, I’ll try to burnish one in the clay-state, to try to show that the silver really is there, but for now:

And here we have that same shelf-load of pieces, after being fired, when the shelf had cooled just enough to safely remove it from the kiln. Note the “white” color of these pieces: this is normal for just-fired metal constructed from silver clay. Comparing this to the previous photo, you can also get a sense of the shrinkage that took place.

And here is that same shelf-load of pieces, after having been run through either a rotary tumbler (with mixed-size and -shape stainless steel shot) or a magnetic finisher (with tiny stainless steel pins). I need to work on the lighting for each of the different versions (and I really struggled with the meager equipment I have to get all of the shined-up ones together without too many shadows or too much glare!), but I hope you can see that they are, at last, starting to look like silver!

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One more thought on using my tumbler…

Posted by C Scheftic on 2016/01/15

Well, it’s about time! Last night, I finally took two minutes to figure out how to “publicize” a blog post on Facebook. (That time was split between finding where the settings were and choosing among the options available.) And I used that feature for the first time with my last post. This morning, I found the following exchange over there:

Now, Alice is correct. So I could have just “liked” her comment but, well, I admit I don’t know how to be terse, and I thought it was worth trying to be clear about what was going on, for anyone else who might stumble across the discussion here. So I decided that another blog post was in order. Once I’ve got it ready, then I’ll go “like” her comment and share this post too.

This is what my rotary tumbler looks like when I’m ready to use it:

There’s a brown paper bag folded in thirds and stuck under one end. Why?

Well, I don’t think it’s specific to this style of tumbler, though it may be a bit more common with these than with some others. But I discovered this trick with the very first tumbler I ever used: a little, all-plastic, undersized for its intent, rock tumbler for kids. The key is that the barrel has to be in good contact with both rollers, both of which have to be able to turn smoothly.

In an ideal setting, the base would be flat on a table. The motor would turn and the belt attached to it would turn the roller in the middle of the base. That would turn the barrel. Because the barrel is also supported by the other roller–the one at the end–that one would turn too. Thus, the motor, belt, both rollers, and the tumbler would all roll around together.

But, with this particular unit, if I simply put the base flat on the table and set the filled barrel on it, then the roller in the middle–the one that’s driven by the motor–that one turns just fine. That’s my clue that the “belt” connecting it to the motor is adjusted correctly. (If that roller slips, or seems to stick, that’s a sign that the belt needs to be adjusted which, for the record, is a routine maintenance task.)

In my case, however, this barrel would just turn in fits and starts. The “other” roller turns only when the barrel turns, so it’s not helping either. It seems to me that there are two possible solutions (though I do welcome other informed suggestions…):

  1. Slightly raise the end with the motor on it. This pushes the barrel onto the roller at the “end,” which forces that one to move along with the barrel.
  2. Slightly aise the end opposite the motor. This pushes the barrel onto the roller in the “middle,” which reduces the role of the one at the outside end.

I’ve tried it both ways and, in fact, both seem to work. But, as shown in my photo, above, I tend to set things up the first way, so the end with the motor is just slightly higher than the other end. In my logic, the second way seems like it’s putting extra pressure on the motor to do all the work. The first way seems to force both rollers to contribute to the effort, and that’s why I prefer to set it up that way.

If you have any other suggestions, or a better way to explain what’s going on here, please contribute to the discussion via the comments below!

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I love my clear plastic hexagonal tumbler barrels!

Posted by C Scheftic on 2016/01/13

An art-jewelry-friend of mine, Zoe Nelson, posted this in a metal clay group on Facebook last week. But I check Facebook only sporadically, so I didn’t see it until a day and a half later, by which time she’d already received dozens of suggestions and found a neighbor whose car-repair tool (an oil filter wrench) actually helped to solve the problem.

Until then though, none … none! … of the suggestions were how I would have responded: a few were halfway-decent alternatives, a few were complaints rather than solutions, some were simply sympathetic notes, and the rest were ideas that were far more complicated than I’d’ve thought necessary, a few even likely to damage the barrel. Thus, this blog post, at last, that Zoe knows I’m writing for her (and any others in a similar predicament!) to have for future reference.

I did make a range comments about my tumbler that uses these barrels, and more, a few years ago. (Looking for the link — gosh, that was way back in 2012!) So I have over three more years experience with it since then.

Yeah, the clear plastic lid can be a bit tricky. But (just as Zoe said in her Facebook exchanges with her readers) I’ve had as much trouble, in different ways, with the lid on the kind of barrel that’s made out of black rubber. While your experience may differ, I will take the clear plastic ones any day!

You can follow the link above to read the pros and cons I wrote back in 2012 (and see a few more photos, plus other alternatives, if you landed here without a lot of knowledge of tumblers), but here are the things I want to say now that relate specifically to Zoe’s problem and anyone else who may encounter a similar one.

First of all, let’s try to prevent the problem from the start:

  • After you’ve filled your barrel with shot, water with either a bit of dish soap or burnishing compound, and the pieces you want to tumble, do this: Dip your fingertip in the liquid and run it around the rubber ring that seals between the barrel and the top. You don’t need to soak it, just get it slightly damp. This seems to help it form a good seal.
  • Then put the lid on and turn it backwards until it feels like it is seated correctly and fits smoothly. (I don’t do this all the time, but if it seems to stick at all at the next step, then I always back up and do this!)
  • Turn the lid forward to tighten it. It should turn smoothly and freely: if it doesn’t, stop! If you have trouble getting it on, you will have more trouble getting it off! It should tighten easily. If it’s catching, it’s not seated correctly. Back up a step, and repeat that one and this until you get it to close up easily.
  • Then, tighten it a bit more so that it seals. The lid does need to be tight, but not super-tight. Tip the barrel sideways and turn it around a couple of times (like it will turn on the base), and see if it leaks.

    • If it doesn’t leak, proceed to start tumbling.
    • If it does leak, try to tighten it a little bit more and repeat the test. (If there is some liquid in the little “gaps” in the big part of the barrel, where the straight edges connect to the rim, that might be all that’s leaking. So test it for a bit longer and see if it stops dripping once that has emptied out.)
    • If it continues to fail, don’t over-tighten it! Spin the lid backwards and, if it moves smoothly, go ahead and try to re-tighten it. If it doesn’t move smoothly or still continues to fail, just take it off and start from the first, seal-lubricating step above (checking to see if it may be time to replace that rubber ring).
  • When you’re done tumbling, the lid should come off…. It may take a bit of effort (you did have it sealed up well, you know, so it wouldn’t leak!), but set it down flat on a table, hold the barrel, and figure out how to push down (to press against that great seal you managed to make) and turn the top, let up and turn if you can, push a bit more if necessary and keep trying to turn, until it starts to move.

Now, if that last step doesn’t work, ignore all the suggestions about things like cooling the bottom while heating the top, or hitting the edge of the lid with a knife, or trying to pry the lid off, or any of the other tricks that people have tried in their kitchen, and use the method that I always use in mine and which has always worked on my clear plastic tumbler barrels too. I will quote it directly from the funny but still useful book by John and Marina Bear that is illustrated to the right (just so you get an idea of what the whole book is like, in addition to the tip on what to do…):

Problems with Utensils
Stuck bottle or jar tops

H. Allen Smith revealed to the world the technique for opening all screw-top containers. Now there are untold millions of us who face Mount Kisco or wherever it is he lives and say thank you every time we are faced with an obstinate top.

The technique: Bang the top flatly on a hard surface, like the floor. Not the edge, but the flat surface of the top. Just once. Hard. That’s all. And to think of all those jars we used to hold under hot water.


(Not that I want to date myself here, but I found that book in what must have been just a few months after this version was published. I have the 1973 UK edition: that’s the year I moved there — my second real full-time job after college — and I suddenly found myself cooking in a somewhat different kitchen using a number of unfamiliar local ingredients, and in London at that time there was a waiting list of over a year and a half to get a phone installed! (I was there for only two years, to the day! So I never even applied to the waiting list. We had postal service twice a day, and lots of people I knew didn’t have a phone either: we could simply write letters back and forth to make plans for the evening! But I digress…) Transcontinental phone calls back then would have been way too expensive anyway… so I had no way to call my family or old friends for help and there were times when I just wasn’t ready to admit to my new English friends some things that tripped me up. The book was a hoot — written by former New Yorkers living in the UK — so although it did use the British terminology I was just beginning to learn, the attitude sometimes felt familiar. And it was helpful too! People seem to either love or hate that book, and I’m one of the former….)

Anyway, there may be a few “bad” clear plastic tumbler barrels out there (and others that have been damaged by mis-use) that are harder to tighten, and those will also be harder to open. But I have two myself: one marked A for the Latin Argentium aka silver (or other precious metal) pieces, and the other, marked B, for pieces containing any form of Base metal. I’ve used a few others at meetings or workshops. I’ve seen people struggle to get them to seal and I’ll admit I struggled with mine the first few times I tried to use them, until I got a feel for it. Like riding a bike (or rolling out metal clay) once you "get" it, it seems easy!

And, every time I’ve had a problem closing any of those barrels, I’ve just loosened the lid, spinning it backwards until I’m sure I’ve got it seated right, and closed it back up with little difficulty. If I tighten it just enough to get a seal (and even that does take a bit of practice to get the feel, but it will come if one remains calm and pays attention), it may take a bit of oomph to get it to start to open, but it will come loose again. Or, if it does resist, just use the tip above: lid down, flat, once, hard.

Because we do need to be able to retrieve our beauties once they’ve completed their tumble-burnishing, don’t we?!!

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Flexible Greenware, or What Metal Clayers Mean by Flexible Clay….

Posted by C Scheftic on 2014/09/19

There’s a lot of “buzz” today in the Metal Clay community: Mitsubishi has just released a new fine silver product they’re calling PMC Flex. Well, it’s been available in Japan for a couple months now; the rest of the world is able to order it starting today with, I’ve heard, shipping to commence on Monday. I was lucky enough to get my hands on some of it just this week, so I haven’t had the months of experience with it that some of the official “early testers” have had, but I wanted to report my very first reaction….

First, though, some background. I’ve been working with clays that remain flexible after drying almost as long as I’ve been working with metal clay. I will say, that I find the term “flexible clay” to be a bit confusing: all clay is flexible when you’re working with it! The ones I’m going to talk about today are the ones that remain flexible, that do not get really hard, until they are fired in some way.

Three Woven Silver Pendants (Class Samples)The center pendant in this group of three (photo, left) was one of the first pieces I ever made this way. It was after I’d used some clay at an event where I gave repeated demos, working and reworking it, exposing it to oil (so it wouldn’t stick to the textures I was using with it), adding water (to replace what had evaporated during use, but also risking the washing away of some product, silver and/or binder). By the end of the day, the clay had gone rather funny: it wasn’t acting like clay at all. It had gone from sticky to slippery. It didn’t leave bits stuck on tools or hands but it did sort of slime everything it touched. Was it destroyed? I had no clue. In the very first class I took, I’d been taught that you could extend the working time of clay by adding a very tiny bit of glycerin, but one should take care to not add too much. (And … I later heard that same instructor say she no longer recommended doing that.) I’d read in some online group that you could “revive” clay that had gone “off” by adding a bit of glycerin to it. I’d also heard or read somewhere (in a class? online? this was years ago now..) that you could make clay that would remain flexible after being allowed to dry if you added a good bit of glycerin. No specifics. Nothing about how much, or how one should do it, or just what would happen if you added too much (other than, obviously, thinning the silver out so much that it could not sinter in the kiln). There were just vague comments. Questions I’d seen about such details had remained unanswered. But … I had some glycerin on hand: what more did I have to lose beyond this clay that was unworkable? Why not try it? And, while at it, why not try to go the whole way?

I added some to the wad of muck I had. I kneaded it in. It went even more funny, and not in a humorous way: by then it was falling completely apart. I tried to not panic. I attempted to knead it some more, and it seemed to start getting better. I kneaded a bit more, and worked a bit of water into the clay too. I began thinking this might work, after all, so I rolled it into a neat ball, wrapped it up air-tight, and went to bed, hoping that would all soak in better with time. The next morning, I took the clay out of the plastic, and it seemed much more workable. It didn’t feel like clay fresh from a new pack, mind you, but I could roll out a couple small pieces and texture them. I let all that air dry while I did whatever all else it was I had to do that day (years and years ago now). When I got back to it that evening, it was wonderful: dried out enough that didn’t feel like I could smash it with clumsy fingers, but still soft and pliable enough that I could cut it with scissors and begin to weave it together. I couldn’t get the strips really close together, but that was fine. As I said, above, that weaving is shown in the center of the group of three. (The frame around it was made from fresh, regular clay.)

I had a little bit left from that test, so I added a little more glycerin, kneaded it in (it was easier this time), waited maybe an hour or two, then I rolled out a couple more small bits and left those to dry overnight. Voila! The dried clay was enough-more flexible that I could weave the strips much closer together: the pendant to the right in the collection was the result of that.

(The one to the left in the trio was made later; the photo is an old image, taken to promote one of the first “woven silver” workshops I taught.)

But this getting-more-flexible trend was appealing. I had just a tiny bit left, so I added one more drop of glycerin to that. (Proportionally, with how little I had left, that was a huge amount more!) Again, I kneaded that in and wrapped it up. The next day, I found it that my final scrap was flexible enough that I could tie it into this little knot. I used the entire last bit in making this, spending time adjusting the knot to the middle so the ends would line up, meaning I didn’t have to trim any off. I used fresh wet clay to add the little coil along the top. Once that had dried (hard), I made a loop from fine silver wire and embedded that into the top. I apologize for the quality of that image: it’s a detail from a very old photo, but it’s all I have to show of that piece now.

Magic Carpet (striped frame side)Over the next few years, I continued to make my own silver clay that would remain flexible as greenware, playing with weaves, knots, twists, and other shapes in various ways. The curved-square piece to the left (which I’ve called Magic Carpet in public but is, to the mathematician that’s still quietly in me, a basic example of creating a bit of hyperbolic space…) is but one of such explorations. I learned about Hadar Jacobson and that, in her first book, The Metal Clay Handbook: Textures and Forms, she talked about this, which is one of the main reasons I bought that book … which, eventually, led me to learning much, much more from her and her approaches!

When Hadar came out with her clays, I played around with them for a bit. But I didn’t go all-in for her clays until two things happened around the same time: Hadar herself came to town (well, our local metal clay guild chapter brought her in!) to teach a workhop on her “married metals” approach (which I took), and I started playing around with adding glycerin to her original line of clays, which she now calls the “flex” powders, because they are the most (not the only, but the most) conducive to having glycerin added to yield clay that stays flexible if you want that. (If you want the clay to dry hard, just don’t add anything besides water to the powders.) Mixed Metaphors, shown to the right (before it got its bail and went to live with my cousin Debby) is one example using copper, bronze, and a little bit of steel while combining married metals with weaving.

The other thing that people do with glycerin-enhanced metal clay is to cut it with electronic cutters, like the Cameo and Portrait products from Silhouette. (That was actually one of the things I’ve been hoping to write a bit about this coming winter!) People started by cutting out the very thin PMC+ “sheet” product with that. (I don’t know this for sure, but it would not surprise me to learn that “sheet” was the inspiration for trying glycerin! Though “sheet” acts somewhat differently than does glycerin-enhanced clay, with both the point is that they never quite dry out completely, and thus remain flexible. While sheet does make nice, plain embellishments, the advantage to glycerin-enhanced clay is that you can add textures in various ways, and make it thicker or thinner as required for your design.) When folks started trying to cut sheets of regular clay with it, the question became whether it would be helpful (or not) to add glycerin. (The short answer is: sometimes, yes; sometimes, no. The full answer, available now in various online sites, will be tackled here in future posts … eventually!)

At last, on to the new PMC Flex fine silver metal clay. Needless to say, when I first heard about the new PMC Flex, I was both eager to try it it and wondering why one might purchase that rather than just go the DIY route. When I first got my hands on a pack of it, I began by trying the techniques I have in finger-memory, the ones I’ve been doing and teaching for years, just to see how it performs. The very first thing I did was to grab a little piece of it (a bit less than 1 gram), and roll it out into a “snake” or “rod” shape. I left it to dry over night.

The next morning, I measured it: 3.25 inches long, and the size of 15 gauge wire. (Clearly, it will have shrunk a bit while drying, and will shrink even more when it’s fired. But that’s it’s “dry” measurement.) It seemed like it would bend, but felt a little stiff. I’ve had that experience with the glycerin-enhanced clays too, and found that gently “working” the piece along its length will often make it more pliable: I tried that with this piece, with the same good result.

I then tried to tie it into a knot. The photo shows how far I could get it to go before feeling a lot of resistance. (The calipers shifted a bit as I was setting up the photo, so they represent a visual guide and not an exact measurement, but that’s OK for this very-preliminary report…) If I want more elaborate knot designs, I know how to get a tighter bend with my DIY-flex (as shown, for example, even in my first silver knot above, which began with a bit of clay about the same size as this). Still, this PMC Flex will clearly be great for a variety of other applications. I plan to write more about those, with photos, in future posts. As ever, as time allows…. But I’ll close by saying that it is a lot of fun to have such a delightful new toy to play with!


Update:  With Hadar Jacobson’s Flex-clay powders, one trick to slightly increasing the flexibility of a piece of “dried” clay is to refrigerate it for a little while.  I tried that with the above piece and it seemed as though it was going to let me pull it a little bit tighter.  That is, until is broke just about in half.  I’ll use the two pieces some other way, but figured I should note that (as a reminder to myself, as well as information to you…).

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Trying Hadar’s White Satin

Posted by C Scheftic on 2014/02/19

Another new clay means another trial making rings!

Though I love rings–both wearing them myself and admiring those on others, in shops, at galleries–and I love making small adornments using metal clays, in general rings are not my favorite things to make. I’ll leave the reasons for that for another post specifically about rings. Why? Because today I want to talk about rings made from another “new” clay! Now that I’m familiar with a number of different types of metal clay, one of the things I often do to try to get myself comfortable with a new one is to make myself some rings out of it–to test what it’s like to work with–and then wear them everywhere–to test how they hold up. And my first question about an iron-bronze formula in particular was whether it would hold up as well as I might expect under all the stresses I put on rings.

So one of the first things I made when I got my hands on a (pre-release!) tube of Hadar’s new White Satin was to try making a couple of rings. I wasn’t going to be able to make them my favorite way (with iron in it, I was not going to count on being able to fire the shank first and then form it around a mandrel–a method that pretty much guarantees it will come out a perfect fit–and I was too eager to try it to first make a little test strip to see if/how I could manipulate it, though if will try that eventually…). And I didn’t want to make a ring using the “common” metal clay way, shaping a band in the clay-state (with lots of potential shrinkage-issues during firing). So my first White Satin rings were a pair of seamless stackers with each one textured on one side (using the “eastern paisley” design from Cool Tools) and plain on the other side.

My plan was to make them two different shapes, and wear them with the “plain” sides together. And, no, they didn’t warp during firing: I made the openings oval on purpose!

I usually make my rings either oval (as shown here) or square-ish (a rounded-corners trapezoid). The latter is easy with metal I can whack around something like the finger-shape mandrel from Rio Grande. Since I wasn’t yet ready to try that with White Satin, I just cut the clay itself with an oval opening. Hadar said rings would shrink about 3 sizes, so I used that for my beginning estimate.

Though, since I was making my rings oval, I did cut the opening a tad smaller than that. What I really did was to fit a narrow strip of metal inside a ring sizer at the +3 size, but then trim it a tad smaller. I then shaped that into an oval, and used that to cut my clay. The reason for down-sizing a tad is that, to put on an oval ring, I turn it sideways until it’s passed over my knuckles, but then turn it back up to wear. The “twist” allows the larger-direction opening (still at the +3 size) to fit over the larger-dimension part of my finger. But when it gets twisted back again, the straighter side (now smaller and narrower) holds each ring upright better, so I don’t have to keep straightening them.

The rings shown here were fired and then polished. And they did come out fitting the finger for which I was trying to make them! Since they contain iron, which will rust, they were sprayed with an acrylic protectant. Since they are rings, I have no clue how long that protection may or may not last. That’s what I’m now trying to test! I’ve been wearing them off and on for almost two weeks (more on than off, but nowhere near constantly) before taking these snapshots. They seem to be holding up fine in the short term. It’ll just take more time to see how they do over a longer stretch.

In the meantime, I am very happy with the results so far, and I hope you appreciate this early-report.

~~~~~

Update: This post originally referred to White Satin as a form of steel. I have since decided that it is more appropriately described as a form of iron-bronze, and have edited the post to reflect that. (Bronze is an alloy of copper and tin. Different proportions yield metals of a different color. Rose bronze, for example, has more copper than does the typical yellow-bronze. White bronze has more tin. which produces a nice color when used as an accent, but results in a metal that is too “fragile” to be used as a major structural component. Hadar’s White Satin is a bronze formula that contains some iron too, which produces a black-metal that can be polished to a white-metal color but has the strength more like that of a typical bronze….)

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Update on the Lifespan of a No-Flake Foil Firing Box

Posted by C Scheftic on 2014/02/10

A few days ago, I was talking with another metal clay artist about how I fire bronze, copper,and steel in vessels I “fold” myself from sheets of steel “no-flake” foil, when I realized it had been two years since the last time I’d mentioned them here.

Which I find interesting: in three years, I’ve used three boxes! Counting them up, I figure I put a box through a firing somewhere between 1 and 2 times a week, on average. But few things in my life are average…! No, really, it’s more like 6 or 7 times a month, but even that tends to happen in maybe two “bursts” of several firings in quick succession, then it’s several weeks before I do that again.

Something I learned from my first no-flake foil box, plus discussions with others after I wrote about that, is that the foil tends to crack open along the top edge of however much carbon is typically used. So, with my second box, I started out by piling the carbon a a little bit higher than I’d been doing. Then, when some cracking started to appear, I could just lower the level a bit, and get a number of additional uses out of it (because the holes–eventually stretching into a longer tear–were then above carbon, it didn’t leak out)! With the extra firings, it also began to crack along the top-most folds: what that meant is that I tried to be a bit more careful as I handled it, especially when moving it in and out of the kiln. Eventually, though, I decided I was carrying conservation perhaps a bit too far: after at least 75 firings over the course of a year, I took its picture and retired it!

Box #3 has lasted even longer! It has handled 80-some firings over almost 14 months. I did not keep fully-detailed records but, between the notes I do have and my general memory of the past year, I’d say that for its first year, I did a higher proportion of firings in the mid-fire range, and a smaller share in the high-fire range, than I had done with the first two boxes. That seems to have reduced the number of little holes it developed, so there were fewer to spread into wide-open cracks.

That is, until the start of this calendar year. That’s when I started playing with Hadar’s One-Fire High-Fire Trio. The single firing needed to both de-binder the clay and sinter the metals is a real treat, but when I started firing batch after batch in the high range, I noticed that the sides started warping out. So, even though Box #3 does not have any big holes, it is now being retired because I can barely fit it in he kiln any more: it is in danger of hitting the kiln’s thermocouple!

But. I still think that these boxes are well-worth their cost! Do you?

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Who knew?! Colors, polishing, etc.

Posted by C Scheftic on 2013/11/12

Back in August, I wrote about one of a series of “pillow” beads I’d made using Hadar’s Quick Fire Bronze powder. In particular, I ended the post with a photo of the amazing colors the kiln provided that time, and a comment that I knew they were somewhat ephemeral.

Well, yes, after only a short time (and despite having tried to “protect” them with several layers of acryllic spray), they became rather dull. Still there, but no longer jump-out-at-you vivid. So I proceeded to do some polishing (moderately aggressively in the center-design area, and more gently around the edges) and then re-coated everything. This provided pieces with clearer bronze-yellow center-designs, while still maintaining a trace of the kiln-colors around the edges. I didn’t really think the vivid colors would last, but the subtle ones shown here have remained much more stable ever since. I’m pleased with these results.

The thing that did surprise me, however, was something that had not been at all obvious with the vivid coloring, but did jump out at me (peering closely through my bifocal safety glasses for magnification as I worked): my straight pencil-lead “registration” marks — ones that I’ve come to use often (to align parts or holes or … ) on silver clay that is fired in regular air — do not simply burn off when you bury bronze in activated carbon during firing. Who knew?! Did you? It was a surprise to me, so I thought I’d share it with y’all.

If you want to give your piece a bright, shiny polish, it’s very easy to grind (sand) the marks off. (I did that with another piece, just to be sure, though I didn’t think to grab a before-photo to use here.) But I didn’t want to do that with the pieces shown above, especially not to the one towards the right (on a brass chain). I liked its aged, colored look. So I’m just leaving the straight-line mark. I showed the piece to a number of people (metal clay artists and otherwise) and, in person, it didn’t seem to jump out to anyone (until I pointed it out to them). I’m now just calling it a part of this piece’s design.

These are now ready to go off for holiday-season sales. I hope they find good homes!

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Two More Hollow Beads

Posted by C Scheftic on 2013/08/31

While I’m still thinking of it, here are a couple other hollow beads I’ve made recently, and the armatures on which I built them.

Well, let me start with the armatures. In the first photo, you can see two oval-dome parts of a graduated, five-part “doming plate” that is sold specifically for use with metal clays. (This one actually belongs to a friend, who won it in an online contest!) Below that is a square, blue, glass “rock” that is sold in the floral-arranging section of a craft store. (That is mine, one of three I found in the back of a drawer in a house I rented for a while. I liked their sea-blue color.)

The first piece shown here, reversible with both sides in the photo to the right, was made with the glass rock. I covered it with a plain layer of bronze clay, let that dry, cut it open to remove the rock, and pasted the two parts back together again. Once that seam had dried, I then covered it with what I thought of as three different “blankets” — each with a different woven texture using a different metal (all from Hadar’s Quick Fire clay powders). The first layer was bronze which, when fired, had a lovely sort of blanket-y color that I left alone. The next layer (the wavy weave) is rose bronze, and the outermost later (a straight weave design) is copper. I did them in that order because I’ve found that copper layered over bronze, with air-filled gaps in between, sometimes alloys into odd colors. The rose bronze serves as a sort of buffer to help avoid that. (And, I just like the color of the rose bronze metal!) Both the rose bronze and copper were polished with radial bristle disks and silicone wheels to bring out their shine.

The second piece shown here, also reversible, with both sides in the image to the left, is all bronze, and was made with the second-largest shape on the doming plate, with some additions. First of all, I cut a flat oval shape just a bit larger than the dome. I let that dry, attached the dome, and dried it yet again. Then I rolled out a thin, textured layer and “draped” that over the other side of the flat oval. I used a straw to prop open a place near the top, to serve as a bail, trimmed the rest to match the oval, and let it dry one more time. After cleaning it up a bit, I fired it. I decided to polish this piece using the same tools as I had on the “blanketed rock” piece.

Although these are both relatively simple pieces, they illustrate one of the things I find so very engaging about working with metal clay: the wide range of creativity it brings out, not just in the designs one ends up making, but also in the range of items one can either find or adapt to use as “tools” to aid in the making. Maybe I can remember to show more of those over the next few weeks. In the meantime, feel free to leave a comment describing other such items in your “tool” stash!

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Hollow Bead Armatures

Posted by C Scheftic on 2013/08/21

I like making hollow beads. I sometimes wonder how much of my fascination with them is because the first piece I ever made using metal clay was a hollow bead, shown to the right, and how much is simply because they can be both fun and interesting to make. I’ll never know the answer to that, but I expect to continue enjoying making them.

In the class where I made that bead, I dried the pieces for each side over a light bulb. The nice thing about light bulbs is that, if you prop them up with the screw-end down, their tops really are nice and round. Why does that matter? Because it means you don’t have to worry about centering, or otherwise specifically positioning, your clay on it to dry. You just move it onto the bulb, carefully press it down to match that curvature, wait for it to dry, and admire the nicely symmetric results.

There are a few minor complications with using a light bulb. Nothing serious, but things to consider. How will you prop the bulb? In that first class, the teacher had two kinds of holders: one was a small paper cup turned upside down with a slot cut into the base and the other were small blobs of polymer clay into which she’d pressed the end of a bulb to form it before curing that clay. (Of those two, I have a small preference for the paper cup approach (as shown here, to the left) simply because, when I’m storing enough of those to use for a class, I can stack the cups so they take up very little space.) Another consideration is that you are then working with (i.e., moving around) a piece of oiled (i.e., slippery) glass, where slippery means easy to drop and break. Can’t you just hear the “voice of experience” there?!

So, what else to use for an armature? A few of the things that I’ve tried (some of which are shown, to the right) include the following:

  • plastic eggs (bottom), but you have to take care to use the “round” end because, with the “more-pointy” end, then you do need to take a lot more care with how you position your clay on it to dry;
  • measuring spoons (top) but, again, you need to take care to get round ones;
  • ping-pong balls (middle row), which I like to cut open so they don’t roll around, and
  • plastic paint palettes (not shown) which, like the other items shown in this colorful collection, are also “open” on the other side, so you can turn them over and position your clay on the inside too, should you want to do so.

Which armature is best? I don’t have any one favorite. So, how to choose which one to use? Me, I think about the size of the piece I want to make, and the amount of curvature I want it to have, and pick whatever happens to match that the best. And sometimes, yes, I do return to the old light-bulb trick, as I did with a piece I made recently out of Hadar’s Quick Fire Bronze clay. This piece was not going to be round (like my first-ever piece); I wanted this one to have more of a “trapezoidal” shape (i.e., a rectangle with only two parallel sides). This piece would be fairly large but, because of its non-round shape (meaning it would end up having four “side” or “edge” areas that I would then have to fill), I did not want it to have a lot of curvature. Instead of a “standard” incandescent bulb (as used with that first-ever piece), this time I used a larger round “vanity” bulb. With those, instead of turning a cup upside-down to hold the bulb, I’ve found that they fit nicely inside a large cup. So that’s how I positioned my two “trapezoid” pieces for drying. Since this was the last piece I started one day, I just positioned them over the bulb, made sure all the edges were tucked down smoothly, and left them to dry over night. As I was packing up my camera, for no obvious reason I decided to snap a quick photo of them before I left.

The next morning, I was surprised (which, in fact, surprised me even more: I was surprised at my surprise….) to find that, once dry, they had released themselves from the bulb, and slid down to the side, where they were caught by the cup holding the bulb! Whew! I would have been very disappointed if the dry pieces had fallen from a noticeable height onto the tabletop and, perhaps, even then bounced down to the floor (as could have happened if I’d stuck them into an overturned cup) and, quite possibly in their “dry clay” state, cracked or even broken apart from the fall. (Yes, I know how to patch them should that happen, but it takes time and effort that I’d rather just avoid. And pointing that out to you, dear readers, is the whole reason I decided to write this particular post!)

Since I mentioned the “edges” this piece would have, this next photo (left) shows the opening along the “top” of the piece after I’d attached the two main elements. (I hesitate to call them the front and the back because, like most of my work, this piece is fully reversible: it has two different fronts!) I’ve got it standing on quadrille paper (with 1/4 inch squares) to help give you a sense of its size. Once I had covered each of the four edges (the openings that I’d wanted to keep to a relatively small size by using an armature with a relatively shallow curvature), I inserted a bronze “embeddable” bail in the top and fired the piece.

And I was delighted with the result. My original plan had been to finish this piece to a high shine but, given the colors the kiln decided to give it that day, for now at least I’m leaving it like this. Yes, I know, the colors are somewhat ephemeral. I’m experimenting with a new acrylic coating to see if / how it may help to preserve such colors. So this piece won’t officially be going up for sale right away, until I can see how it holds up. You may, instead, see me wearing it as part of the testing process. (Which I find to be another part of the “fun” of making pieces like this.) But, what do you think: if the colors do hold up, should I leave it like this, or remove the coating and polish it until it shines?

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Smart Bronze: By Jove, I Think I’ve Got It! (Summary — Post 6 of 6)

Posted by C Scheftic on 2013/06/30

Before I wrap up my Smart Bronze test-reporting, I am inclined to take one last post to review and summarize a few of my thoughts about what I just put myself through.

My Test Firings.

Over the last five posts, I outlined the eight firings I called “trials” to master the firing of this particular clay. If I were starting the whole thing today, I think I could hit the right numbers in a mere three trials. Yes, that’s more than one test-firing, but I do find that to be a very manageable number. (Yes, eight was too many!) Why do I say three?

My first two firings were based on Hadar’s earliest information, right as this new product was released, before she had updated her Instruction Manual. Today, I would be starting with the later information, and avoid a couple of initial mis-steps with this new product.

My last two firings were, really, my first two production firings. I counted them as tests mostly because, having encountered some earlier problems, I was being particularly cautious before declaring my testing done.

Finally, the problems I had in one firing in the middle were simply because I’d spaced out and incorrectly programmed my kiln. Those did give me some more “confirmation” of what I thought had been going on but that should have been avoidable.

That leaves me with the three firings I think I would have taken to get it right. And you should be able to hit it right in two or three yourself, because you will know the following….

The “Trick” to Smart Bronze.

The conversion of all metal clays from a powder-form into a metal-structure one (oh, and regardless of whether they are precious metal (silver, gold) or non-precious (elemental copper or various bronze or steel alloy formulations)) requires that both (a) all the binder be burned off and, then, (b) the metal sinter and “soak” into a nice, densely-packed arrangement. In some cases, those can be done in one (sequential) process; in others, it requires two (separate) firing processes. “Smart Bronze” falls into the former category, which is its primary appeal over a number of other bronze formulations.

But you really do have to let Smart Bronze pieces spend a full hour in the “debindering” process. In a single-fire product, all the binder burnout happens during the ramp-phase of a firing. If it’s not taking your kiln an hour to do that ramping, you are probably not removing all the binder, and that will limit the metal’s ability to fully sinter correctly regardless of the temperature or time at which you “hold” it. You have two options for slowing it down: reduce the ramp-speed, or simply build a few minutes of “hold” time partway through the heating-up phase of a firing. (I did the former, as noted in this series of posts, with my brick kiln. I am thinking I may well try the latter when I get around to trying to fire this clay in my ceramic muffle kiln.)

Once you are sure you’ve adequately provided for the binder-burnout phase, only then can you confirm the actual goal-temperature that’s needed to allow sintering to take place. I know that our instinct, when sintering does not seen to happen as we’ve expected, is to try to adjust the final temperature or hold time with the expectations that such tweaking will solve the problem. But, until you get all that binder burned out, your metal will not sinter properly. You have to master the burnout-phase first. Every situation I have heard about where there has been a problem with Smart Bronze (at least so far) has involved inadequate sintering that, at least as far as I could tell, resulted from a problem in the initial heating up part of the process, when the binder should all be burning off.

A Note on the Color of Sintered and Polished Smart Bronze.

The two rings pictured with this post both contain large areas that have been polished smooth. The round, seamless ring has been completely polished. So has the band of the double-fire ring, as well as large, raised areas of its texture. In such cases, the metal polishes up to a bright, golden-yellow color.

On textures with lots of fine detail, however, such as the earring pairs in my last post, where you can’t really polish everything to a super-high shine, then the color looks to me to be more of a greenish-bronze. (During the testing, I tried both: (a) using sanding plus further polishing, and (b) tumbling in a rotary tumbler. And I got a similar greenish tone either way.)

I’m not saying that either one of the colors — golden yellow or greenish bronze — looks better than the other. Just that they are rather different, and seem to be a result of the texture rather than any other construction, firing, or polishing approach that I’ve yet been able to determine. I have definitely begun planning pieces with one shade or the other in mind (e.g., with respect to some particular stone-color I may choose to add to a piece). I’d love to hear whether (or not!) you find a similar pattern in the pieces you make out of Smart Bronze.

Because, my readers, I sure am hoping you’ll try Smart Bronze too. Once you “get it,” it’s great. I’d love to hear how your results compare to mine!

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Smart Bronze: By Jove, I Think I’ve Got It! (Post 5 of 6)

Posted by C Scheftic on 2013/06/30

This post continues the story I’ve been telling about coming to understand Smart Bronze metal clay….

By now I was feeling time-pressure on top of some test-process frustration. What pressure? The various “test” pieces in Smart Bronze had not taken that much time to make, in and of themselves. But their firings had been eating up kiln-time. I was making and firing pieces in other metals in between so that I’d have enough inventory for the Three Rivers Arts Festival (held June 7 through 16 this year). Aside from the rings, which I’d been doing just for myself, I’d been thinking the “test” pieces might serve as the “loss leaders” in my collection at the Festival: an option for someone who really wanted something of mine but could not afford the higher-end pieces. (I’d make sure to cover my actual costs with them, but would take some loss on my time by just calling that testing-learning overhead.) And I write about all of this, now, as a teacher: to illustrate that even someone who, in general, does know what she’s doing … can also hit roadblocks, make mistakes, continue exploring, and figure things out. Just in time!

Here’s what happened next:

Trial #7: Early June in a Brick Kiln

Hadar (still) said: Ramp at 1400 per hour to 1430°F and hold for 2 hours.
What I entered (correctly, this time!): Ramp at 1350 to 1395 and hold for 2 hours.
Program completed in 2:59.

Test pieces: Taking a risk, I fired all of these: another open-ended ring shank, several botanic pendants and a collection of earring elements. All came out looking fine! Whew!

Trial #8: Early June in a Brick Kiln.
Or, have I moved beyond Trial Firings to Real Firings?!

Hadar said: Ramp at 1400 per hour to 1430°F and hold for 2 hours.
I entered: Ramp at 1350 to 1395 and hold for 2 hours.
Program completed in 2:59.

Test pieces: Once I’d attached a new “top design” to the ring shank from trial #7, I fired that in the kiln, along with another collection of little earring components. (Shown, here, are ten pieces I included in this particular load.) Once again, all came out looking fine. I could actually wear the ring! In the time since these last two “test” firings and my getting around to writing this report, I’ve sold almost all the earrings and pendants I stuffed into these test-loads. Success, at last!

And the ring, which I wore constantly during the Three Rivers Arts Festival and have continued to wear frequently since, is holding up beautifully:


I’ll close this series with one final post, summing up what I’ve learned in the process.

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Smart Bronze: By Jove, I Think I’ve Got It! (Post 4 of 6)

Posted by C Scheftic on 2013/06/29

This post continues the story I’ve been trying to tell for the past two days….

Trial #6: End of May in a Brick Kiln, in which you will see how your tester spaced out momentarily….

Why had that last load’s wrap-ring broken: was there a weak spot, or was the firing program still not right? I didn’t want to risk breaking the seamless ring too, but I thought maybe I’d try firing it a second time just to be safe. I’d also made an open-ended ring “shank” for a double-fire ring that I could put into this load, as well as a couple other simple textured butterfly pendants I’d made up while the last load had been firing. And I’d nudge the hold-temperature up just a tiny bit while I was at it.

Hadar (still) said: Ramp at 1400 per hour to 1430°F and hold for 2 hours.
What I thought I entered (which I’ll explain in a moment):
Ramp at 1350 to 1395 and hold for 2 hours.
Program completed in 2:59.

Test pieces: Now, I had blistering. Just two little blisters on the open-ended shank (shown: first, right). The textured pendants were bubbly all over. So was the seamless band (shown: second, left): it had had a “perfect” finish on it but, since I’d broken the other ring I’d fired with it, I’d stuck it in to see if a second firing would better-sinter it and now it looked a mess. Fixable, I hoped, but still … why?!

My first reaction was, yes, the load had been slightly larger than the previous one, but why so much blistering? Having felt a little bit frustrated at the start of this trial, now that feeling was building up even more. I’d worked on a few pieces in other metals between trials #5 and #6, and succeeded in gaining a bit of positive reinforcement for myself from their success. So I returned to more of those after trial #6. And. as I went to put those in the kiln, and set up the program to fire those, that’s when I noticed that I’d somehow spaced-out entering the program for trial #6, and gotten wrong both the goal temperature (slipping back to the previous trial’s number) and the ramp (where I’d entered the (wrong) goal number, not the ramp number). And, somehow, the firing time came out to be the same as other test loads, so that was no clue either. Argh…. ( I had actually been starting to wonder if, somehow, the load-timer was malfunctioning and always just returning the last reliable number it had ever had….) But, now, here’s what I’d done:

What I meant to enter: Ramp at 1350 to 1395 and hold for 2 hours.
What it seems I entered: Ramp at 1400 to 1400 and hold for 2 hours.

Little differences can mean a lot! What can I learn from my observations, both before and after I realized my mistake? The textured pieces had bubbles that clearly did not belong to their textures. Ugly! But, though the rings both, at first, looked fix-able, I was even more disappointed by them! The seamless band had blistered, but I was able to work away at it (for a very long time!) with various sanding attachments on my rotary tool until I got it back to a nice condition. Not as pristine as it had been after its earlier polishing, but still very nice. And, it had shrunk another whole size (meaning it had gone down by a total of three ring sizes), which told me that the refiring had resulted in more sintering. At least that was a good sign. But the open-ended band, on the other hand, did not seen to have shrunk much, if at all; worse yet, it broke into three pieces when I slipped it (carefully!) onto my ring mandrel to check its size. Even though it looked at least reasonably well debindered, was it possible that the faster ramp had prevented all the binder from burning out? Or … what?! Of course, I’d made a mistake. It was just “little differences” here and all I needed to do was to go back to the pattern I’d been developing and it should work. I kept telling myself that.

So, let’s take a little break here, to clear our heads….

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Smart Bronze: By Jove, I Think I’ve Got It! (Post 3 of 6)

Posted by C Scheftic on 2013/06/29

This post continues the story I started telling yesterday, morning and evening….

By the time I got around to trying Smart Bronze again, a newer version of Hadar’s manual was out. Dated May 15, 2013, it told me that my goal in the first trial, 1420°F, was really only 10° below the (latest) recommendation, of 1430°F, whereas I’d intended to aim for 20° below Hadar’s recommended temperature. My second trial had still gone a bit too fast, yes, but it turns out that one really had been at my typical Hadar-clay adjustment of 20° less than the stated goal. That explained all the melting and left me a bit less worried, now, about whether I could get away with dropping my goal temperature some more as I also slowed the ramp speed.

Trial #3: Just after Mid-May in a Brick Kiln

Hadar (by then) said: Ramp at 1400 per hour to 1430°F and hold for 2 hours; total firing should take 3 hours.
I entered: Ramp at 1365 to 1400 and hold for 2 hours. This should have taken over 3 hours; the program completed in 2:58.

Rationale for my new program: (1) Further slowing the ramp should continue to improve the binder burnoff. (2) This was still only 30° below Hadar’s newer target (hold) temperature.

Test pieces: the last (and smallest) two “golden threads” loops that I’d made along with the ones “lost” in the first two trials.

Results (shown, held up inside a slit in some green foam): Both test pieces seemed, at first, as though they might be debindered and sintered. But one small segment did break under very slight pressure (i.e., yes, the “threads” were thin, but this felt like a “normal wear” issue; I had not deliberately test-bent them but, instead, just lightly squeezed a wire-like bit with my fingers to get a good grip on it for polishing). It was hard to see the inside of the small ends. They seemed sintered, but perhaps not fully so. Still, this felt increasingly close to a program that should work.

What to try next: Since there had been so much melting in the previous trial, at 1410, I was hesitant to blame any inadequate sintering on too low a firing (hold) temperature. Since any not-burned-off binder will inhibit sintering, I decided to maintain the temperature and try dropping the ramp-speed a bit more….

Trial #4: End of the third week of May, in Brick Kiln

Hadar said: Ramp at 1400 per hour to 1430°F and hold for 2 hours.
I entered: Ramp at 1350 to 1400 and hold for 2 hours.
Program completed in 2:59.

Test pieces: I wasn’t sure if the thinness of the “threads” might have been a factor in the previous failure. So for this trial I reverted to a simple design I know and understand well: two small, round, simple, stamped butterfly pieces. (One each at 3 and 4 cards thick.)

Results: Debindering seemed to have happened as needed. The pieces sintered into a nice, solid metal. A few small blisters appeared, but they were fairly easy to polish down. The results looked lovely but I have no pictures: sorry! The reason for that is great: As I was finishing their polishing and stringing them up to photograph, a delightful fellow walked into my studio looking for a gift for his twin daughters and bought them both!

Trial #5: Brick Kiln

Hadar (by then) said: Ramp at 1400 per hour to 1430°F and hold for 2 hours.
I entered: Ramp at 1350 to 1390 and hold for 2 hours.
Program completed in 2:59.

Test pieces: I was ready to go for it! I’d had several ring bands ready for weeks! One was made using the “seamless” ring approach; the other was made as a bypass or wrap-ring although I did “connect” the edges of the two ends as they passed each other. I did the latter because I wanted to help keep the piece a bit more stable than it would have been had I left it with “loose” ends.

Results: Both seemed to debinder and sinter beautifully. My only concern was that they had not shrunk by the predicted 2.5 sizes. I was seeing them as not quite 2 sizes smaller. Was that enough? Had I dropped the temperature a little too much? Maybe. Maybe not. But I was hopeful. I first polished the wrap-ring, which looked gorgeous, so I wore that happily while I worked on the seamless ring. When I left my studio at the end of the day, the seamless ring was sitting there waiting to be photographed with its kiln-mate. (It’s shown, here, alone.) I wore the wrap-ring home. The next two days had me moving some furniture and packing-boxes from a recent home improvement project, along with other normal daily activities. I continued to wear the wrap-ring and, half-way through the second day, it suddenly broke into three pieces.

Admittedly, the wrap-ring design did have one “thin” spot. The band was an even thickness all around (which you can see from its greenware-state photo (brown color) above), but it been cut in a tapered shape, so it had the least “height” right where it met the large starting-edge. Which could have been a point of weakness. Which could have explained its breaking open. Or, maybe even breaking into two pieces. But its breaking into three pieces hinted to me that there was another problem somewhere. Less obvious, of course, was the exact nature of that problem.

Should I worry about the pendants I’d just sold? I think not. They were thinner, and less likely than a ring to get knocked around a lot. Still, there was another pause in my testing so I could think this through some more: and another point at which I’ll pause this record too.

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Smart Bronze: By Jove, I Think I’ve Got It! (Post 2 of 6)

Posted by C Scheftic on 2013/06/28

This post continues the story I started this morning, reporting activities from last month….

Trial #1: Early May in Brick Kiln

Hadar (back at that time) said: Ramp at 1400 to goal-temp of 1440 and hold for 2 hours.
I entered: Ramp at 1400 to goal-temp of 1420 and hold for 2 hours.
This should have taken just over 3 hours; the program completed in 2:42.

Test pieces: one small stamped disk and one “golden threads” loop (the latter was a simple project from Hadar’s blog when she introduced the product she calls Brilliant Bronze).

Results: Two test pieces were simultaneously under- and over-fired! That is they were under-fired in relation to the debindering phase, and over-fired in relation to the sintering phase.

How did I know this? What I found were small, uneven blobs of bronze (i.e., over-fired at the end) that, when handled and examined, disintegrated into small bits of metal and dust (i.e., under-fired at first). The firing finished late at night and I was tired and a bit frustrated: I tossed them before thinking to try to take a photograph.

What to try next: Even though this material can be fired in just one round, the conditions still have to be right for both (1) debindering and (2) sintering to happen as desired during the (1) ramp and (2) hold phases, respectively. Clearly, this kiln-program was not the right one on either count. I’d have to adjust it in several ways.

Trial #2: Early May in Brick Kiln

Hadar (still, back then, though later revised) said: Ramp at 1400 to 1440 and hold for 2 hours.
I entered: Ramp at 1375 to 1410 and hold for 2 hours.
This should have taken over 3 hours; the program completed in 2:45.

Rationale for my new program: (1) I was hoping the slower ramp would allow for better binder burnoff. (2) Since Hadar’s other clays all worked great for me at 20° less than her posted temperature, I wasn’t yet ready to go plunging further than 30° below her number.

Test pieces: two more “golden threads” loops that I’d made along with the first-trial one. (Thinking I’d done with testing after one try, I’d added small ball embellishments to these.)

Results (shown): Both test pieces seemed, at first, to be a bit better debindered and sintered than the previous trial. They did show some signs of melting, but nothing like the last time. Still, they broke under very light pressure while holding them to photograph them. It was hard to see the inside of the small ends. They might have been somewhat sintered, but certainly not fully so. Still, this felt like some (if small) progress from the first mess.

At that point, I took some time off from this testing, and will pause my report here. Before I close this post, however, I’ll add one other thought.

A Comment on the Name: Smart Bronze.

As a customer, who is buying this product to use myself, the name almost makes some sense. First of all, unlike many other base-metal clay products (from Hadar and others), it should be possible to process this one in a single (reduced oxygen) firing. Many of the others require two firings of one sort or another, but this product was developed to be “smart” enough to both debinder and sinter all in one go. Which is very convenient! Also, it does polish up to a lovely color, a color that one might call “very smart”…. (And, for anyone familiar with Hadar’s Clays, a curious pun in comparison to her Brilliant Bronze.) But, as a maker, I do find it an awkward name. It’s not one I would want to use on the label of a piece I made using it. More on this in a later post (most likely after I’ve finished this whole series on testing).

Because that’s it for right now. But I’ll be back as soon as I can with more info.

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Smart Bronze: By Jove, I Think I’ve Got It! (Post 1 of 6)

Posted by C Scheftic on 2013/06/28

The newest Hadar’s Metal Clay Powder product is called Smart Bronze. I spent over a month playing around with it, and I think I finally figured out some things about it. (Not everything, mind you, but at last I feel well on my way!) After then spending a few weeks catching up on a several other urgent tasks, I’m hoping I can finally find time to post here a collection of thoughts and experiences.

A Bit of Context.

OK, it’s not like a spent a solid month and more figuring this out. The time I spent did cover most of May, slipping into early June, but it was in dribs and drabs. To begin with, I am not a full-time jewelry artist! I do learn, explore, make, sell, write, and teach about it. Some weeks, it does end up being just about all I do. But there are other stretches when I don’t touch the stuff at all. Most of the time it’s somewhere in between those extremes. Averaging out over a whole year, I figure that I do this about quarter-time, or maybe a third (depending on how you count both “this” stuff and “full” time…), but only that. Whatever the actual proportion, it’s a delightful fraction, I must say! But more than that would feel like work and, though I am trying to treat it all in a very professional way, I also really want to keep this for fun. My point is that the fun I had figuring out Smart Bronze was a very part-time part of that part-time activity: though I’ll drag the description out for several posts, in reality it all went rather quickly.

Also, I have two kilns, in two different styles: one firebrick, and one ceramic muffle. So far, I’ve done all my Smart Bronze testing in the firebrick kiln. When I find some more drib-drab time, I’ll try it out in the muffle kiln too. But if you are reading this in the hope of learning from my experience before firing the stuff yourself, it may help you to know that both my kilns have inside dimensions of about 8 by 8 by 6 inches. The firebrick one can reach 2350°F; the muffle, 2000°F. Smart Bronze fires well below both those limits.

To fire base metal powder clay in my firebrick kiln, I most often use a box I’ve folded myself out of stainless steel tool wrap (e.g., the No Flake Foil sold by CoolTools), and the carbon that Hadar Jacobson recommends in her Instruction Manual (coconut shell-based, acid-washed, size 12×40). With that particular combination of kiln + box + carbon, for the majority of Hadar’s clays, through testing I have found that the ramp-speed she suggests works fine, but I should lower the goal-temperature by about 20°F from what she recommends to get full sintering without blistering or other signs of over-firing. (It could just be a difference in our kilns, but another factor could be that my lightweight foil boxes transmit the heat a little better than the heavier stainless steel bowls I think she uses?) I might do a little more adjusting for smaller containers or much fuller loads, but for what I was firing in these trials, I started out thinking that a drop of 20° should be the only adjustment I’d need.

Finally, whenever I first try any new clay, I always do at least one “test” firing first. I know that some artists plunge right in to make a new masterpiece and just fire it, but I can’t bring myself to risk something like that until I feel really certain I’ve mastered enough of the relevant firing details. At the other extreme, some people will just roll out a plain slab of clay about the same size and thickness as their intended masterpiece, and test-fire that. While much safer, I can’t quite bring myself to simply “waste” a good chunk of metal (even if it’s not a precious metal) that way, not to mention the firing -time and –energy. I have found, instead, a middle ground that works for me: I make several very simple pieces. If they fail, I’ve lost a few more minutes of my time than I would have if I’d just fired a plain slab. But I want to believe that the firing will work and, when it does, then I will have a simple little piece that I can sell inexpensively or give as a small token-style gift (instead of just a piece of “waste” material).

Working with Smart Bronze.

I found the working properties of this product to be comparable to other Hadar’s Metal Clay powders. That is, it is easy to mix into a clay form. It’s easy to work with. It has a very nice feel to it. None of Hadar’s clays are sticky, like some metal clays tend to be. (Yes, you do want to use a bit of olive oil between them and any textures, stamps or cutters you press into moist clay, but it’s not like you have to work in a complete cloud of release agents to keep it from sticking to everything!) Smart Bronze has a very good working time, and it’s easy to rehydrate if you work more slowly. It dries to a very hard state, which makes it easy to clean up and polish pre-fire (which is a feature I really appreciate).

Firing Smart Bronze.

Ah, but now, this is where the real testing comes in.

The latest version of Hadar’s Instruction Manual is always available as a .pdf file for free download from her blog. (It’s available from some other sites too, but Hadar’s blog reliably has the most up-to-date edition.) I first tried firing Smart Bronze when the then-latest version of the manual was from April 30, 2013, and it gave this information for firing that new “Smart Bronze” alloy:

Brick kiln: Ramp at 1400°F/778°C per hour to 1440°F/782°C. Hold 2 hours.
Muffle kiln: Ramp at 1400°/778°C per hour to 1495°F/810°C. Hold 2 hours.

By the time I’d completed my first few test loads, there was a newer version, dated May 15, 2013, and it had been updated to read:

Brick kiln: Ramp at 1400°F/778°C per hour to 1430°F/776°C. Hold 2 hours.
Muffle kiln: Ramp at 1400°F/778°C per hour to 1470°F/799°C. Hold 2 hours.
Pieces thicker then 10 cards or mixed with other metals should be pre-fired.

Notice that, while the ramp (speed) remains the same, there are some significant differences in the goal-temperature from one to the next: a ten-degree drop for brick kilns, and a whole twenty-five degree drop for muffle kilns! So the tests I am about to describe involve changes in temperature that are due to both new temperatures recommendations from Hadar and observation of my own results. (And readers of this blog should be able to skip the first few “issues” I encountered by just checking for the very latest version of the Instruction Manual at Hadar’s website! It’s possible there will be yet more modifications as Hadar travels and gets to see for herself how this product works in many other kilns.)

But this post seems long enough for now. I’ll be back soon with what I found out once I really got going! (Yes, in addition to my earlier comments that my testing spanned more than a month, that’s another really big hint that it took me “several” test firings to work this out!)

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Pre-firing Hadar’s Clays

Posted by C Scheftic on 2013/04/14

A Bit of Background (skip to next section if you already know the science behind metal clay firing):

Stainless Steel Bowl with
base metal greenware
(yellow bronze and
burnished brilliant bronze).

The firing of fine silver metal clays is easy! Design, construction, and finishing are each more complex than the firing itself. Yes, firing does involve some details but, once you’ve sorted out placement, position, temperature, and time, you may just turn on the kiln and go do something else while the binder burns out, the metal particles sinter, and the load finishes.

Metal clay artists working with other metals, however, know that the firing process for those is much more complex. The difference is that precious metals don’t react with oxygen when they’re heated, but non-precious metals do react. This may cause undesirable color changes (such as firescale from the copper in sterling silver). Even worse, though, these reactions can change and damage the actual structure of the solid metal even if you’re working it at temperatures lower than where they’d melt. (This is not specific to metal clay: you can destroy other metal forms the same way.) Could you just restrict the amount of oxygen during the sintering process? Not exactly! Because the “clay” in metal clay involves binders, you first have to burn off all the binder before the metal particles can sinter. And, to burn off the binder, you need oxygen. In short: at first, you do need oxygen and then, later on, you don’t want to have it.

So each “base metal” clay product provides its own instructions for firing. These offer their approach for how to (a) allow enough oxygen to burn off the binder, while (b) still allowing the metal to sinter successfully. If you understand that as the goal, and like to play around, you can try various ways to make it happen regardless of what any particular manufacturer recommends.

(A couple of years ago I wrote a series of ten posts about my experiences firing Art Clay Copper according to their instructions. In the end, I decided that I was going to abandon Art Clay’s all-open-air approach, and stick to one of the strategies that restrict oxygen during sintering even for that product.)

Now, to the Point of this Post:

For many years, in the instruction manual provided on her blog, Hadar Jacobson recommended a two-phase firing schedule for her clays (which also required a cooling phase in between). It took a long time to complete a full firing cycle (basically an entire work day), but it worked. The length of the firing process did somewhat limit the number of production runs a metal clay artist could complete, depending on how many kilns you had available, but it was even more limiting in relation to most class and workshop settings.

At some point in the last year or so, Hadar started talking about a different approach. This one used something she called pre-firing (a relatively short (half-hour-ish) firing on top of carbon to burn off the binder) followed by one full-scale firing (where you then cover the pieces with carbon and fire for a couple hours to sinter the metal). Best of all, there was no need to wait between the two! Once pre-firing was done, you could proceed straight to the final firing. That pretty much cuts in half the time required to fire a complete load.

Hadar offered two suggestions for doing this pre-firing. In each, you place the pieces on top of a layer of carbon inside an appropriate firing vessel. Then you burn off their binder either:

  • on the top of a gas stove burner, or
  • inside a kiln.
No Flake Foil Box with
six pieces of
base metal greenware &
one repair to re-fire.

Regardless of which device you chose to use, you would then cover the pieces with carbon and follow up with a firing that was pretty much the same as her old phase-2 process.

I tried it both ways and, suddenly, I began having all sorts of problems. Yes, they were ones I had seen before, but then only rarely, and they had provided enough clues for me to quickly diagnose any problems and fix them. Now, however, I was not finding ways to fix things. And, hey, the old method might have been long, but it worked for me. So I kept on using it.

But with the latest version of her Instruction Manual, Hadar has stopped even mentioning the old way. And pretty much everyone in the group of teachers going for accreditation in her program seemed to have shifted over. So, sigh, I’ve spent the last few weeks simply trying to figure out open-air pre-firing for myself.

I have not yet mastered the in-kiln method, but it seems I’m not the only one having some trouble with that one. The problem there is that, sometimes, part of the binder on the “down” side of pieces does not burn out, so the metal then cannot sinter. This may stem from the fact that, with no heat coming up from the bottom, the carbon is insulating that area too well. Heat will reach that side of each piece, eventually, once the carbon itself gets hot enough, but that may risk leaving top-sides exposed to oxygen for too long. Another approach, trying to solve that by turning the pieces over during the pre-firing, means handling very hot pieces in their most fragile state, de-bindered but un-sintered. No, thank you! Some people seem satisfied to solve this dilemma by simply firing their pieces twice, once with each side up; but if it takes that much to get them to sinter I figure I might as well just stick with the older method.

Stainless Steel Bowl with
de-bindered base metals.
(Re-fired piece is the one not black.)

But I think I am finally getting the hang of the stove-top method!!! The problems I’d been having were that my pieces were curling and/or cracking, which I knew meant they were getting too hot too fast. Hadar kept talking about turning the heat down if you saw the pieces on fire, but I never saw any flames. She talked about turning the heat down once you saw binder-smoke starting to appear, and I was taking a lot of care to do that immediately. She and the other instructors talked about how long their pre-firings took, and mine were well within those limits. After multiple attempts, I finally figured out that I really did have to heat the pieces on a very, very low flame. Maybe it’s just my stove, but I’m down to a mere fraction of the flame I’d use simply to boil water. Curiously, doing it this way does not seem to take much longer over-all than what I’d been doing before: it takes a bit longer before I see any binder burning off, but the pieces blacken completely rather quickly.

Another problem I’d had was that sometimes one or even a few pieces would not seem to burn off their binder. But I’m getting better at moving the container around over the flame, when that does happens, which seems to solve that.

I am still having the occasional failure (i.e., a bit more often than the old way), but I’m clearly making progress here. All seven butterflies in my last mid-fire load, for example, turned out fine.

Seven Butterflies
with two polished
to confirm sintering.

But, there’s something else to consider. In addition to the time that is “lost” to the occasional failure, one also has to actively watch the entire pre-firing process. You can’t do anything else useful. Well, maybe you can; but I sure can’t. It happens too quickly to catch a brief nap (yeah, I’ve been known on occasion to sleep through an entire silver-load); and it takes too much attention to spend time doing fine-finishing on pieces from the last load (which is what I usually try to do during firings). With silver pieces, I never really counted any “firing” time into their cost because I could accomplish other things while that was happening; with these pieces, however, now I do have to factor that into the price I charge for them. (I’d have that same dilemma with the in-kiln pre-fire method.) So I’m still trying to figure out how I feel about all this, but at least I have that feeling of accomplishment over approaching mastery of what currently seems to be the most popular method for pre-firing Hadar’s clays.

Seven Butterflies with
preliminary polishing complete.

By the way, even though I really am kind of swamped with to-dos, I finally figured out a way to add captions to photos that would work with this blog! It was easy, once I spent a bit of time on the task. I mention it, however, because there are some other metal clay hints buried in those notes; I’m really hoping to find time to write more about other aspects of firing in the coming weeks….

Oh, and all the pollinator-pieces used as illustrations here will be available at the Western PA Garden Marketplace on April 20. It’s not an art-event: the emphasis is on gardens and landscaping. My being there is just a little “bonus” treat, on top of all the plants and garden supplies. But if you’re reading this from the western PA area, it’d be great if you were to stop by and say “Hello!” on Saturday.

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Yep, I’m still a bit baffled….

Posted by C Scheftic on 2012/09/10

This will just be a relatively quick little follow up on my recent load of “crispy” bronze and copper pieces.

The two draped pieces actually polished up nicely. Somehow that even helped with the clunky sound they were making, that had made me even more dubious about their quality. The more-irregular one, of course, is still riddled with cracks and tiny holes: it will just look prettier in my “do as I say, not as I do” box of “teaching moments.” But none of the polishing added to the disintegration of that piece, nor did it reveal any holes in the rounder one. OK, so far.

I have not yet tried to polish the tulip with a copper flower on a bronze background because I know that one will take a good bit of work. The other two tulips turned out OK, but not as nice as I’d’ve liked. The bronze (flower) on the one to the left had actually bubbled a tiny bit and, although that did look OK after some grinding, sanding, and polishing, once I exposed it to the patina solution, small spots appeared where the edge of the blisters had been. I’m thinking that the tin in the bronze must have somehow “disappeared” at those points, leaving more copper to react with the patina chemicals. And, despite a lot of grinding on the other one, I did not seem to have eliminated all signs of the earlier cracking.

I have enough else to do right now anyway, I may just put those into the “seconds” bin that’s always seemed popular among my teenage visitors. Less than ideal, but perhaps not a total loss.

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Well, gosh, was that ever exciting…!

Posted by C Scheftic on 2012/09/09

For a number of reasons not worth going into here, I’ve been a bit distracted lately. No crises, just too many things that need my attention all at once. (Yes, like most 21st Century American women, there are always a lot of demands on my time. But sometimes the number just sneaks up over the top of what is manageable.) And then, there are the days when you think you really are accomplishing something, at last, only to find out that was not the case. This post is a tale of both of those at once.

But, since this is a metal clay blog, let me begin by reviewing the process for firing items made from Hadar’s clay powders. The first photo with this post shows three pieces that had been fired earlier, had cracked a bit in that process, were then patched, and had just been refired in the session to be discussed here. That kind of cracking happens sometimes when mixing copper and bronze, as in these pieces, and the patching and refiring—often multiple times—is just part of the game if you want those mixed-metal (sometimes referred to as “married metal”) looks. (I’ll talk more about that more some other time….)

For full details on the firing process, of course, you should always check Hadar’s blog itself. But, in general, there’s a multi part process:

0. You mix the clay, form the piece, let it dry, and then…
1. You burn off the binder, taking as long as you need according to the size of the piece(s) as well as the method you are using (for jewelry-size pieces, this can often range from a quick 1/4 hour to 2 full hours; larger pieces can take even longer) and, finally
2. You “sinter” the remaining powdered metal into a more solid form during a two-hour firing process.

This discussion addresses only steps 1 and 2. (I started counting at 0 because the final two steps are often referred to as Phase 1 and Phase 2 firings.)

When Hadar first introduced her clays, the basic process went like this:

A1. Fire the pieces buried in carbon, uncovered, in the kiln. Let everything cool back to room temperature.
A2. Top up the carbon, if needed, and refire the still-buried pieces, uncovered, in the kiln.

Later, although she says that the above process still works, Hadar introduced this alternative approach:

B1. Fire the pieces on top of a layer of carbon, covered, on a gas stove-top.
B2. Immediately and carefully cover the pieces with carbon, then fire them (cooled or not, either way is OK), uncovered, in the kiln.

(There is more to all of it, but we can ignore that for now….) In each case, between step 1 and 2, the pieces are fragile: you have the formed-shape, but it’s then composed entirely of metal powder with no binder holding it together any more. It’s very fragile. I have been under the impression that a few of the main differences between the A and B approaches where that:

– The full B-process takes much less time and consumes less energy than A, but…
– Pieces in the B-method are at a very slightly higher risk of being cracked as you move and bury them.

I’ve been using both, off and on / back and forth, depending on whether I had time to actually watch Phase 1 (B) or didn’t want to watch but could wait longer (A). All the pieces photographed for this post were fired, in a single batch, using the B-process. Two of the three oval pieces (above) were polished up a bit after being fired in the same batch; the third one (left-most) and both of the two round pendants are shown just as they came from the kiln. The thing you can’t really tell from a photo of the two “draped” ones is that they feel, oh how to say this, sort of “crisp”!?

Yes, and the point of this whole post is to admit that I’m the one who crisped them up!

As I said at the start, I had a lot of things on my mind as well as a few people doing things in my studio as I began firing these. I was carefully watching the Phase 1 firing on top of a propane camp-stove on a rolling cart. Some unexpected visitors arrived, adding to the activity in the room. While enjoying the company, all I really wanted was to finish this firing, finish answering questions, go home, and have a nice dinner. I was trying to keep everyone moving along, introducing and talking and answering questions and what-not. When Phase 1 finished, I had to figure out where to put the hot lid safely out of range of the curious visitors, as I rolled carts around and proceeded to the two-hour Phase 2 in a kiln. I got everything situated, got the kiln going, spent the next hour getting questions answered and projects finished, got everyone out of the room, and was walking back to my little “office” area to finish up some paperwork when I looked at the table next to the kiln and thought, “Why is that cup-full of carbon just sitting there?”

OH, NO! I had forgotten to pour it over the pieces after Phase 1. They were in the kiln un-buried in carbon! The whole thing with these clays is they need to be fired in a “reduction atmosphere,” that is, with the carbon reacting with the oxygen in the air inside the firing chamber and thus reducing how much of that oxygen is available to react with the copper at kiln-temperatures. How much? Well, that’s not as clear. But that’s the basic principle, the way to avoid damaging the structure of the metal….

No, NO, NOOOO! If it had just been a few minutes, well, maybe. But we were an hour into a two-hour firing. Were they all ruined? Was there anything I could do?!!

I quickly increased the amount of heat-resistant material I had in front of the kiln, put on my high-heat gloves and IR-safety glasses, grabbed a few tools, took a deep breath, and opened the kiln. One obvious concern: what might the “thermal shock” do to the pieces or even to the kiln itself?!! I whipped the bowl out, set it down, closed the door as quickly as I could. Everything was glowing! In another context, it might have been considered a lovely color, but not here. I gently poured the cup of carbon over the pieces, took another deep breath, re-opened the kiln, replaced the bowl, closed it all back up, took off the safely gear, sat down, and started shaking. What had I just done? Would it work? Should I have just given up on that load? What about the kiln?

And the phone rang. I answered it. A long-time friend, someone I talk with only occasionally, was on the line (er, with cell phone, perhaps I should say in the air?). It had been no more than a minute since I’d closed the kiln back up. (As I reached over to answer the call I was, in fact, thinking how glad I was that the phone had not rung while I was in the midst of that attempted “recovery” process! Even if I had not stopped to answer it, that would have been another distraction at a crucial moment: whew!) My caller asked how I was. I was still shaking a bit, and surprised by the call. I said, “I don’t know. I may or may not have just ruined a whole bowl-full of jewelry pieces.” He’s a sweetheart, someone who has been all “You go, girl!” about my journey down this jewelry-making path, and he launched right into some nice little comments about how “things” sometimes happen and I shouldn’t beat myself up or question my abilities, I was good at this and he knew I knew it, …. When he finally paused for a moment I said, “Thanks. I love your support here. But what really has me worried is that, between the time I spent making pieces, firing some of them once, patching them, making a few new ones, firing those …. if I’ve lost them all, then I may just have lost hours that I simply do not have to spare right now. And it’ll be almost an hour before I know how much time I have just wasted by letting myself be distracted.” Luckily, there was nothing more in danger right at that moment, so we quickly moved on to chat about other things for a while. I didn’t get the paperwork done but doubt I could have concentrated on that anyway. I did get to catch up a bit with someone who’s known me since my teens, and we talked for longer than I’d’ve given myself if I’d still been focused on … paperwork.

So, what’s the outcome?

There was one small crack in the kiln-wall beforehand, and it’s now a bit bigger. Not a serious problem, I think, just one burst of extra-quick aging. I’ll simply continue to keep my eyes on that, and hope there’s nothing more.

The three mixed-metal tulip-ovals had been previously sintered (and were just in that load having some cracks patched) all look like they survived. The patches sank down too much, which may or may not have happened anyway. I can try to polish out the cracks, or else patch the patches and refire them. They don’t seem to exhibit much in the way of the various copper-oxides that we’re trying to avoid via the carbon firings. At this point, though they may not end up being quite as strong as I’d like, I still think they may be OK.

The other two all-bronze draped pendants, well, as I said, they are crisp. The slightly-bigger, slightly-more-irregular one is criss-crossed with cracks and holes. Yes, not just cracks (which I would not have expected from in this single-metal piece) but also little holes that you can actually see light through (which I’ve never seen before, and which are too small to really see in the photo, even if you click to see a larger version). I figure that piece can go into one of my “teaching moment” displays. The other one, well, it doesn’t have all the same cracks and holes, but there’s something odd about it. Maybe it’s just the way the edges curled up, and I’ll get used to it over time, but it sounds a bit crisp too. I may hold onto it, but it’s not one I’d wear because I don’t want to “advertise” a piece I’m unsure about. I may give it to one good friend who I’m pretty sure will be OK with my saying, “I can’t sell this because I’m not sure it will hold up. But if you want it, you can have it on one condition: if/when it breaks or does something odd, give it back to me so I can what happened. I’ll replace it with something else.”

And, finally, there’s that thing about time, and being overloaded just now: which clearly means it’s time to end this post, get some other things done and write about those later on, once I’ve managed to catch my breath again. Oh, and I’m sorry this is so long. It takes me longer to write shorter pieces—to do the editing needed to end up with a shorter piece—and I’m still feeling waaaay behind. So I hope you’re OK with this rambling version of the tale….

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Color Shifts!

Posted by C Scheftic on 2012/07/25

After designing a piece, working with metal clay to create it, and firing it in the kiln, there remains another step to consider: post-fire color of the now-all-metal creation. There are lots of ways to add color to a piece, and I’m not about to go into all of them now. That is, for this post at least, I am not going to address deliberate colorings like enamel, resin, colored pencils, inks, various forms of plating, and so on. I am going to make a few points about several of my newer bronze pieces and will mention only in passing the “Liver of Sulphur” (LOS) patinas that can produce such nice (but somewhat unpredictable) colors on fine silver (and black or near-black on silver, copper, etc.)

Instead, what I’m thinking about today are the kiln-produced colors that sometimes appear on bronze pieces (and, to a lesser extent, on copper ones). Now, the thing is, they are basically unpredictable. You get what the kiln-gods decide to give you that day.

If the pieces come out a dark gray or black color, I will usually just polish that off. I wrote a series of posts in April of last year with “before, during, and after” photos using Hadar’s Clay Powders, and one of those showed pieces with a lot of this mostly-icky black coating that is best just polished off. That is why the first photo with this post (above, right), of a rectangular bronze piece, shows it all shiny: that side came out of the kiln all dreary gray except for one small, dreary, brown spot on its edge. (It was so dreary, in fact, that I didn’t even think to take a photo of it in that state.) But you’d never know that now from looking at its bright, polished surface if I hadn’t told you, would you?

Then again, sometimes pieces come out of the kiln with stunning colors. The second photo (left) shows two other pieces that came out of that same load. (As ever, a click should get you a bigger version of any of these.) When people see pieces with colors like that, they always respond with all sorts of exclamations of “Ooooh” and “Ahhhh”!

Which I fully understand. Except I know that those colors are basically ephemeral: there for your enjoyment at the moment, but nothing that will remain so brilliant for very long.

If I make a comment to that effect to the piece’s admirer, novices are often generous with suggestions. And I do appreciate the offers. While I am open to new ideas (especially since many of my students are artists with experience in other media), there’s also a good chance that I’ve already tried everything that’s being suggested, and then some…. The third photo with this post (over to the right again) shows two of the many things that one might consider trying.

Of the two pieces shown there, the one on the left has been lacquered. Notice how the nice, variable, kiln-green has all gone a sort of even brown shade, and the lovely bright scarlet has turned a much duller orange. I don’t dislike those colors; they simply are not the ones I was trying to preserve. In fact, I only rarely use lacquer on my pieces. It does provide some protection in the short term but, once it starts to wear off, then you have a piece that darkens in those spots but not in the ones where it remains. I do keep trying various kinds of coatings, here and there, just to see what happens, but they are not a major part of my routine. (Similar shifts and dulling of bright colors happen to LOS’d silver that emerges all brilliant and lovely.)

More often, I will do what’s shown on the piece to the right in that photo. That is, instead of the “high polish” of the rectangular piece, I will give it a “light polish” like this, often highlighting one or more select areas with a slightly brighter shine. I chose to include here a piece where I’d done that so I’d have an example I could show folks, later, who seem very surprised when I say that another reason the original colors are ephemeral is that, if they are deliberately polished or rubbed enough in normal wear, the colors will go away. Except that’s exactly what polishing does: the color is only on the surface and polishing that removes whatever reaction has happened there while also laying down the metal “crystals” so they reflect light in their “typical” color range. (Again, this can be compared to what happens with silver, both in the disappearance of the “kiln white” (or, in some cases, “kiln glitter”) and the dulling and/or shifting of colors from LOS or other patinas.)

Except, the crazy thing is, just like everything else involving these colors, you can’t quite count on all the things I described above. Some, yes, but not everything. Shown below are two shots of the “other side” of the rectangular piece with which I opened this post. This side came out of the kiln with lovely colors. I considered polishing the dragonfly, but decided to leave it alone at least for the short term, and grab a photo of how it looked with no post-fire treatment. Later, when I got the lacquer out to use in coating the round piece, above, I decided to hit this piece with it as well. And, here, the color shift was much less dramatic!

straight from the kiln after being lacquered

I’m not complaining: I liked the colors here and I’m glad they didn’t shift. I’m just saying, if you happen to get this the first time you try a protectant product, don’t assume that’s what you’ll get the next time.

And I also recommend learning to appreciate and celebrate ephemeral beauty, in jewelry and otherwise.

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Pushing, in more ways than one….

Posted by C Scheftic on 2012/07/18

About a month ago, I wrote a post about some pieces I am calling “Push Pendants” because they are made by pushing some metal clay through a piece of metal mesh. Given that I like making reversible pieces, furthermore, if you read my last post you would have seen a photo of the “other side” of yet another one of these pushed-pieces. The first photo with this post shows its pushed-side, all polished up to a nice shine. (You should be able to tell from the shape which (un-polished) “other” side it matches there….)

They’re fun to make, and I admit the original idea was not mine. They are adapted from a slightly different project I noticed a while ago in Mary Hettmansperger’s delightful book, Mixed Metal Jewelry Workshop. The approach used by “Mary Hetts” is really simple: you make the combo, fire it, then frame it in sheet metal. (Check out her book for all sorts of other useful details!) That strategy minimized one major potential issue: as the clay is fired–both burning off binder and sintering the powder into a solid metal–it shrinks. The wire mesh does not shrink. Warping and cracking can occur in the parts that began as clay! Her process minimizes that as a problem by having you frame the sintered metal with some other solid product (e.g., sheet metal, but you could use wood or fiber or plastic or whatever else you want). First of all, you don’t get very much cracking that way; secondly, you can probably just cover up any you do get.

But I started to wonder: what if you just framed it with more clay from the start? How much of a problem could that be? What are the variables involved? How much more difficult would that make the whole task? Would it still be a good project for a workshop that included both experienced and novice metal clay artisans?

After several months of experimenting (and confirming a few of my suspicions with Hadar Jacobson at the recent PMC Guild conference), it is looking to me as though:

  • With these, it helps if you are someone who is willing to accept what the kiln gives you: they’re not totally unpredictable, but even tiny variations in construction can have very noticeable effects!
  • Giving the piece a bit of curvature, a hint of the direction in which you want it to warp, can be helpful.
  • Really thin surfaces, front or back, do tend to crack.
  • Thicker surfaces have a more complex relationship to the warping and cracking, but there are ways to minimize such problems (and to make it easier on yourself to patch cracks and refire if you find that desirable).
  • The position of the mesh in relation to the frame matters as to whether and how much the piece will crack along the side.
  • The variance in shrinkage rates across the different clays makes a difference in the patterns of shrinkage and warping in these pieces. The pattern of least to worst is predictable; the exact extent seems not to be.

I’ve had people ask me why I bother with these clays if I have such problems with them. Well, the answer is that both the explorations and the results are, overall, delightful. Most of the time, pieces do turn out fine. And some of the so-called problems that do occur are ones I’d never have with silver because it’s just much simpler and more reliable to fire. But I realize that others happen because I try things with these metals that I would never think to try with silver or, if I did think of them, would be unlikely to try because of the price of silver.

In this example, besides simply pushing clay through mesh, I feel like I am pushing the envelope; that is, I feel like I am also extending the current limits of the clay’s performance, going beyond some commonly-perceived boundaries of working with it. I find the process of exploration to be fun, itself, in addition to any reactions I have to the resulting pieces or the subsequent workshops I may teach from what I’ve learned.

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The lifespan of a no-flake-foil firing box….

Posted by C Scheftic on 2012/01/30

I folded this little firing box out of No-Flake Foil (from Cool Tools) some time last April, although I didn’t record the exact date because, at the time, I had no clue it was ever going to be worth noting.

I first wrote about this particular box in a post last July, after I’d noticed a little flurry of discussion about what people used to fire the copper, bronze, steel, or other metal clays that needed to be buried in carbon. At that time, I said it had held up just fine through several dozen firings.

I do tend to fire pieces in spurts (some weeks, nothing; other weeks, multiple loads) but, since then (especially, prior to the last “Holiday Season”!), it has survived dozens more.

The last time I emptied it out, however, during this past weekend and after it had provided almost ten months of regular service, I was sad to note that it has begun to sprout a few little holes. They are tiny and not easy to see (so of course I highlighted them with big red arrows for you in the photo!). But I know they signal the beginning of the end for this particular box.

So I thought I should note the date that it has been retired from duty as my primary firing box. My number-two box will step into that role. The experimenter in me isn’t quite ready to part with number-one yet, of course, so I’ve got it stashed away at the moment. I may try using it again a few more times, just so I can document its demise for my own information.

But, really, it’s just foil. There may be nothing more worth noting about it, except that I am amazed, and delighted, that it has already done so well for this long.

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Plan – Execute – Be Surprised…

Posted by C Scheftic on 2011/11/26

Another unplanned gap in posting here, sigh. I just did a couple of things that, I’m told, are not what others think of as typical for a grandmother. What can I say? So what if I went to visit the week before Thanksgiving? And spent part of the time helping the younger one with his statistics class? Between my schedule and theirs, my interests and theirs, it sure made sense to me.

For reasons not worth going into, however, on top of that there was also a bit of a problem with ‘net connections. I could get on, but it involved either various contortions (due to short cables instead of my usual wireless set-up) or tiny keyboard (on phone instead) rather than comfortable seating. So I just figured I’d take time to enjoy the people I was with, give thanks for that opportunity, and think about posting again after I got back to my own home. Even though, now, I’m into the crush of holiday-events, I’ll keep trying to find spare moments….

So, given those surprises, let me re-start with something else that surprised me.

Regular readers of this blog will have already seen the piece in the upper right of the first photo with this post (the one, in that photo, with the black cord). It contains a draped-disk of bronze positioned on a square of rose bronze. The other piece in that photo, in the lower left position and not yet hung from anything, includes a draped-disk of bronze positioned on a square of copper that I finished about a month later (just a few days before I headed out of town).

To summarize: both the draped disks are made from (regular) yellow bronze; the backing disks are made of either copper or (special) rose bronze. At first glance, all the colors seemed fairly close to each other: both yellow-bronzes looked the same, and the copper was pretty close in color to the rose bronze. There was just a tiny bit of “aging” visible on the older, all-bronze piece. I liked how both of them had turned out, so they were among the ones I packed up with chains, beads, stringing material, crimps, jump rings, clasps, plus of course a collection of tools, and headed south on my trip to spend time with “the kids.”

A day or so later, I took out the first one, and chose an assortment of items to hang it from. On multi-strand beading wire, I made little segments of some copper- and bronze-colored freshwater pearls, connected them with chain segments, added one of my hand-made bronze toggle clasps (embellished with a little coil of copper), and connected all the bits together. So far, so good.

The next day, I took out another assortment to work on. This time, I used bronze wire to build up little segments of goldstone beads, and connected them with bits of chain (different than I’d used the previous day). There were more events going on that day so, once I had what I thought was a good length of that, I went off to play.

On the third day, I took out the bronze on copper focal bead. I wasn’t particularly surprised that the copper had begun to “age” already, darkening more (much more quickly) than had the rose bronze piece. But I did find three surprises: (1) the yellow bronze on this piece had started to darken with a distinctly green-ish hue; (2) there were bits of copper near the draped dome that (I am guessing) must have alloyed with the bronze in that (to a sort of rose-bronze that had not been immediately apparent) and those areas were not aging as quickly, leaving them a bit lighter; and (3) that this difference (alloying?) was also visible on the flat side of the piece, where a huge “central’ area of the texture was slightly lighter too. Once I recovered from my surprise, I decided I was delighted with these changes. I finished assembling everything: two more pieces done and ready to be given the opportunity to go to new homes themselves.

As soon as I got back, these were among the pieces I delivered to the Sweetwater Art Center for their annual (and delightful) “h*oliday mART” show. If you’re in the area (they are in Sewickley, PA, just down the Ohio River a few miles from its beginning in Pittsburgh), do check it out; it’s one of my favorite local art shows each year. It will run from November 27 through December 4. (Well, actually, it opens with a preview party / fundraiser tonight, and I’ll be there!)

Posted in Learning Metal Clay, Technical Details | Tagged: , , | 3 Comments »

Foil-Firing Base-Metal Clays

Posted by C Scheftic on 2011/07/06

One question that seems to keep recurring (everywhere from individual conversations to the big, international Yahoo group on Metal Clay) involves what people use for firing their various copper, bronze, and / or steel clays, so I decided to write a bit about what I’ve been doing.

At first (~2008) I used the stainless steel “steam table” pans that were the original suggestion for this. The clays fired OK (i.e., the metals sintered), but the pans flake black crud. (I’ve seen hints that the technical term is that they “spall,” though I know that word with a slightly different connotation, so I’m not sure…) Anyway, it’s not a crisis, but cleaning it up is just one more little thing to tend to, and I’m seeking to simplify this process as much as possible.

Later on, a number of ideas for other, alternative firing vessels started to circulate. Some people fire in used metal cans (i.e., reusing the kind food comes in, which would mean having the inner plastic linings burn off as you fire them; and, while cheaper than the steam table pans, they still flake). Others suggested building vessels out of fiber blanket. Neither of those held much appeal for me: I never tried either one.

Last winter and spring, Hadar Jacobson blogged about several other options, such as building a frame out of kiln posts, drilling an opening into firebrick, and building a box from ceramic cloth and T-pins. I tried the first and third of those. The posts are easier to find, the cloth is easier to use, but neither quite fit my “simplify” goal. Hadar also talks about working with several options in the instruction manual she provides. (Aside: Her manual is useful even if you’re using other copper or bronze clays! You may have to adjust specifics of the firing schedules to fit other products, but Hadar does a great job of explaining in a simple way what’s going on, what you want to have happen, and what might be going wrong if you encounter problems.) In the past year, also, several manufacturers came out with a range of fiber or ceramic firing boxes, but at least the ones I investigated appeared somewhat high-priced to me. (Or, perhaps a better way to say it is that the ones I checked seemed high for my budget for this, so I just stopped hunting. If you have found any well-priced ones, do let me know!)

Right after Hadar was here late last winter (when I gained motivation to do more with these non-precious metal clays) I decided to try something Hadar had not discussed, and to invest in some No-Flake Firing Foil. (I got mine from CoolTools.) That’s what I’ve been using quite happily now for the last few months. It does take a little fiddling-with before the first time you use it–you do have to fold it into the box shape–and then you should fire some test pieces to verify the temperatures to use–which you should do with any new firing vessel you try (or new kiln, or new carbon, etc.). But after that, this kind of box is both very easy and much more affordable than most of the other options.

The first photo with this post shows a newly-contructed firing pan before its first use. The foil comes with instructions on how to fold this particular box, and there’s a video available on the product-page. From my (somewhat basic) knowledge of origami boxes, this does seem to be a pattern that yields a relatively large-volume basic box from a given amount of material, so I did not try to second-guess the instructions there. But I will note two things about the instructions….

(1) They provide finished dimensions for various sizes of foil one might start with, but there’s no reason to limit yourself to just those. Make a box of whatever size will fit the foil you have and the size of your kiln. (Be sure to leave room for air to circulate all around the box!) Try a few paper models first, if you don’t already have experience folding boxes, so you see how it works and get a sense for the size. But, here’s the trick: the instructions list only sizes for rectangular boxes because that’s what you want to build. Not a square!

Any rectangular box will have a sort of “flap” of material that gets folded over the short edges and part-way around the long ones. (You should be able to see it on the photos with this post.) A square one won’t have that flap. You want the flap for two reasons:

  • Those “flaps” seem to increase the stability of the box, and
  • You can fold up the corners of the flaps on one long side of the box to mark the “front”–something that’s useful when you’re putting a carbon-filled box into your kiln (and especially important with front-loaders, because you don’t want to position any pieces along the un(der)heated front edge).

(2) The instructions and video use the traditional origami trick of making two folds at the very start that you just open back up again. They simply mark the center of the sheet. If you can find and mark the center-lines yourself, you can start with that rather than those two folds. That’s why my “new” box (above) has black ink lines, rather than folds, down the center. Why does that matter?

Well, some people report that these boxes only hold up for a couple of firings. Mine have held up much longer. The one shown here has been through several dozen two-phase firings, has not been treated with any particular care, and seems to be holding up just fine.

When pressed for more information, those reporting early failures say that their boxes seem to fail along the folds. Not necessarily the center ones in particular, but along folds somewhere. Now my theory is that they are not failing after, say, two or three or four firings: I think they are beginning to fail with their very first use, but the problem only gets big enough to see after several more. If you put a hole in the foil while folding it, it will get bigger with each firing, through the heating (expansion) and cooling (contraction). So the trick is to not put holes in the foil to begin with!

Thus, I chose to not make those first two folds, which must then be reopened. You’ve got to mark the center line accurately or the box won’t come out with everything lined up right, and doing it via that fold is an easy way to mark it. So either be careful folding and unfolding those lines or, if you can find both centers another way, do that.

Then, proceed with the rest of the instructions. Crease smoothly, but not so harshly that you rip little holes in the edge. Unfold smoothly too, also with care.

And, then, enjoy the treasures that emerge after being fired in such a box…

Please leave a comment if you’ve found anything useful in this post! It’s great to hear from readers. (I can see from my “blog stats” that you are out there! But comments offer even more motivation to keep on writing these notes….)

UPDATE: This box lasted for seven more months of regular use! Since this topic keeps coming up, and I keep pointing folks to this post, I’ve decided to add a link to my follow-up post.

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To answer Coral’s question….

Posted by C Scheftic on 2011/04/28

Last night was the first part of a 2-session class at the delightful Zelda’s Bead Kit Company. The plan was to use metal clay on the first night to create our own custom-made toggle clasps and, if desired, focal beads. I’d take them back with me to fire and tumble-polish them the next day. Then, on the second evening, everyone would return to Zelda’s for a quick lesson on work-hardening and applying a patina, after which we’d select beads and make ourselves some wonderful bracelets.

One of the participants last night had a number of questions about kilns for use with metal clay. One of her questions was how many pieces you could fit on one kiln shelf. Well, the answer is, just about as many pieces as all of us made last night! Here’s one of my kiln shelves (the upper right corner has been missing since I first got this shelf…) ready to go into the kiln (though I moved Ellie’s toggle bar, up on the top row, down a little bit just before I put it in).

With firing more analytical than creative a process, if you were in the class and are looking for your piece, know that the pieces are spread around the shelf in roughly the same arrangement as participants were seated…. They’re firing as I write this. With luck (but with no promises), I will remember to take some photos of the finished pieces to share here too.

Posted in Teaching Metal Clay, Technical Details | Tagged: | 2 Comments »

Passing 40….

Posted by C Scheftic on 2011/04/09

Yikes … 40 …!

No: not the age of 40. No: not the speed limit. Yes: the price of silver.

I wasn’t paying attention to prices yesterday (busy day…) and missed it at the time, but silver crossed the $40-mark on Friday.

Then, apparently, investors convinced themselves that it really is going to keep rising, and they managed to drive the nominal price up to just a few pennies shy of $41 per ounce. (Speaking of pennies, all this is driving up the price of copper too … just not as much … yet.)

Yeah, I get the “economic theory” that drives investors to metals, and especially to “precious” metals. I just happen to think that many of the things that can be done with those materials should be even more precious. Why do “they” want to destroy the simple pleasure that can be drawn from small precious metal artwork and adornments? Why do the rest of us let them? What are the alternatives, for them and for us?

Why can’t “those people” go find something useful to invest in? Something practical? Something for the good of others too? Something that would benefit society? Something that would still be of benefit to them (yes, I understand that part) but something that doesn’t have to mean the detriment of others at the same time? Why is it you versus me?

Why can’t we revise the basic definition of good to mean only if it’s good for all?

Posted in Misc. Musings, Technical Details | Tagged: | Leave a Comment »

WPaPMC tries 14K Rose Gold Metal Clay!

Posted by C Scheftic on 2011/01/30

Yesterday (January 29), the Western PA Chapter of the PMC Guild became the first group anywhere to try out 14K Rose Gold metal clay.

A member of our chapter, Michelle Glaeser, announced the availability of this product earlier this month. This will not replace the more traditional yellow gold, but it can be a nice alternative or complement to that color. Michelle and I got to talking and the end result was that, when 14 of our members gathered on Saturday in a local library’s community room, we ended up sharing almost two packs of the stuff. Michelle kept what was left over for her own continued experiments.

Of course, the price of precious metals — including gold and silver — has been climbing lately. So we didn’t go off making big gold pieces. People brought their own creations made using their favorite form of silver metal clay. Some had already been fired so that only fine silver remained; others were still in the dried “greenware clay” state. Each participant bought a little piece (0.2 grams) of rose gold clay with which to embellish them. The open domed disk with a rose gold heart was made by Stephania; the photo shows her little heart, still in the clay state, attached to her piece of pre-fired, un-burnished silver.

Why would we fire the silver first? The basic formula for any “rose gold” involves gold, silver, and copper, and the presence of copper means that the rose gold clay must be fired in an oxygen-reduced environment. But the silver clay itself prefers to be fired with oxygen. If the silver clay has been pre-fired as usual then, once it is in its fine silver state, it can be re-fired with or without oxygen. So you can attach the rose gold embellishment and fire that new bit of clay in activated carbon, which is the easiest way to get the necessary reduction atmosphere. (There are other alternatives, if you really do want to fire the two together, but I won’t go into those here.) We had several stainless steel pans (which can take the heat of the kiln), filled them part-way with carbon, loaded our pieces (as shown), topped that with more carbon, covered it with a lid, loaded those into several of the kilns we’d brought, and set them to fire away!

When the firing cycle was complete (slightly over an hour later) we let things cool down a little bit, removed the pans, and started sifting through the (very hot) carbon for our pieces. Shown, are Dee, Donna, and Nicole searching through one of the pans.

As we found the pieces, they were laid out on a firebrick shelf for a few minutes until they had cooled down to a safe-handling temperature (as shown to the right).

Then we started examining the results. Most turned out beautifully!

Two of mine are shown at the very top of this post. Each little coil used half of the rose gold clay that I had (thus, about 0.1 gram each). My one on the left (up above) is what pieces look like straight from the kiln: the silver looks almost white, and the rose gold looks dark like the clay. The one on the right shows what happens when you burnish and otherwise polish the piece: the silver and rose gold get very shiny and bright. The darker areas on that piece are the result of applying a “liver of sulphur” patina (which turned especially colorful around the rose gold!), and then polishing that off the high points to accentuate the textured areas.

(I’m pretty sure those are Sharon’s hands, in the photo to the left, polishing one of her pieces.)

For a few, the little rose gold embellishments had come loose: with more (and very careful) sifting through the carbon we were able to retrieve those. (They can be reattached and refired.) Michelle’s earlier testing had shown that painting on thick layers of paste worked just fine; we discovered, however, that trying to be “conservative” by just painting on a very thin layer wasn’t a good idea. The way the attachment happens involves a reaction between the silver and gold atoms and, if there’s just a thin gold layer, it all sinks down into (alloys with) the silver. You need to use enough for some to remain above the part that attaches. (Well, and there may also be factors involving the exact temperature and length of the firing, but that’s beyond the scope of this basic report.) Michelle says that she saw no such alloying with embellishments that were at least 2 cards thick, and that is consistent with what we observed. With pieces that big, the shrinkage rate for the rose gold clay appears to be about 15%.

Finally, I will note that regular readers of this blog will know that I emphasize the fact that most of my pieces are fully reversible. This last shot here shows the “other” side of the two pieces with which I opened this post. Though they’re similar in design (but rotated 90° from each other) on the side where I added the rose gold (shown first), this last photo lets you see how different they are on their “other” side.

(As usual, clicking on any photo should open a new tab with a larger image.)

Posted in Guild, Learning Metal Clay, Technical Details | Tagged: , , , , , , | 3 Comments »

Approaching 27 as I write this….

Posted by C Scheftic on 2010/11/05

Yes … $27!…

So I thought maybe I could quit commenting on the price of silver for a little while. Have I mentioned that I seem to lead a rich fantasy-life?

The last time I commented on this, a month ago tomorrow, the price of silver had risen to a nominal price of $23/troy ounce. In the past month, it’s mostly fluctuated up and down between $23 and $24, but I had enough else going on that such bouncing didn’t seem to require a comment.

But the last three days, well, that’s another story. Today the price started bouncing up around $27/troy ounce: silver has had a three dollar increase in a mere three days!

Was it the election, or the “monetary easing,” or what? Call me naive (and, yes, I do actually understand enough basic economic theory to know why this next statement is yet more fantasy) but I just wish that “investors” would go find something else to play around with amongst themselves, and stop messing with real products that real people use. Having fouled up the housing market, can’t they please keep their grubby hands out of the metals market and more?!

I need to order the materials for the classes I have coming up, and I really don’t want people (especially the “new” participants via my new studio) to think I’m gouging them with the “materials fee” … which will come to waaaay more than what I make for my actual teaching (that is, for my own expertise). Sigh.

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Another week, another dollar…

Posted by C Scheftic on 2010/10/06

That is, today silver’s been trading at a nominal price that’s now up around $23 per ounce.

Spinner Disk Earrings #1Of course, it’s not just silver. Gold is approaching $1,350/oz, and platinum is close to $1,700/oz. In that sense, of course, silver is still “relatively affordable,” so I’m not thinking of making any major moves in one of those directions. But other metals are spiking too, ones like copper and tin and more. Hmmm, where might all this be going … and what’s a girl to do while it does so?!

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