Convergent Series

learning, using & teaching metal clay, and other aspects of life

Posts Tagged ‘oops’

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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Following Up with Alice.

Posted by C Scheftic on 2012/05/12

Or maybe I should call this post “Slipping Up…”?

Though I hope others find something of interest in this note (like my last post, another example of a piece that just evolved during some demos), my reason for writing about this one is a little exchange Alice Walkowski and I had early this year about a technique (borrowed from the pottery world) called slip trailing, some of which may be found among the posts here (on her blog) and here (on mine).

But, let’s start with the first photo. I had cut the “sunshine shape” out of bronze during a demonstration. At the time, I was making several points. One was about taking care at corners, points, hollows, and such, (regardless of whether you used (my favorite) press-down cutters or (as books and articles often describe) drag-tools with templates to make your cuts). Another was about how, if you had a texture sheet with several different designs on it, you could sometimes get an interesting look by letting the area you cut out cross over from one pattern into another. Because I was focusing on all that, I did not bother to texture the other side before I cut it out. But I liked the result enough that I didn’t continue, as I often do in demos, with just squishing my clay up to reuse later on: I kept it, and let it dry as it was.

As I also reported recently, I’d demonstrated several examples of making and then joining links “invisibly” so I had a pair of linked rounds lying on my worktable. I added them to the “plain” side of the sun-shape. Again, I included my little talk about how, although many metal clay artists would use paste for the connection, I don’t get why so many people do it that way. I use plain water plus a brief moment of patient pressure (no longer, overall, that opening and closing a jar of paste…) and, neat and easy, it works just fine!

Then, someone just happened to ask me about slip trailing. They’d read about it, but didn’t quite get how it worked. So I moistened up some rose bronze clay, and used that to fill an empty, clean syringe so I could start to show the process. But, as can happen in quick, impromptu demos that get me off track of what I was planning to do, I didn’t pay as much attention as I should have to the thickness of the moist clay I was loading into my syringe. And a big “plop” landed on my careful (if quickly-sketched) design, covering several “rays” all at once.

I cleaned it up a bit and then tried, without as much success as I’d hoped, to add a dainty “plop” on the other side, to at least offer a bit of balance to the piece. But it just seemed to continue its own ungainly theme….

Refusing to acknowledge any sort of crisis regarding my lovely textured-star shape, I explained that piece was just telling me what it wanted. So I dribbled on some more goopy rose bronze and then added a few “highlight blobs” of copper clay too. The end result is more “turbulent” than what I’d planned to do, but I decided to just fire it anyway and see what happened. And I think the “stormy” look is just fine, especially in contrast with the precisely-textured first-side. Two different looks in one piece, as I often say!

And besides, by that point, what other reasonable choices did I have? I hope it will find a home with someone who can appreciate the mixture of precision and wildness across its two sides. Some may not, but I’m sure a very special person will, in the end, resonate with it!

(By the way, I did do a second demo using another base piece I had on hand, showing how the results can vary with different consistencies of slip. Much more successful! For reasons not worth going into here (though Alice knows at least one reason why…), I haven’t yet managed to capture a photo of that piece.)

Posted in General Techniques, Teaching Metal Clay | Tagged: , , , , , | 2 Comments »

What I did last week (part 3…)

Posted by C Scheftic on 2012/02/01

Well, by the time I’ve managed to get around to posting this, I’m really talking about the week before last, but I figured I’d keep the same basic post-title I’d started this series with, and just keep going.

After writing last week about making some textured domed disks, so that I could use them in a bracelet inspired by Maria Richmond, now I’ll talk about how I’d imagined completing the project with an idea inspired by a post by Hadar Jacobson about making magnetic clasps from steel metal clay.

I thought I’d do pretty much just what Hadar suggested. The only difference was that I used a textured layer of her rose bronze clay, rather than the smoother layers of yellow bronze and copper she showed in her instructions. I draped that over a dried layer of her pearl gray steel. After letting it all dry, inserting a bronze wire bail, and “refining” everything, I fired it as recommended.

The rose bronze cracked. The steel under-side (not shown) seems fine.

I tried again, this time using textured copper draped over pearl gray steel.

Again, the steel under-side (not shown) came out fine but, also again, the copper over the top cracked.

I patched and otherwise repaired all three pieces, and refired them.

You can see that much of the wonderful kiln-induced coloring disappeared. (Compare that photo to the first two above; the colors were also mentioned in part 1….) No crisis there. One copper piece (top, above) shows only a tiny bit of cracking, at its edge. That’s not ideal but, at this point, I’m likely to leave that alone because, sigh, the other two came out worse than before! What happened? My guess (and this is only a guess), is that the steel (which sure had seemed to be sintered) had sintered some more (that is, it became denser and thus shrank some more) and the movement associated with that further shrinkage in the steel is what led to the additional cracking in the copper or bronze layer.

If I’d known that was coming, I could have measured everything much more carefully at each step along the way, and used that as a way to test my hypothesis (i.e., the guess, above). But I didn’t know; I just didn’t think to stop and take the time to measure….

Since I’d been stuck with refiring anyway, I tried a couple more. Shown, below, are the initial results from again using rose bronze and copper, respectively, but this time draped over clay made from Hadar’s newer Pearl Gray Steel XT powder. (They differ in size because I made my original textured dome elements in two different sizes as well; I point that out simply so you won’t think any difference you see could be due to variations in shrinkage. That was just my own doing….)

OK, much better! Much less cracking with that mix! Again, sanding the steel on the other side shows that it appears to be sintered. I’m not about to test that by refiring either of these. I’ll just live with a few hairline-crack issues on these pieces; all that means is that I’ll have to think especially carefully about how I use them.

Sometimes, even when I don’t think to do pre- and post-fire measurements, I do still come up with “Plan B” ideas. So, while I was at it, I made a couple toggle clasps using Hadar’s regular (i.e., yellow) bronze powder, to put in the box when I was (re-)firing the other clasp elements. Again, they were made in two different sizes. Their textures, curvature, and size match the domes I made to use with the coils; I added a heavy-gauge bronze wire loop to the toggle bars. In this photo (and the last one above), I show them after firing and after I’d brushed them just enough to confirm that they’ve sintered. I’ll shine them up a bit more before I go to use them in a piece.

Though none of the pieces from my last firing show the lovely kiln-coloring I got with the earlier batches, I do believe that there will be enough acceptable elements in all this that I can finish off my first round of bracelets with a few components left over. Earrings, perhaps? Or the start of a necklace?

[Update: I just added the “oops” tag I’d oops-ily omitted from the original post.]

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It’s always something, isn’t it?

Posted by C Scheftic on 2011/11/12

Sorry I’ve appeared quiet here lately: It’s busy-season once again. Why do the peaks of show-prep and garden-season always coincide? Both spring and fall! Life is pretty full already, on an ongoing basis, but when the crunch-times hit, well….

Anyway, I’ve been busy, happily-busy but busy nonetheless, building up inventory in advance of the special holiday-sales season. And, as I mentioned in several previous posts, working in non-precious metals seems to ramp up the time-commitments even more, with extra time in clay prep, kiln-tending, post-fire finishing, and such.

Plus, there are always surprises. I was making a number of “focal beads” in a range of combinations of copper and various bronze formulations, and thinking about how I would hang them. So I decided to stock up on a few hand-made bronze toggle clasps while I was at it. Five are shown in the first photo with this post, above.

Basically, that’s what they looked like straight from the kiln. The more-metallic looking one (upper right) was given a quick polish (with one of the 3M radial bristle disks—if you want technical detail, ’twas the yellow one @ 80 grit) just to test whether it had sintered properly. I’ll get around to giving all of them a proper polishing as soon as I can.

But the thing about time and surprises and such is this: one of the five toggle bars I made to accompany those came out with a big crack. (See the lower-left piece in the second photo, which was enlarged a bit to show more detail.) And, of course, it did so in the last batch I’d planned to fire at the moment using the usual “bronze” schedule. (A copper load is ablaze as I write this, but bronze will melt at copper temperatures….)

The crack is mostly aesthetic. That is, there’s enough still holding that I’m not worried about its breaking. It’s just that I have to patch the crack — which will both make it look right and further strengthen it — and then refire the whole thing. Though that’ll mean hours-more of kiln-tending… Might as well sink time into making a few more piece, and fire them at the same time while I’m at it…. That, of course, is part of the “addiction” of working in this medium!

And then I’ll start assembling elements, deciding which clasps I want to go where, and polish and/or patina them as appropriate to where they’ll be going.

The re-fring is not a crisis. It’s just another one of the seemingly infinite “time sinks” this time of year. When I really want to be out in the lovely autumn light, playing in the gorgeous fallen leaves. Will I ever get far-enough ahead to manage something like that?

[Update: I just added the “oops” tag I’d oops-ily omitted from the original post.]

Posted in Misc. Musings | Tagged: , , , , | 1 Comment »

Another curious little surprise.

Posted by C Scheftic on 2011/05/25

I noticed something in my studio yesterday that, once I got over the surprise, did actually make sense in a way I hadn’t thought about before.

In several other posts, I’ve mentioned that I like making pieces where I weave together bits of metal clay that have been specially treated so that the resulting dried “greenware” remains flexible.

Well, I recently made several pieces using that technique applied to copper, bronze, and steel clays too. I’ll post about those pieces eventually, I’m sure, but it’s the leftover materials from those that are the focus of this post.

With silver metal clay, it’s fine to just leave lying about the dried greenware (whether it’s of the hard or the flexible variety). Dried pieces can just sit there waiting to be fired, and extra bits of dried but still flexible greenware can be left alone waiting to be used in some future project. (Leftover moist clay should be sealed up securely, so it remains moist for future use. Care should be taken with leftover moist clay to prevent it from becoming moldy, but that’s not my point here either….)

With copper and bronze clays, you can leave dried pieces around for a little while, waiting to be fired. Maybe not as long as with silver, since the outer layer will begin to oxidize (tarnish) eventually, but it’s not like you have to rush to get the stuff into the kiln. (Besides, since you can fire fewer of these pieces in a single load than you can with silver, it doesn’t take as long to accumulate a “full kiln load” as it does with silver … though sometimes it does take me a while to find the time to tend to the more complex firing schedules with these clays.) The same seems to be true of stuff that’s been treated to form flexible greenware. It will remain flexible and usable for some time, though not forever. Moist clay should be sealed up very tightly: in addition to preventing evaporation of the moisture in it, you also want to reduce any possible reactions from exposure to atmospheric oxygen and pollutants. Luckily, freezing of any of the moist or dried clays in this family seems to help reduce the oxidation that can form as a result of even limited exposure.

But steel, well, that’s a different beast. It doesn’t just tarnish, it can actually rust, so finished pieces require some extra treatments to help reduce that. But here’s the bit that surprised me when I first saw it, but not once I’d thought about it: specks of rust can form all over any pieces of flexible greenware that are left lying about! Even if it’s only been for a few days, the trick to flexible clay is that it never really dries out and, of course, damp steel will rust for sure….

Shown below are “left over” pieces of flexible greenware. In order, they are: copper, bronze, and now-rusty pearl gray steel. Sigh.

I guess I’ll have to try freezing any leftovers from the next batch I test out, to see how long that holds up.

Posted in General Techniques | Tagged: , , , | 2 Comments »

It seemed like a good idea at the time…

Posted by C Scheftic on 2011/05/21

… but bronze and copper shrink at different rates that sometimes yield surprises.

If it had turned out OK, I’d’ve been torn: should I polish it up to an even, satin finish, or just leave it with this colored, antique look?

I can try to patch it but then, for several reasons, it’s almost guaranteed I’ll have to polish it. That’s ok.

I was, however, making it in the hope of meeting a deadline that I’ve now missed, so I’m going to Plan B for that and will set this one aside for the time being. I’ll come back to it later on. There’s a story behind the design, that I’ll tell when I’ve worked it all out.

But this is such a dramatic image, I couldn’t resist posting it. (FYI, this piece is the reason I’d mixed up a big batch of bronze, whose leftovers I described in my past few posts.) Sigh.

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