Convergent Series

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

Posts Tagged ‘patina’

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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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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More Mixed Metals

Posted by C Scheftic on 2012/04/14

It seems like I’ve been working forever on several mixed-metal pieces, but at last I have one for which I can write a little report.

This one contains my current-favorite three-metal mix: bronze (in the traditional yellow-bronze color, used here as the base), rose bronze (in the slightly more pink color, used here for the bail), and copper (a reddish-brown used, along with those two bronze formulas, in another of my reversible pieces, in the decorative designs on both sides).

Well, technically, all of the metals contain copper: bronze is made from copper and tin. Yellow bronze gets its color (and strength) from a very particular mix of the two; rose bronze shows by its color that it has a higher proportion of copper in its mix, while white bronze (not shown here) contains a higher proportion of tin (which gives it more of a “white metal” color that is lovely, but also makes it trickier to work with (both finicky to fire and potentially as fragile as glass in its final form) so I use (and write about) it much less often…).

The three “flower disks” overlays are, from top to bottom, made from rose bronze, then yellow bronze, and copper. The copper has begun to darken a bit, as copper will; I put the rose bronze disk as far away from it as I could–the rose one will likely darken more than the yellow bronze (which often ages to a greenish hue), but less than the copper. In the middle, the smooth surface of the yellow bronze flower seems to give a very slight hint of the copper in it, more so than does the sandpaper-texture backing of the same metal. The contrasts possible with these metals make exploring them a delightful experience.

Most of the time, anyway (which accounts for part of the delay between posts recently). The other side (photo below / left) has a brushed-satin finish. Here, the bronze base also keeps its yellow color (the reddish tint towards the bottom is just a reflection of the red shirt I was wearing as I took this photograph!), but I applied a bit of patina-solution that would accentuate the differences in copper-content among the metals in the design. The twist inlaid down the middle shows, from the top, rose bronze, copper, yellow bronze; then another twist of rose bronze, copper, yellow bronze; and ends with a tiny hint of rose bronze again. The challenge in hand-finishing this side was to get a smooth, even surface so the patina-solution would not “pool” on the bronze and appear as a smudge (or worse, the start of some rough corrosion) which took several (rather frustrating…) tries. But I kept at it, because the fun part was seeing how the copper stripes darkened just the same as an aged penny would do, while the rose bronze has a sort of dotted appearance featuring a range of hues in a slightly more yellow range.

Now, all I have left to do is to hang it! I plan to use a soft, supple, satin cord, and slip a simple larks-head loop through the bail. One question is whether to crimp metal findings on the cord’s end, and then add a jump ring and clasp, or to skip the findings and instead use a pair of sliding Chinese button knots (thus, making its length adjustable). I’ll answer that once I’ve decided which color of cord to use. (From different sources, some are harder to knot than others: O the tension between artistry and practicality!)

I bet you can understand why I call this piece Three Flowers with a Twist.

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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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What I did last week (part 2…)

Posted by C Scheftic on 2012/01/23

OK, so why did I go off making those domed disks described in my last post? Well, I started them as soon as I received this photo in the mail:

That’s not a piece of mine. It was made by the very talented Maria Richmond, and it was included in an email from the delightful Zelda’s Bead Kit Company, to illustrate a workshop that Maria was to teach there last week.

I’ve wanted to take one of Maria’s workshops for quite some time now; but never managed to have both time and money available to coincide with the projects of hers that interested me the most. But when I saw this one, I contacted her right away, to ask about the size of the disks, and learned that they were some “antique enameling disks” that Maria had bought online to include in the materials-kits for the sessoin. Yes, they are very nice disks, and it’s great that they are now going to good use. But I saw that bracelet and immediately pictured making it with hand-made, textured domed disks, designed and developed using metal clay techniques!

Thus the little collection I made last week: two different metals (copper and rose bronze, from Hadar’s metal clay powders), some of each in two different sizes, all with a deep “rose” pattern on their convex (domed) side, and with either a much finer “rose” pattern or a shallow “fern” or “swirl” on the other (inner, bowl) side (varying in such a way that I could easily tell which was made from which metal). I made those to take to Maria’s class, about twice as many as I thought I’d need, plus a few smaller ones in case I needed some minor adjustments in length.

Now, my larger pieces are slightly bigger than Maria’s disks, and my smaller ones were not quite as big as hers. It looked like five of my bigger ones would come out to just a smidge under six of hers, which seemed like a size I could wear. So I just used those, rather than try to tweak the length any further by varying the size of the pieces.

Following Maria’s instructions in all other regards, the photos to the left and right here show how my bracelet came out. I was delighted.

Maria’s sample, and all of those made in the workshop except for mine, were made entirely of copper elements (not just the disks, but also the coils, links, jump rings, and clasp pieces) and, as a last step, darkened with Liver of Sulphur (“LOS”). I chose, however, not to use LOS on mine. I figured that would overpower the kiln-colors that I liked; the metals will darken soon enough on their own with age.

Then, a few minutes after I finished mine, as I looked at it on my arm, trying to decide which side should face out, I had a real “Aha!” moment. I took it completely apart and, when I reassembled it, I alternated both metals (rose bronze – copper – rose bronze – copper – rose bronze) and the orientation of each piece (rose up, coils up, rose up, coils up, rose up). I then bent the wire-wrap connectors a bit to encourage everything to lie in a particular orientation.

But, even if it rolls up and down my arm, this way I am more likely to have some elements land wire-coil up, and others, rose-dome up, thus featuring both Maria’s wire-work idea and my own metal-clay approach, respectively. (We’ve already discussed the possibility of jointly offering something along this line as a two-part class later in the year.)

And, yep, it’s a two-sided bracelet. Somehow, I just can’t help but make fully reversible pieces. Stay tuned: I’m hoping to find time to finish up yet another variation or two on this in the next week or so.

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What I did last week (part 1…)

Posted by C Scheftic on 2012/01/22

The simple answer to, “What did you do last week?” would be, “I made up a handful of textured, domed disks to play with.”

In the rest of this post, I’ll discuss (with illustrations) just what I did. In my next post, I’ll explain why I did that. I hope to add another post, eventually, where I’ll review a few little tweaks I just happened to add to the plan…

I didn’t think to stop and take photos of the earlier stages in the construction of these pieces. Mostly, it was just the usual routine for working with metal clay. I began by mixing up small batches of several of Hadar’s metal clay powders that I wanted to use. The clay was then rolled out, textured (in general, on both sides), cut, shaped, dried, drilled, and in just a few cases, further “refined” (e.g., a few pieces had their edges sanded down just enough so the final result would be even and smooth) before going into the firing pans.

At this point, I started taking photos. (I have found myself tending to take a quick snapshot of each shelf or pan as it goes into the kiln. That way, if anything seems odd afterwards, I’ll have a record of what was where. Though, my usual load involves one-of-a-kind work; with so many similar pieces in this load, that isn’t going to tell me very much, is it? Oh, well.)

This photo shows the thirteen pieces I made. Ten are basic domes. The other three (to be discussed later) are the ones with little wire loops attached to them. (Click on photo to enlarge it, if necessary, to really see any such details….)

The pan to the left contains pieces made mostly using quick-fire copper clay; to the right, mostly using rose bronze metal clay. (One or two of each also contain some pearl gray steel, but those are the ones I’m going to hold off discussing for a while yet.)

The next photo shows two of the copper domes, just as they came out of the kiln. Note the lovely color on the one to the right (convex side up). That was a surprise! (And it’s what prompted me to start my tale here, with the disks themselves, rather than just with how I used them.) I am not used to seeing much color variation on fired copper, at least not seeing it as vividly as I often see with the bronzes. My fired copper usually just looks dark, like the one on the left. Several (though not all) of the copper pieces showed delightful color this time. And the brightest colors all appeared on the convex sides, the side that I had placed face-down during the firing.

This next photo shows two other copper pieces, less colorful from the kiln, and therefore all polished up to a reasonably bright shine:

Here are four rose bronze domes, straight from the kiln. Again, these all show the side I’d fired face-down. In the past, when the bronze pieces came out with colors, it has seemed that the nicest ones seem to appear on the side positioned that way. (Though you can’t count on seeing that at all: you just have to be thankful when you do!)

Then again, this time I noticed some pretty interesting colors on the sides that were face-up as well! The pieces shown in this next photo are just the same four, from above, turned over.

A side note: All thirteen pieces had the same “rose” texture on their convex side. The other side, however, got a slightly different treatment, depending on which metal I was using. I wasn’t sure how much I might care to know which was which as I was later working with them, but that seemed a simple yet unobtrusive way to distinguish the different metals if I wanted to quickly tell them apart.

Here are a couple more rose bronze disks. On the piece to the left, note the little red dot just to the left of the hole at the bottom.

Now, I admit, I didn’t note anything particularly memorable about that dot, itself, until I turned the piece over. Hmmmm. I wonder what tiny bit of something got into my carbon, to create the little, tan “washer” image on this side? You should be able to see it clearly at the bottom of the piece here on the left, just to the right of the hole. Its center matches the position of the red dot.

Well, I’ll never know the answer to the question of what caused that. But, here, you can see all ten disks after I finished polishing them up by varying amounts:

Knowing that the kiln-induced patina-colors are rather ephemeral, that they’ll wear off the high points, at least, as the piece is touched, worn, jostled in a jewelry box, etc., I decided to polish that off all the high points on the convex sides, while still leaving some down in the hollows. (I did give a full polish to a few select pieces that did not show much range in color.) Then I fully polished the concave sides—for several reasons, the decision to go for a full shine there was somewhat beyond my control. Partly, it had to do with how I intend to use these (see my next post). Also, it was due to the polishing tools I have that made it easy for me to limit what I’d polish on the “outside” to just the high points, but that meant I pretty much had to do a full-scale polish down in the “inside” anyway (or else, spend a lot more time on these than I thought they warranted). That was fine. I am happy with the results so far.

Please stay tuned to see what I’ve begun doing with these….

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Speaking of color, again….

Posted by C Scheftic on 2011/12/02

Several posts ago, I mentioned that I was thinking of polishing this piece up, more than anything to see just what color the “rose bronze” would turn out to be. As a quick reminder: that’s the only metal I used in the construction of this bead.

The other reason, of course, is that any such patina-color (whether produced by heat, chemicals, or any other method) is still somewhat ephemeral. Since I’d been undecided about polishing it, I hadn’t applied any sort of coating in an attempt to hold the coloring a while longer, and the colors on this rose bronze had darkened noticeably after only a very few weeks, until it was much darker than shown here.

So I had a go at it with some of my favorite little 3M radial bristle disks. I think it shined up nicely!

I should probably also note that one advantage of a nicely polished surface is the way that finish is relatively easy for anyone to maintain over time.

And, I admit, I didn’t go “all the way” with that polishing here either, because I was hoping to keep just a hint of the rainbow-colors that the kiln-firing had produced. And, so far at least, that hint is still there; along the edge of the folds of the layered side, and along the left edge of the side with the coils. Hooray!

Time to send it off to a holiday show, and hope it can find a happy new home with someone who will take delight in wearing it.

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Speaking of metal-colors

Posted by C Scheftic on 2011/11/30

Writing my last post got me thinking about metal-colors, so I thought I’d post a few more pictures.

The first photo, at the right, shows a piece with alternating strips of copper and bronze. (In two places, there’s a mixed-metal layer sandwiched in there too, where I used clay containing small, leftover scraps of copper and bronze kneaded together: can you spot them? Click the photo if you want a larger image.) The piece was polished pretty well although, given the tools I have available, the only way I know to get it super-shiny would have also obliterated the slight waves between the layers, so I made a choice when to stop. I wanted to leave a bit of the natural variations between the alternating strips, and I’m happy with the slight satin finish overall.

After a good polishing, it’s almost impossible to distinguish the different metals. So I then used a product called Baldwin’s Patina to bring back the contrast between the polished metals. The copper should continue to darken, very slowly; the bronze may eventually age a bit too, but that should happen even more gradually.

The second photo, left, shows an all-copper piece I made several weeks later, another one of my “draped metal” designs. Can you tell I’m having fun with these?! It’s especially delightful when I work with Hadar’s copper clay, since that one has a texture that feels almost like silk: soft and luxurious to work with!

The draped portion has a very light, random, texture (from sandpaper). After being fired, it was given a light polishing (with those 3M radial bristle disks I’ve mentioned in some previous posts), and then left to age naturally (much as a copper penny will darken over time). At this point, the shiny ball elements do seem ever so slightly paler than the textured area. Overall, however, the piece has darkened more (more quickly) than has the smoother, patina-treated piece shown above. Go figure….

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Just a hint of color.

Posted by C Scheftic on 2010/01/14

Metal-smith and metal-clayer Tim McCreight is in town, teaching several workshops at the Society for Contemporary Craft.

One of them is "PMC & Color."

I made a whole collection of small pieces, mostly simple charms, to color-up in the class, the idea being that they could end up on some sort of sampler piece, perhaps a charm bracelet.

Some of them turned out beautifully, a few did not react quite as I’d expected, and some remain to be finished. Tim covered a whole range of possibilities, but there wasn’t time for everyone to complete samples using every method that had been addressed. Each participant did have time to try out a few of the ones that captured their interest the most.

Charm: Copper-clad and ammonia-fumed.

One of my favorite methods involved copper-cladding. In this method, you use a bit of chemistry and a bit of physics, and what you end up with is a piece that’s covered in copper.

Now, why on earth would you take a piece of (relatively expensive) fine silver and cover it with a layer of (relatively less expensive) copper? Because, even if you like what are known as patinas, there are only a limited number of options for getting patina colors on silver. But copper is another story: there are all sorts of recipes going back centuries for getting patina colors on copper. So you coat (clad) the silver with copper, selectively remove portions of the coating, and then color what’s left.

Did you notice the copper on the image above? It’s there, in the hollows: it’s what’s been turned (by exposing it to ammonia fumes!) into the areas with that blue-ish green color!

I did not polish the copper off the the back before starting the development of the patina. So, um, it turned mostly black!

Clad and fumed, the back/bottom turned black! Clad, polished, fumes, and polished some more.

Not to worry though, it’s still easy enough to polish most of it off. Since these are just simple charms, on the other hand, I didn’t feel compelled to remove every last dark molecule.

Over the next few weeks, I’ll try to post more examples from this class and my follow-up experiments.

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