Convergent Series

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

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.]


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: