Convergent Series

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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.)

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