Precious Metal Clays
There is a new type of clay that actually will bake and become metal jewelry. When fired, the clay bits burn away and you are left with a metal piece. It is expensive. There is a shrinkage factor. It must be fired under special conditions but it does open a whole new world of possibilities.
sculpts like a clay, but makes 99% pure silver jewelry! The problem is, you
must have access to a kiln. You cannot just bake this in a home oven. It
needs to get to over 1200 degrees F (650 C). You might ask a local college
art instructor to fire your sculpted piece for you.
PMC shrinks quite a bit - about 30% - PMC+ & PMC3 (the newer more expensive kinds) about 12%. The neat thing about that is that after firing, any detailing you've stamped or etched onto your piece looks very finely drawn. I've seen some beautifully detailed things the local Polymer Clay Guild artists have made - tiny, delicate findings and beads that started out as much larger pieces of clay. Also, if you don't burnish it after firing it really has the mithril-y look of the Evenstar pendant.
I can tell you from experience that PMC is not the best thing for making crowns or circlets. I recently took a PMC class where I learned several important points about working with it. The most important thing being that once fired, it is not flexible. It will not "fire in shape" either. no matter what you make, the item ends up flat during the firing process. You cannot shape it afterwards either.
Your best bet on making crowns and circlets is to use a proper gauge of wiring and shape it how you want it and then add whatever embellishments you wish. You can even shape the wiring and then use pmc to make the embellishments you want to attach.
I've finished reading Tim McCreight's book "Working with Precious Metal Clay". (It's even spiral bound).
There are great tips in there on making tools for shaping in the clay and leathery stage, as well as making polishing tools, including a tumbler. The bulk of the book is projects intended to give a newby a good feel for the medium, but I skipped to the instructions and tips in the back and found a plethora of valuable information and answers to a lot of questions I had.
The percentages of shrinkage are all in that book, in fact, there is a ruler you can photo copy to show you what an inch pre-firing looks like next to an inch post-firing (for all 3 types of PMC) So that as you're measuring pieces (specifically helpful for headpieces that need to be a certain measurement) you can plan for the shrinkage.
Working with PMC
The trickiest part is learning how to burnish/polish/finish it once it's done firing.
The rest is just using play-doh skills (or any other sort of clay medium) and letting it dry thoroughly before firing. Also, once it's dry (not the leathery stage when it's about 10% water still, hard as a rock dry) you can sand the edges so that you get nice smooth crisp edges that you wouldn't necessarily get with sculpy or something of the like. I have a feeling I'm going to be incorporating my Dremel on this quite a bit (expecially with the polishing post-firing, I don't particularly want to work through 20 grits of sand and polishing papers to get it to the right shine, Dremel will make it much easier).
This clay originally required a kiln to fire the clay. However, that produces limits for many folk... both those who have access to a kilm and what size piece they could make. Firing options have increased for some clays.
I found all the nifty new info: http://www.silver-clay.com/nmclay-bin/shop1.pl/page=firing.htm/SID=1091681619.22021
this site also sells 24 kt gold paint brush on & fire ,they sell PMC,PMC+,PMC3 and a product called "ArtClay" by Aida, also fires silver.
If you're lucky enough to have a bead shop near you that offers classes, they might have one for PMC.
Out on the web
Thanks to Morgaine, Melody and all the others that are contributing new info here.
This page was last updated 04/22/08