Working in base-metal clays is actually a lot of fun. Just as addictive as working in silver metal clays with out the expense. Especially since the silver market seems to fluctuate more than the cost of a pack of metal clay.
One of the frustrations I had when I first started working in bronze and copper was that I couldn’t fire stones in place with out them fogging up or shattering.
I work with fire-in-place CZs that are heat rated for use with metal clays.
Step one: look at the heat rating for the stones.
This right away eliminated greens and most purples, since those stones could not take the heat and duration needed to fire with base metals
So I decided it was time to test if I could even use stones. I did a sample run with a variety of colors and dichroic glass. The black burned bubble is what happens to the glass.
The reds survived the process the best.
I also found something interesting, the side of the stone that was exposed to heat with out being supported by kiln padding fogged up, but the side that had been sitting on the padding stayed clear.
The underside of the red and the blue look pretty sharp and clear, but that orange and white are totally fogged.
The top of the blue and orange stones are totally fogged up
So after looking at the results of this first test, I concluded that if I wrap or pack the stones so they have no exposure to oxygen in the firing process (even less than what they will have in the carbon) they might actually keep their sparkle.
Time for more testing
These CZs have great sparkle, now to see if I can preserve it during the kiln firing process in a base metal clay
I wrapped three clear CZs in copper clay bezels. I left them sitting on top of the carbon on a platform of kiln paper and a mesh firing rack for the burn-off phase.
After the first round of firing, I carefully placed kiln fiber around two of them, and placed a square of kiln paper over the other two –after all this is testing in the name of arts and science right? Which method is going to work the best?
I covered the whole lot with a mesh cage, since I did not want the carbon to knock things about. I covered the cage in at least 2 inches of carbon.
After the burn off phase of copper metal clay, protecting the CZs with kiln padding and kiln paper
Customized cage of mesh to further protect and keep the kiln fiber and paper in place
After the firing, nerves got all twisty waiting to see the results. I was pleased that the kiln paper and padding stayed in place.
Protecting the stones from additional oxygen that is in the carbon (yeah I know the carbon removes MOST of the oxygen in the firing process, but not all) lets them maintain their sparkle.
all four CZs maintained their sparkle
This only works with heat rated stones that can tolerate the higher temperatures of the firing needs of the base metal clays.
I immediately started adding CZs to my work once I had a successful and duplicatable method. Who says art and science are separate?
