Copper and Bronze clay require an oxygen free environment when firing in a kiln, so they need to be buried in carbon. A lot of instructors and websites sell stainless steel pans for this use. I've found that using a wine bottle glass mold and some kiln shelve pieces instead of the stainless steel works great!
I much prefer the molds to the stainless steel pan!
The Stainless Steel pan makes such a mess, I decided to try the wine bottle mold I had and kiln shelve pieces. The photo above was before covering with the carbon on top.
What a mess...this is what happens to steel at 1500 degrees! It flaked all over the kiln.
First firing was too hot and the pieces were a weird combination of burnt and were not sintering at all points. I had to fire three times lowering the temperature to get the adjustment right.
Even though it took some tests and trials, metal clay is such a great material to work with. It requires just a few tools and a kiln. Silver clay can be fired without a kiln by torch flame. So far I've worked with fast-fire bronze, copper and silver (PMC).
Here are some pieces that are dried, prepped and ready to be fired.
You can see successful :-) finished pieces in my Etsy shop by clicking here.