This time I used the two-phase firing schedule recommended to me by Lora Hart. First, I fired the pieces on an open kiln shelf at 555 degrees for one hour. Then I transfered them to the firing pan with the carbon and fired them at 1670 degrees for three and a half hours. And voila! Hard, shiny copper! I'm no scientist, but I think this has something to do with the binder burning off. You metal clayers out there know that when the binder burns there's a smell, right? When I put the fresh pieces in the firing pan with carbon I never smelled that smell. When they were on the open shelf the smell started when the kiln hit about 450 degrees, just like with silver.
These from the Fern Series have a patina applied to show off the texture. I'm not sure yet if I like this. The Liver of Sulphur darkens the entire piece a little bit. The bright, shiny color right out of the tumbler looks so nice, but I don't know if that will last over time. One of the benefits of using metal clay rather than sheet metal is the opportunity for wonderful textures and when you darken the recesses the texture shows up better. With silver there's more contrast, so the jury is still out on whether to patina copper, or not. Anyone out there have an opinion on this? Please leave me a comment on this, and links to photos would be great to help me make up my mind.