I scored an old electric potter's kiln in the mid-'70s. I had to do a bit of rebuilding, but it was soon working, and I immediately tried firing my baskets like a potter would a raku vessel. I was told by a good friend, a metals professor at a well-respected art institute, that the heat required to provide a permanent color change would cause my woven forms to collapse. In time, the repeated opening and closing of the kin would destroy it. I did not listen. I proceeded to experiment. Forms did collapse, and the kiln was frequently in need of repair. Eventually, I discovered a way to consistently judge the metal's temperature by its color while in the kiln, and I learned how to remove the woven forms and quench them before they collapsed.
The most challenging surface color to achieve was black because the temperature at the metal's surface had to close to 1800 degrees. At that temperature, the weaving didn't merely collapse; it self-destructed, leaving me with a pile of unusable copper shards. I eventually discovered the trick to the crusty black surface I desired over several years and several kilns. When I showed one of my first crusty black baskets to my metal professor friend who said years earlier, it couldn't be done; he answered simply, "It's a good thing you didn't go to art school. You would be doing the work you're doing now."
Recycled materials, woven copper, brazed, fired silver oxide patina, polychrome 11" x 11" x 9."