Saturday, March 14, 2009

Bronze Clay in Italy

We spent the first two and a half days of the workshop on bronze clay. The primary bronze project was the bracelet that Louise will teach again at Bead & Button:

My attempts at these thin links verified what I've experienced at home: work thicker in bronze than you would in silver. I thought that I could get away with 4 card thickness with a tear-away texture, but then I got inspired to carve the edges a bit and almost every link cracked somewhere. Louise's philosophy is that bronze just requires repair, that it is a step in the creation. I'd prefer to just work thicker and not need to repair and refire, especially with the long firing times.

Firing was a primary issue that limited what we could do. The firing schedule we used was one recently developed by Hadar Jacobson, requiring a fast ramp to 1000°, 100°/hour to 1100°, then a slow cool, followed by another fast ramp to 1530°, held for 2.5 hours. Because of the electrical wiring in the villa, we could not run the kiln and the dishwasher simultaneously (we blew the circuit breaker the first night we tried it). That limited our firings to on average only one per day, working around the dishwashings which were deemed higher priority.

Since we were constrained to a single layer, the box didn't hold a lot of pieces. A couple of students got their bracelet links all fired in the first few box loads, but it took several days before I got anything to show for my efforts. Then a few links went into each load over several days, so that my links exhibit at least four different patinas. And the worst broken links were totally black, but came out more colorful after repair and refiring. This will be one of the first things I do after getting home: refire them all together (after I fix a few more breaks) to make them coordinate before I do the jumpring assembly.

Other pieces I tried included a small bell made from a cutoff hollow lentil, which cracked through where I'd carved it, and didn't fully recover after one repair job. This would simply not be an issue if I'd only worked thicker. You can see the sunken area at the upper left.

The two domed circles I carved that were thicker survived well, although one was in the black patina batch, so got a brushed finish.

We also made a bangle bracelet from a coiled snake. Mine was too thick and didn't sinter properly and broke open. I had the option to do a quick, dirty repair for refiring on the last day, but chose to just bring it home as is. I decided that the knobs I added (terracotta looking in the photo), which are big relative to the bangle to account for shrinkage during firing, just don't suit the bracelet anyway. I think it's probably just easier to remake the whole thing than to attempt repairs. Maybe I can cut a section to use for something else.

Anyway, that was 2.5 days of work. Overall, my assessment is that bronze clay is still a big mystery. I did get to try Hadar's new bronze and copper clays later in the week.