Finally! Whew, that was getting really frustrating. Turns out, the problem was my kiln. This was the same kiln that I use to fire my art clay silver with no problems. However, the bronze is more finicky.
This time, I tested it out using a firefly kiln, and I ramped up 300 f per hour to 1500 f - then held for 2 hours. After which, I just shut the kiln off. The firefly I'm testing right now does not have a digital controller, just a pyrometer - Which means, you can't program it - and all changes in temperature need to be done manually, over the course of 7 hours. A digital controller is really, really needed. 7 hours babysitting a kiln is not by any stretch of the imagination fun. But I did get my studio cleaned up and organized!
The pieces came out wonderfully - perfectly fired, and sintered. Nice solid pieces of bronze!
Here are a few little worry beads I made -
I did have one failure in the batch, but it wasn't a problem with the firing, but rather with my construction. I think I mentioned before that there is a learning curve to working with the bronze - especially if you are accustomed to working with the silver clays. The construction techniques that work in silver - do not necessarily work in bronze.
Below is a hollow heart box bead that made. The box is built in three stages. Before firing, the seam was not at all visible. Obviously, my seam construction was not solid enough. I'm going to try this again being more careful - we'll see what happens.
I'm anxious to try out the copper clay now as well. My copper arrived in my mail box this morning - so by next week I should have some copper to show you!