I’ve had a lot of success with firing BronzClay, but I happened to have some real disasters this week and last week, so I thought I’d photograph them and show them to you, in case you’re wondering what can go wrong in firing and why.
In these cases, I can tell you the error.
Error Number One
I use the two phase firing schedule published by Tonya Davidson on her blog. First, a fast ramp (top speed) up to 1190, hold for 30 minutes. Then a slow ramp (lowest speed) to 1516 (for a muffle kiln) and hold for 3 and a half hours.
Because my Paragon SC2 kiln is an older model, it can only be programmed for one ramp speed/temp/hold time at a time. My error was that for the first phase, I accidentally left it on a SLOW ramp. So in addition to cracking and warping, my pieces also took forever to fire!
Error Number Two
These look okay-ish, but not quite right from the front.
Here’s what they look like from the back:
As you can see, these are not fully sintered. This is the problem that can happen when pieces are dense, the outer part sinters, and you get this shell filled with powder.
You can see in one piece I poked it with my tongs and they went right through.
What I think went wrong in this case is that I tried to put too much in one container load. I follow Hadar Jacobson’s instructions for loading the container, see her blog for details. But this time, I got impatient, and tried to fire too much at once.
Now, just so you won’t lose hope, here’s a picture of a successfully fired BronzClay pendant.
I think it’s time for me to start keeping a log book of firings! How about you? How are your firings going?