Wednesday, March 03, 2010

Bronze firing experiment

So....I knew this would happen. A couple of weeks ago, I posted that I was having trouble firing bronze clay. The last few batches did not fire/sinter correctly. What came out of the firing pan was basically a pile of bronze dust.  At the time, I couldn't think of anything that I had done differently. I hadn't.

This time, I made up a batch of worry beads, let them air dry for a few days (actually about a week before I got around to firing them), and then fired them using the exact same batch of carbon, in the same pan, and using the exact same firing schedule.

Guess what? Perfect. All fired beautifully. I'm at a loss for what's going wrong. Planets out of alignment, the kiln gods were being good to me - who knows? My kiln is fairly new, so I really don't think there is a calibration issue. Older kilns are known to have that happen, but as far as I know, it's not a sporadic thing. All of my silver always fires just fine, my copper always fires just fine. It's just the bronze.

I'll keep posting everytime I do a bronze firing - we'll see. I really, really like the bronze clay. I'd love to know what the problem is.


Carol Tannahill said...

Thanks for the info. I've been thinking of trying out the new metal clays and now know this may not be a good beginner metal. I'll practice on something else first.

jen said...

Hi Carol,

The copper clays from both manufacturers are foolproof - I would start there!

alutz16 said...

hey jen, I have made two beads with bronze and clay cork in the center. both just crumbled in the kiln. (two different firings) any thoughts? is cork clay incompatible? the second time, the other pieces in the kiln were really over fired looking. you know that bubbly texture and the details were gone. thanks!

jen said...


I'm not sure about the cork. I'll have to try that and see what happens. I do have some cork already dry, so I'll try to make that my bronze experiment of the week.

What was your firing schedule, and what type of kiln do you have? Also, another thought. How long did you leave to bronze to dry before firing?

alutz16 said...

the cork had dried for more than a week, but the final product only about 18 hrs, but on a mug warmer. (this was the second one) the first, the cork was pretty fresh and the bronze was less than 24 hrs drying. I ramped 250/hr to 1550 and held for 3:30, just like is recommended in the bronzclay brochure. then, last night, I did another piece without cork, and did the recommended 500/hr to 1550 for 3 hrs they say for thinner pieces. it turned out okay, a little speckled, and it shrunk a ton. but good enough to finally deliver to my patiently waiting customer! I would love to hear about what you get in your experiment. oh, and I have a paragon, top loader (caldera)

jen said...

It sounds like it should work ok... I'll have to try the cork this week and let you know. Hopefully, I'll get a chance later tonight to work on them.

I was sent this link for firing as well, (shh,,,we'll pretend for just a minute that I'm not linking to the competition). It seems to leave the pieces uncovered for the first stage of the firing.