Wednesday, February 10, 2010

heart broken

So, last night while creative healing I put a few copper and bronze pieces in the kiln. When I took them out, I was greated by some lovely color, But upon further inspection I noticed some cracking, then as I tried to clean them up with a steel brush - I got dust! All these chubby hearts were hard on the outside and pulverized in the middle. Looking on the bright side, because I'm all about possibilities, I can mix these lovely grains and chunks with my newly acquired Golden mediums for a lovely textured background. I've been experimenting a bit with the firing schedule to accommodate the higher temperature required for the copper. But this is new. If you fired Copper Clay, do you have any pointers or a proven firing schedule? It's a bit hard to figure what I did wrong this time, a few variables from previous successful firings. In this particular batch:
}I used up some old copper and bronze clay (stored in the same baggie, wrapped separately.
}It was kept in a cool place and seemed pretty pliable when working with it.
}some might not have been totally dry, but most were - that didn't seem to matter in the fired pieces
}used coconut carbon in a steel container
}here's where I think I went wrong. I fired it with a Ramp of 500 an hour to 1700 (way too hot even for copper) and held it for 3 hours in my Paragon kiln.
Oh well, better luck next time, I guess.


Lore said...

Did you fired the bronze and copper together or you have two kilns?

My firing for Copprclay is full ramp to 1700 and hold there for three hours.

Cherylyn Bredemann said...

I fired them together. Bronze should only go to 1550, right?

DreamSome said...

Yes, Bronze can't take the high heat copper can take. Were there pieces with both copper and bronze on them? That's the only time I would fire them together. Otherwise I'd fire copper at it's schedule (full ramp to 1700) and bronze separately at the lower temp. I am fairly new to metal clay but this has been my experience.