Slimping into Terra Cotta Mold.....

Stuart Clayman · Post by **Stuart Clayman** » Wed Jul 09, 2003 12:09 am

I found some old molds at a studio and I tried them.. the slumped pieces came out with a matte finish on them... not devit.. just matte.. can anyone tell me why?

Brad Walker · Post by **Brad Walker** » Wed Jul 09, 2003 6:16 pm

Top or bottom?

Stuart Clayman · Post by **Stuart Clayman** » Wed Jul 09, 2003 8:44 pm

Top. The bottom was as I expected it.

Ron Coleman · Post by **Ron Coleman** » Wed Jul 09, 2003 9:31 pm

It may be evil vapors from the molds if they have been sitting around for a long time. You could try firing them high (1500) without glass a time or two and see if that helps.

Ron

Stuart Clayman · Post by **Stuart Clayman** » Thu Jul 10, 2003 1:01 am

Ron,
You may be on to something... Evil Vapors? ... PLease explain.. the molds have been sitting around for a long time. I got them from a studio that had not used them in years.

Stuart

Ron Coleman · Post by **Ron Coleman** » Thu Jul 10, 2003 8:02 am

Evil Vapors or outgassing from the molds may be caused by surface contamination or something absorbed into the clay over time. It's hard to tell what it may be.

I always like to throw experiments in the kiln while other things are firing just to take advantage of the extra shelf space. I have found that firing any kind of chemicals (like copper carbonate) exposed to the kiln atmosphere can fog other glass in close proximity.

Ron