A couple students in my metal clay class have, at different times,
had the CZs they embedded in their pieces turn cloudy. Other CZs from
the same batch in the same firing are fine.
First, the only difference I can pinpoint is that, in the recent
occurrence (I don’t remember about the previous case), the piece with
the problem was fired on a pellet made out of investment to control
shrinkage. So I’m thinking that the investment may have given off
fumes in the 1650F firing that affected the CZs. Does this seem
possible? These were both fairly long firings, as the kiln is brick
and well-insulated, and stays hot a long, lon= g time if not opened,
which it was not until the next morning.
The other question is, what is the best way to remove the CZs? How
hard will they be to break apart? We can, of course, try to peel back
the fairly thick fine silver around the stones, but I’m concerned
about damage. I’ve never removed a stone from fired metal clay, and
would be happy to have input.