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weird copper carbonate

updated wed 29 apr 98


Dennis Davis on tue 28 apr 98


Thanks for your reply. I had suspicions that the copper carbonate particles
might be contaminated with some oily substance and therefore would not
disperse. I did think of trying a bit of detergent in the glaze. Another
thought I had was to heat the copper carbonate and perhaps burn off the
contaminant. It might take some experimenting to see how high you would have
to go in temperature to burn off the contaminant and still have the copper
usable afterwards.

I was hoping that someone had tried one of the solutions and would save my
friend some experimenting. Many thanks. I will pass the idea on to her.

Dennis in Stafford, VA
Stephen Mills wrote:

> In the past we have had problems with copper carb because the makers had
> changed their method of producing it. I'm not knowlegable about the
> process used but it seemed to coat the powder with a substance that
> resisted water and made its combining with glaze a near impossibility.
> The cure was apparently a very small amount of washing up liquid in the
> mix which de-greased the copper and allowed it to combine.
> In message , Dennis Davis writes
> >----------------------------Original message----------------------------
> >A friend is having a problem with the copper carbonate in an Oribe
> >green glaze. The copper carbonate seems to not disperse evenly
> >throughout the glaze. The glaze comes out a dark (blackish) looking
> >green than previously fired batches. Also, there are dark greenish
> >specks in the glaze. One suspicion is that the copper carbonate is not
> >as finely ground as it once was. We plan to check with the supplier but
> >are wondering whether anyone else has had this problem?
> >
> >Dennis in Stafford, VA
> >
> --
> Steve Mills
> Bath
> UK
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