Dannon Rhudy on mon 24 jul 00
... knew a guy who used a very high Nepheline Syenite copper red
>glaze and he insisted on using pure carbon for early reduction. His copper
>red would trap so much carbon that he had areas that were very black and he
>refused to lighten up on reduction. So this led me to think that one could
>trap carbon with a glaze containing just Neph Sy.....
Craig, I have noted that a high-neph sy red glaze that I
have is VERY sensitive to carbon trapping - to the point
that too much reduction will cause the breaking areas that
usually go white over porcelain to go grey to dark grey,
instead. Further, that same glaze over shino will turn
charcoal to black in early heavy reduction - most interesting.
regards
Dannon Rhudy
and no soda ash. Ian
>Currie says that he sees this happen a lot in high flux mixes in his 35
>glaze biaxial grid tests. I say some carbon trap in the .6 limestone
>biaxial of Ian's that I did here and the trapping occured in the higher
>flux areas. Sorry for the long winded account.
>
>>Any experience of sulphur in relation to this problem?
>
>Absolutely zip!! I fire with propane and my clay is porcelain so I don't
>have any experience with sulphur at all. Perhaps someone on the list that
>does know about this will comment. If not, I can talk to some folks here
>that oil fire and see what gives.
>
>later, Craig Martell in Oregon
>
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