Tom Wirt on fri 10 apr 98
Lately we've been getting occasional but freqwuent enough to be painful
spots showing up in/under the glaze after final firing. (We're Cone 10,
white stoneware which is primarily AP Green fireclay with grog - and the
usual extra stuff including some Kyanite.)
The burns are like small pimples (sorry to be gross) sometimes just
color, sometimes an actual pinprick crater, Color is greenish black,
somewhat metallic. Last time it happened the clay company blamed it,
what else, on AP Green. But looking at the spot I suspect copper
contamination, and I don't think that would appear in Missouri???
Also reading articles in CM, various book and reviewing the pop out
discussion a year ago December, my suspicions lie more with the grog.
Any ideas, suggestions before I really go sit down with them about
this?
TIA for any help.
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