These are porcelains are made using Grolleg kaolin. P700 (Plainsman) has 19% G200 Feldspar and Coleman (popular among potters in the US) has 31% (P700 switches the 12% to kaolin). Although the Coleman porcelain is more vitreous (top right) it is not more translucent. But it is a lot more problematic in fired warping and plucking (lower left). Grolleg kaolin has a high natural flux content so less feldspar is needed than in recipes calling for American kaolins. And that extra kaolin in P700 gives us something: More plasticity. Another thing: These are not as translucent as what can be achieved at middle temperature oxidation.
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