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Alternate Names: Porcelain stone, petuntse
A low-iron, high quality material found in China. It forms the basis of a historic porcelain industry. The material has a chemistry similar to Cornwall Stone (15% Al2O3, 75% SiO2 + a mixture of CaO, MgO, K2O, Na2O), it can be mixed with kaolin to produce a fine porcelain. A large percentage of Petuntse is required in recipes to produce a vitreous fired product. That means the remaining kaolin assumes the burden of all of the plasticity exhibited by the pugged material, thus bodies are very non-plastic (compared to western tastes).
We have attempted to communicate with exporters in China but strangely, they are unable to describe the properties that relate to its use in porcelains. All we were able to get from one supplier was the chemistry (shown here). The chemistry from another supplier was similar (except for a higher LOI, lower SiO2). We have not been able to get samples due to the unreasonably high cost. If you have a sample and would like to have it tested with different North American or European kaolins (or New Zealand Halloysite), please arrange to send it to us. We can do the SHAB test on it at a range of temperatures and evaluate its response to white plasticizers. And we can do fit-testing of common glazes with the porcelain it produces. This will yield a starting recipe with suggested adjustments for plasticity, whiteness, translucency, degree of vitrification, firing range, etc.
Haicheng Bright Future Mineral claims their material contains lithium also, imparting "strong melting ability", and that it also has good plasticity because of "large amount of sericite mineral content". They also say: "Lithium porcelain stone is widely used in daily porcelain, building porcelain, sanitary porcelain, high white porcelain brick, especially ceramic glaze and frit".
Petuntse at Wikipedia
Also know as "porcelain stone", in China this is mixed with kaolin to produce porcelain, "Jingdezhen ware" being the most well known.
Jingdezhen Porcelain at Wikipedia
Porcelain made in China using the petuntse (porcelain stone) material.