Source International – Manufacturing Materials – Learning Center
Bone China is a kind of porcelain composed of Bone Ash, Kaolin, and Feldspathic material. Part of its name comes from the fact it, by definition, contains a minimum of 30% phosphate derived from animal bone and calculated calcium phosphate. Known for its very high degrees of translucency and whiteness, as well as superior chip resistance, Bone China is produced in thinner cross-sections than other types of porcelain due to the overall strength of the material.
The production of Bone China is very similar to standard porcelain, however a bit more attention is needed during production due to a narrower vitrification range and overall lower plasticity. The standard formulation is approximately 25% Cornish stone, 25% Kaolin, and 50% Bone Ash. The bone in its name is derived from the Bone Ash which is used in its formulation. Bone Ash is produced from cattle bones with lower iron content. The cattle bones are crushed, de-gelatinized, and then calcined at temperatures up to 1250 C. The resulting ash is then milled to the specified particle size. As the separate components which go into Bone China are expensive and production more labor intensive, the material still enjoys a luxury status and higher pricing to this day.
Originally exclusively produced in England, this elegant material has seen its production expand considerably in recent years. China is now the largest producer of Bone China in the world. Other countries which are producing this material include Bangladesh, India, Indonesia, Sri Lanka, and Thailand.