Bone china is a very white, translucent and strong type of porcelain made with a large proportion of bone ash, traditionally around half the recipe. It is almost always slip cast and fired on specialist schedules.
What Is Bone China?
Bone china was developed in England in the eighteenth century and became the classic material for fine tea sets. The bone ash, calcium phosphate from calcined animal bone or a synthetic equivalent, acts as a flux and gives the fired body its whiteness and glow. Digitalfire gives a traditional recipe of about 50% bone ash with kaolin and Cornish stone.
It is famously short, meaning it has very little plasticity, so it is rarely thrown. Studio potters who use it usually buy a ready-made bone china casting slip and pour it into plaster moulds, then thin the walls to bring out the translucency.
Commercially, bone china is often bisque fired high and glaze fired lower, the reverse of typical studio practice, and it has a short firing range, so it can slump if overfired. That makes it a material for experienced potters or slip-casting courses rather than a first clay.
This pottery glossary entry from Le Studio Art Space is general educational content. Always follow the clay, glaze and kiln makers’ data for your own materials and equipment.