Bone Ash (TriCalcium Phosphate) is source of calcium and phosphate traditionally used in bone china for translucency and lowering the maturing temperature. The calcium acts as a flux, while the phosphorous acts as a glass former. When added to a clay body such as bone china, bone ash lowers the maturing temperature and adds translucency.
Bone ash may also be used to give texture in low fire glazes. In low-fire glazes, bone ash acts as an opacifier, while in high-fire glazes it can create translucence. You may find that it is rarely used in glaze recipes; this may be because bone ash can have a tendency to cause the glaze matrix to thicken, or materials within it to flocculate, or clump together. If you mix a glaze containing bone ash, it is recommended that you use a little bit of deflocculant such as Darvan 7.
Bone Ash (TriCalcium Phosphate) is source of calcium and phosphate traditionally used in bone china for translucency and lowering the maturing temperature. The calcium acts as a flux, while the phosphorous acts as a glass former. When added to a clay body such as bone china, bone ash lowers the maturing temperature and adds translucency.
Bone ash may also be used to give texture in low fire glazes. In low-fire glazes, bone ash acts as an opacifier, while in high-fire glazes it can create translucence. You may find that it is rarely used in glaze recipes; this may be because bone ash can have a tendency to cause the glaze matrix to thicken, or materials within it to flocculate, or clump together. If you mix a glaze containing bone ash, it is recommended that you use a little bit of deflocculant such as Darvan 7.