Glossary
The words of the craft, in plain English.
- Anorthite
- A calcium aluminosilicate crystal formed in bone china during firing.
- Backstamp
- The maker’s mark printed or impressed on the base of a piece; a declaration by the maker, not a test result.
- Biscuit (bisque) firing
- The first firing, before glazing. For bone china it is the hottest firing.
- Bone ash
- Calcined animal bone, ground to a powder; principally calcium phosphate.
- Bottle kiln
- The traditional brick kiln of the Potteries, named for its shape.
- Burnished gold
- Gold decoration polished by hand after firing to a soft lustre.
- Calcium phosphate
- The mineral that gives bone china its name and much of its character; from bone ash or other sources.
- China clay (kaolin)
- A pure white clay that gives the body plasticity.
- China stone
- A feldspathic rock that melts in the kiln to form glass.
- Crazing
- A network of fine cracks in a glaze.
- Fettling
- Trimming seams and edges from shaped ware before firing.
- Glost firing
- The firing that melts the glaze.
- Hard-paste porcelain
- Porcelain of kaolin, feldspar and quartz fired at a very high temperature, as first made in China.
- In-glaze decoration
- Decoration fired so that it sinks into the glaze.
- Jiggering and jollying
- Shaping flatware on, or hollowware in, a spinning plaster mould with a profile tool.
- New bone china
- A trade name for bodies resembling bone china with little or no calcium phosphate; not, as far as we have found, a category defined in the standards.
- On-glaze decoration
- Decoration fired onto the surface of the glaze.
- Saggar
- A fireclay box that held ware in a bottle kiln.
- Setter
- A shaped support that holds a piece during firing to prevent distortion.
- Slip casting
- Shaping by pouring liquid clay into a plaster mould.
- Soft-paste porcelain
- Eighteenth-century European porcelain bodies made without true kaolin-feldspar recipes.
- Translucency
- The passage of diffused light through a material.
- Tricalcium orthophosphate
- Ca₃(PO₄)₂. ISO 5644 defines bone china as containing at least 35% of it by mass of the fired body.
- Vitrification
- Fusion of a ceramic body into a dense, glass-bonded, non-absorbent material.