Bone china

Staffordshire Bone China chocolate cup with lid, enameled gold decor, approx. 1815-20 ( Victoria and Albert Museum )

Bone china (Engl. Bone China ) is a soft-paste porcelain with very high resistance to chipping. Very white and translucent, it is considered the best and finest porcelain .

Specification according to the classification of ceramic bodies

Class: sintered products

Subclass: porcelain

Group: soft-paste porcelain

Subgroup: Bone porcelain (bone china) and fine bone china (Fine Bone China)

The starting point for the development of bone china was frit china , known as "soft paste". Components of the frit were replaced with other admixtures, including bone ash . In addition to kaolin , feldspar and quartz sand , bone china now contains up to 50 percent burned bone ash, the high proportion of calcium oxide and calcium phosphate which gives the porcelain its special transparency.

In 1748 Thomas Frye , artistic and technical director of the Bow porcelain factory (East London, Stratford le Bow), applied for a corresponding patent. Josiah Spode developed the process further into fine bone china in his factory in Stoke-on-Trent between 1789 and 1793 .

The firing sequence is also a special feature of bone china. For example, the temperature of the biscuit firing is 1280 ° C higher than that of the subsequent glaze or smooth firing of 1080 ° C.

literature

• Felix Singer, Sonja S. Singer, Industrial Ceramics - Masses, Glazes , Color Body Manufacturing Processes , Volume 2, ISBN 3642929893 , S.78 (partial view)
• William Evans, Art and History of the Potting Business , 1846, 7