While porcelain had been made in France from the 17thC, it was a soft paste or pate tendre, but following the discovery of kaolin this changed to hard paste in 1769, which quickly prevailed across the continent. Hard paste, a mixture of kaolin and petunse, or china clay and china rock, fired to a temperature of in excess 1300 degrees centigrade with the glaze usually in a single firing results in a vitrified bright, glassy appearance, in which the enamels are fused into the body. Apart from a brief experiment with hard paste at Plymouth and Bristol, early English porcelain is of soft paste, although the factories experimented with different recipes, using soaprock at Worcester and the addition of animal bone at Bow. New Hall developed a hybrid hard paste body but this was greyer in comparison with the white body of both soft and pure hard paste. The first efforts were undertaken in London at Chelsea and Bow, but within a few short years the porcelains were being produced at factories across England. In cross section, the difference in the paste is apparent in what is traditionally described as an "icing sugar" appearance, whereas the soft paste shows a granular texture. The different firing temperatures and technique give a glaze which is softer and "floaty" in appearance, but sunk slightly into the surface, resulting in pieces of enormous charm and quiet beauty.
Many great continental factories were supported and even owned by royalty, easing the commercial pressures, unlike the English factories which relied on private enterprise. The history of the 18thC English factories, and indeed the 19thC, is littered with hardship and financial struggle, an ironic contrast to the sometimes vertiginous prices realised in the market for these wares today.
Bone china was the great English invention of Josiah Spode C1800. This contained a proportion of kaolin but the extra ingredient was the addition of animal bone, producing a ceramic of high translucency, whiteness and strength. Eventually all the English factories changed to the standard bone china mix which is still being made by today's famous English factories such as Royal Worcester, Coalport and Royal Crown Derby. |
