Porcelain

Porcelain is a vitrified, non-porous ceramic obtained by mixing a white clay called kaolin with feldspar and quartz and firing it at very high temperature. It holds a distinct place in the pipe world: for roughly two centuries it was one of Central Europe's most familiar bowl materials, and over the same span it was also the material most criticized for its smoking quality.

This entry covers the material itself; for the pipe type made from it, see the porcelain pipe entry.

Composition and Firing

The composition of European hard-paste porcelain was cracked in Saxony in 1708, following Johann Friedrich Böttger's work built on Ehrenfried Walther von Tschirnhaus's long experiments; the royal manufactory was founded at Meissen in 1710. The earliest recipes included gypsum as a flux alongside kaolin. Records indicate this was replaced first by limestone in 1719, and around 1730 by a local rock rich in potassium feldspar; this settled the kaolin-feldspar-quartz composition regarded as classic today.

The mixture is generally fired between 1300 and 1400 degrees. At this temperature the feldspar melts and fills the spaces between clay particles; on cooling, a glass-dense body with sealed pores results. Vitrification gives porcelain three distinct properties: water-tightness, translucency in thin sections, and a mechanical strength high for a ceramic. The same properties make porcelain excellent for tableware and ornamental objects, and problematic for a pipe bowl.