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.

Behavior as a Pipe Material

The one property that determines the material's behavior in a pipe is its non-porosity. Fired at a lower temperature and so retaining its pores, clay pipe paste absorbs part of the moisture released during smoking into its body; vitrified porcelain can't do this, and all the moisture stays as liquid inside the bowl. This is why a separate condensation chamber is added below the porcelain bowl; the details of this arrangement are covered in the entry noted above.

The second consequence of the vitrified body is heat behavior. Porcelain conducts heat relatively quickly, and because it retains no moisture to cool through evaporation, the bowl heats up in a short time. Third, no seasoned crust develops on a surface that doesn't absorb moisture; unlike materials such as briar and meerschaum, which "break in" over time, porcelain keeps behaving the same way it did on day one. There's an upside to this too: because the body picks up no smell or taste from the tobacco, no trace carries over between blends after cleaning.

The material lends itself well to decoration. Because paint is applied under or over the glaze and refired, colors don't fade over time; this is why porcelain bowls still look legible even two centuries later. Today porcelain is almost never used as a standalone bowl; the ceramic appears more often in the linings some manufacturers fit inside briar bowls and in hookah bowls. For a comparison with other options, see the pipe bowl materials entry.