Cooking With Clay Pots – Earthenware

—–By Linda Arbuckle
Earthenware usually means a porous clay body maturing between cone 06,
cone 01 (1873°F ‐ 2152°F). Absorption varies generally between 5% ‐20%. Earthenware clay is usually not fired to vitrification (a hard, dense, glassy, non‐absorbent state‐ cf. porcelain). This means pieces with crazed glaze may seep liquids. Terra sigillata applied to the foot helps decrease absorption and reduce delayed crazing.
Low fire fluxes melt over a shorter range than high fire materials, and firing and earthenware body to near vitrification usually results in a dense, brittle body with poor thermal shock resistance and increased warping and dunting potential.
Although it is possible to fire terra cotta in a gas kiln in oxidation, this is often difficult to control. Reduced areas may be less absorbent than the rest of the body and cause problems in glazing. Most lowfire ware is fired in electric kilns.
A less dense body has better thermal shock resistance and will insulate better. Earthenware generally shrinks less than stoneware and porcelain.
At low temperatures, glaze may look superficial & generally lacks the depth and richness of high fire glazes. The trade‐offs are:
• a brighter palette and an extended range of color. Many commercial stains burn out before cone 10 or are fugitive in reduction.
Earthenware has long been a respected sculpture material, but its reputation as a pottery material has varied. Many people associate fragile, under‐fired, earthenware pottery from low‐technology cultures as earthenware, and mistakenly believe that it can’t be a durable body for tableware.