Components of Earthenware

Ancient societies crafted water-carrying vessels from earthenware.

Earthenware is the world's oldest form of pottery, dating back at least 10,000 years to the Jomon period in Japan. While many years have passed, the composition of earthenware remains much the same as in ancient times. Earthenware continues to be a popular material today for crafting dinnerware, cookware, vases and figurines.

Composition

While no precise formula exists for earthenware, typical earthenware is composed of roughly 25 percent ball clay, 28 percent kaolin, 32 percent quartz and 15 percent feldspar. Earthenware clay appears white, beige or red prior to its first or biscuit firing. When fired, white earthenware looks somewhat chalky and offers a great canvas for decorative painting. Unglazed red earthenware is often observed in the form of terra-cotta planters and pots in the garden.

Porosity

Porosity is perhaps the most defining characteristic of earthenware; the term "earthenware" typically refers to clay pottery with a 5 percent porosity or higher. Potters fire earthenware at lower temperatures than other ceramic wares, since higher temperatures will cause the earthenware to expand, thus becoming even more porous. To make earthenware less porous and more water-tight, potters frequently coat the pottery with a tin-oxide glaze. This glaze also imbues earthenware with an opaque white surface, optimum for paint decoration.

Types

Delftware is one of the most recognizable styles of earthenware. Crafted initially in Holland's Delft region during the 16th and 17th centuries, the blue-and-white, tin-glazed earthenware took inspiration from Chinese porcelain. Italy's Majolica pottery represents another well-known type of tin-glazed earthenware. First manufactured on the Spanish island of Majorca, Italy imported the colorful, intricately-patterned pottery and its potters during the 15th century.

Colonial American potters widely produced redware. Due to the clay's high iron content, the earthenware turns red, orange or brown upon firing. Unglazed redware also goes by terra-cotta, and is the most common, inexpensive earthenware available today.

Use and Care

Many dinnerware lines feature glazed earthenware plates, bowls and mugs. While earthenware's porosity often limits the potential cooking uses, it also serves as an advantage for oven and microwave cooking: earthenware casseroles and bakers better retain moisture and heat in long cooking to produce tender, flavorful dishes.

To clean glazed earthenware, wash in warm, soapy water and avoid scouring, which may scratch the glazed surface. Check with your earthenware's manufacturer whether their pieces are dishwasher-safe. Unglazed earthenware dishes should be hand-scrubbed in warm, salty water only, since the porous material will absorb detergents to taint future dishes.

Earthenware Precautions

Earthenware dishes respond poorly to sudden or extreme temperature changes. Placing a hot earthenware dish into a sink of cool water may result in shattering. Likewise, earthenware pieces are not designed for cooking over an open flame; such exposure may cause heat fractures. Earthenware's low firing temperature prevents the pottery becoming fully vitrified. As a result, earthenware is more vulnerable to chipping than semi-vitrified stoneware and porcelain, which are denser and harder.

References

• Artistic Tile & Stone: A History of Pottery
• India-Craft: Earthenware
• "The Essential Kitchen: Basic Tools, Recipes, and Tips for a Complete Kitchen"; Christine McFadden; 2000