The difference between china porcelain and bone china
Author: Source: Date: 2016-08-16 14:23:00
If you’re purchasing dinnerware for the first time or you’re due for an upgrade, it’s helpful to know the meaning behind some basic terms—including china, porcelain, and bone china—to ensure you get quality materials. British and American standards for some of these materials vary slightly, which can be confusing if you’re unfamiliar with ceramics terminology.
China, the material, takes its name from China, the birthplace of porcelain making, and is an umbrella term defined as “any glazed or unglazed vitreous ceramic dinnerware used for nontechnical purposes.” (“Vitreous” means the product is glassy and brittle with little ability to absorb water, like dinnerware, toilets, and sinks.)
Porcelain, a type of china, is primarily made with a combination of clay, feldspar, and quartz, and heated in kilns at very high temperatures. It is generally heavier and harder than bone china, with a brittle composition that can be more prone to chipping.
Bone china is made with the same ceramic materials as porcelain, but with the addition of calcified bone (up to 50 percent) and fired at a lower temperature. Calcified bone, or bone ash, is derived from animal bone and adds a creamy color and translucency to dinnerware that’s missing from porcelain. Bone ash softens the composition of china, making it less brittle and less prone to chipping compared with regular porcelain (however, the glaze on bone china is usually softer and not as strong as that on porcelain). Even though bone china is thinner and lighter and appears more delicate than porcelain, it is surprisingly durable.
In general, higher-quality bone china will have a higher percentage of bone ash. However, buyer beware: In the US, the American Society for Testing and Materials allows use of the term “bone china” for china with a bone ash content as low as 25 percent. You won’t know what percentage content you’re paying for unless you contact the producer or manufacturer directly. If a manufacturer is unable to tell you the exact percentage of bone ash in its bone china, you’re probably better off avoiding that manufacturer’s bone china.
“Fine china” has a somewhat ambiguous meaning, but generally includes any porcelain or bone china made from higher-quality clays. An article in the Journal of The American Ceramic Society defines such clays used in whiteware production as “raw materials that provide plasticity and green strength [the strength of unfired clay] during the forming stages of porcelain production and that contribute substantially to the color of the fired ware.”