Ash glazes are made from the ash of various kinds of wood or straw.
Porcelain is the non porous option of ceramic. It is usually translucent, lighter in weight and thinner and has a delicate appearance. It has an incredible durability.
Dehua Cherry-blossom-patterned Teapot with an Ash Glaze
Often made into finer items, porcelain can have many other materials mixed in with the kaolin clay - like silica, feldspar, quartz, glass, bone ash, and/or alabaster. These ingredients help to fortify the clay mixture and when fired produce a strong product which shares some qualities with enamel.