Porcelain, also known as ceramic, is a good choice for flooring and wall tiles thanks to properties such as low permeability and elasticity, considerable strength, toughness and resonance, as well as a high resistance to chemicals and thermal shock. It is very stain resistant, has a very low water absorption rate and so can be used for interior and exterior applications. For centuries, porcelain tiles have long been valued for their beauty and durability. Unglazed porcelain tiles are usually polished to a high gloss shine but because they are not coated with a glaze, such tiles benefit from the application of a penetrating sealer to give it added stain resistance and to aid cleaning.