Porcelain stoneware is a very hard material with particularly high resistance to chemicals. It is also frostproof and waterproof. It is the ideal floor material for restaurants, airports, schools, hospitals and shopping centers and is also widely used in homes. Porcelain stoneware may undergo an industrial polishing process. This produces the “polished” type, which has a mirror finish, but unlike the “natural” (i.e. unpolished) material, it does present some stainability problems. The polishing process opens the pores of the porcelain stoneware, making it easier for dirt to penetrate. Protective treatment of porcelain stoneware is intended not to protect it against wear (unnecessary, in view of its hardness) but to create a barrier against dirt and stains, and simplify routine care procedures. It is important to distinguish between protection for “polished” and for “natural” material.