This word is derived from a process "vitrification". Vitrification is a partial fusion of the clay body to achieve low porosity & impermeability to water. Vitrification is achieved by heating the raw body of tile up to 1200º C to liquidize it. So vitrification is a term for the process of making a tile body. With the vitrification process, 5 types of tiles are available in the market today... Soluble salt tiles double charge tiles full body tiles digital GVT color-body digital GVT