Most Porcelain tiles don't have any glaze, most are Matt finish, however a few do have a glaze. The coloration layout is baked into the tile, meaning the colour coloration runs through the tile, these are known as thru-frame Porcelain tiles, therefore in addition to them being very tough wearing, any chips or wear on the tile might be hard to see. Fixing Porcelain takes extra time because of the density, weight and frequently huge size of these tiles in comparison to Ceramic tiles.