After the drying process the clay roof tile, except it remains natural red, is either engobed or glazed.
Engobed clay roofing tiles have matt, matt-glossy or glossy surfaces. Engobes are applied as clay-containing slips by dipping, pouring over, centrifugal casting or spraying on the still unfired clay tile.
Glazed tiles are covered with a very hard continuous glass layer that closed all pores and makes the tile extremely water-resistant. at the same time this glass layer gives the tile its special shiny look.