Porcelain can be given a smooth, honed or matte finish as well. This is done either at the time of manufacturing in the mold or after firing by grinding down the surface of the tile to a smooth finish. Matte finish tiles that are not ground down are identical to textured porcelain tiles in water resistance and stain resistance. They differ only in style, look and feel. Matte finish tiles that are ground down after firing may contain microscopic pin holes or pores only in the surface. These pores make the tile likely to collect surface dirt and require deeper cleaning. To prevent this, apply an impregnating sealer to the tiles prior to grouting and on a yearly basis.