Glazed Shower Tile Shows Darker Color Around The Tile Border Than Is Normal - ( Picture Framing ).

This is a condition known as "picture framing". There is usually a great deal of confusion about its cause. In the cases we have investigated it has been the same cause and required the same cure.

The cause is moisture that is able to enter the tile body and be trapped under a light colored glaze. The path of entry is either through unsealed grout, or it is between the edge of the tile glaze ("englobe") layer and the top of the grout joint. Less depth to the grout joint could have prevented this. Sometimes the tile manufacturer will not have the "englobe" layer wrap down the side quite far enough, or that section may be too thin and have very small holes in it.

The answer in either case is to seal the grout, after leaving the shower unused for however long it takes to dry out and the "picture framing" to disappear. In the case of the "englobe" layer use the solvent based acrylic sealer - S-B-S Sealer. Keep in mind that you are not only sealing the grout, but also sealing the edge of the tile.