Glazed tiles are by nature ones that have already been effectively sealed with a very thin layer of glass. Now the dullness may be a result of wear and tear and may tell you that the tiles are nearing the end of their useful life. However, in most cases the dullness indicates there is a build up of deposits on the surface. Now, if this is limescale, we’d recommend you use a product like Shower Tiles Plus. If you have dull glazed floor tiles then we’d recommend you use something like Heavy Duty Tile and Grout Cleaner but make sure that you rinse the floor really well afterwards.Copyright Ian Taylor and The Tile and Stone Blog.co.uk, 2013. See copyright notice above.