Will caulk adhere to the shiny & smooth surface of the tiles? If not, you could make a fixture with 60 grit sandpaper that roughens the surface within 3/16" of the edge. 100 (sand grains to the inch) is probably too fine, it'll clog the paper quickly.
Last edited by Wuzzat?; 02-27-2014 at 04:36 PM.