Window molding pores that trap moisture and debris, such as soap scum and cleaner residue. Over time, the contaminants stain grout, often changing grout from bright white dull yellow. The glass block grout s coarse surface carries holes in cleaning cloths or sponges, leaving small particles on the grout surface. Some glass block applications use a silicone sealant as a sealant instead of grout. Replacing a glass block window grout with silicone seal gives the joints a smooth texture that repels contaminants.
Place a cloth on the floor under the window molding. Cover the walls surrounding the window with plastic foil, using masking tape to hold the plastic against the wall. Cut a notch along the center of each glass block grout joint with hand-held grout saw. Run the grout saw over each horizontal and vertical grout joint until the saw handle reaches the joint. A hand-held grout saw blade uses a cemented carbide tip to grind through the grout surface.
Rate the edge of each grout joint where grout touches window molding with a carpet knife, using the knife blade to create a ¼ inch deep groove in grout along each edge of each glass block. Hold a cold chisel blade on the grout’s ¼-inch deep ridge and angle the chisel toward the groove cut in the center of the grout joint. Tap the chisel handle with a hammer until grout at the end of the chisel releases from the joint. Be careful to keep the chisel outside the glass block. Remove all grout using this method.