The grooves between all external and internal ceramic surfaces to be grouted must be sound and thoroughly cleaned before the application of the product. All traces of oil or grease must be removed. All loose particles of mortar or tile adhesive in the groove must be removed. Joints should be emptied to at least 2/3 of the tile thickness. Before grouting make sure that tiles are set and that the adhesive had completely dried. Joints width should be from 1.5 mm to 20 mm.