One of the most important steps when laying tile and spreading grout is to clean the wet grout from the surface of the tile before it dries. If you don't do this, the grout residue will dry on the surface of the tile to create grout haze. This haze will mar the appearance of the tile and make it look dirty. However, there are ways you can clean the tile to remove the grout haze.
Mix 1 gallon warm water with 1 cup sugar. The sugar will accelerate the solution's ability to dissolve the grout haze and residue.
Spread a thick layer of the sugar water over the surface of the tile with a sponge.
Let the sugar water set for at least two hours.
Scrub the dried grout film off with a plastic scrubbing pad. Work in a circular motion until the water gets cloudy and the grout residue dissolves completely.
Rinse the area with clear water and dry it completely with a clean cloth.