You need porcelain tile grout to make your floors professional, but after installation, you may notice a haze from the grout that seems impossible to remove. There is a simple solution to the problem. Add a cup of white vinegar to very hot water, and saturate a heavy sponge with the solution. Rub hard and the haze will come right off. Be sure to rinse out the sponge often as you move to different areas to prevent putting the haze back on the floor. If you find an extremely stubborn area, pour some white vinegar directly to that spot and rub away with the sponge.