Grout

Old grout may need cleaning with a wax stripper or heavy-duty cleaner plus a grout brush. Use a bleaching cleanser on tough spots. Once the grout is as clean as you can get it, rinse it well. When it's thoroughly dry, apply a coat of masonry sealer so that it doesn't absorb dirt in the future.

For mildewed grout in tubs or showers, use a grout brush with a 1:5 solution of chlorine bleach and water. Never use bleach in combination with any ammonia-based product and be sure the area is well-ventilated. When you've finished cleaning, rinse the area well to remove all traces of bleach.

Clean colored grout with a heavy-duty cleaner and a grout brush, but don't use bleach because this may remove the color from the grout. Be sure never to use a bleaching solution on colored grout. A masonry sealer can be applied to clean, colored grout to ward off future stains.