Sweep the surface to remove all dirt, dust and debris from the grout lines.
Wash the grout surface with a mild detergent and scrub brush. Rinse the soap off the grout and allow the grout to dry completely. Remove areas of mold and mildew with a commercial mold killer. You can use an equal mixture of chlorine bleach and water to remove mold from white grout. Chlorine bleach may discolor or lighten colored grout.
Apply an exterior-grade penetrating grout sealer with a small brush. Some sealers come with an attached brush application on top of the bottle.
Allow the grout sealer to dry in accordance with the manufacturer's instructions, generally one to two hours. Apply a second coat of grout sealer and allow to dry.
Test the sealer by pouring water on the grout. If the water beads up on the surface, the sealing is complete. If the water spreads, dry the area and apply another coat of grout sealer.
Things You Will Need
- Scrub brush
- Mold killer
- Chlorine bleach
- Exterior-grade penetrating grout sealer
- Small brush or applicator bottle
- Clean and reseal grout every one to two years to maintain a protective coating.
- Apply penetrating sealer to unglazed tiles as well as grout to protect them from stains and mold growth.