After installing new tiles in their bathroom, people often say something to themselves along the lines of “I used enhanced grout with additives to reduce mildew - do I really need to seal the grout as well?” The simple answer is yes, you should. Sealing new grout will help prevent dirt from working it’s way into the grout line and even if your grout contains additives to fight mildew, a sealer will provide added protection against the formation of mold and mildew. Plus, sealing the grout will actually extend its life, and since sealing new grout is a quick and easy job, so why not do it?
Penetrating sealers have a mineral spirit or water base with tiny particles of latex or silicone in suspension designed to penetrate the granular structure of the grout. The liquid is absorbed into the porous surface and after the base evaporates, the water resisting particles of latex and silicon remain in the grout, filling up tiny holes and keeping moisture out. Only penetrating sealers should be used in baths and showers.
Membrane Forming Sealers
As the name implies, membrane forming sealers create a membrane or coating on the surface of the grout. Although designed to help prevent water penetration, they often contain pigments that allow you to change the color of existing grout. Membrane forming sealers are best used on floors for several reasons.
Most baths and showers use glazed tiles, while floor tiles are often unglazed and a membrane forming sealer doesn’t adhere well to glazed tiles. In high moisture areas, membrane forming sealers won’t totally prevent water from getting in under grout and tiles. Once the moisture has soaked in, the sealer will actually prevent it from evaporating and, moisture trapped under the sealer will promote the formation of mold and mildew.
Applying Grout Sealer
All sealer manufacturers recommend you allow new grout time to dry; most recommend 24 to 48 hours at a minimum. Since all sealer products are slightly different be sure to read and follow the directions on the product you choose. In general, the process is to apply 1 to 3 coats of sealer, after applying the first coat, wait about an hour and reapply. Wait another hour and repeat.
Apply your sealer using a small paintbrush or a sealer applicator bottle that has an applicator wheel on top you simply roll along the grout line. Be sure and keep a cloth close by to wipe off any sealer that might get onto your tiles, before it can dry. Sealer left on tiles will dry with a haze that is virtually impossible to remove.
After the sealer has had a chance to set, check to see that it’s working by putting some small water drops on the grout line. The water should bead. Over time, grout sealer will lose its effectiveness. Keep your grout looking clean and mildew free by applying new sealer every two or three years.