How To: Seal Grout
Make it easier to keep your bathroom sparkling by following these simple steps to seal your grout.
Even if you keep your bathroom tiles clean, dirty grout lines can really detract from the look of your tiled floors and walls. Because cement-based grout, whether sanded or not, is porous by nature, substances like oil, grease, and water tend to seep inside and cause ugly discoloration. The best way to prevent this is to seal your new grout and repeat as needed—every year or so for wall and floor tiles that don’t get much moisture, and more often for grout in the shower or on the bathroom backsplash. Adhere to the following instructions, though, and you’ll learn how to seal grout and create a reliable barrier against unsightly stains and a dingy appearance. You may never have to scrub those grout lines again!
STEP 1: Clean and repair grout.
Before applying a sealer, be sure to clean your grout thoroughly and repair any cracks or crumbles in the grout lines. Otherwise, you’ll seal in dirt and damaged seams. Scrub away as much of the grime as possible using a toothbrush dipped in soapy water. (Switch to a 50-50 vinegar and warm water solution if you’re trying to eradicate stains.) Tackle one grout line at a time. When you’re finished cleaning the grout, allow the area to dry for 45 minutes before sealing.
STEP 2: Choose your sealer.
Next, choose your sealer based on the type of tile you have and its location. No one sealer is best suited for all situations. As you’ll see when you get to your home improvement store, the variety of products available allows for a certain level of customization. Labels specify which sealers work best with marble, stone, and ceramic tiles, as well as how much moisture the sealer can tolerate, be it high moisture in the shower or low moisture along a kitchen backsplash.
Depending on your tile and its location, you can narrow down the choices to two main categories: penetrating sealers and membrane-forming sealers.
- Penetrating sealers use a water or mineral spirit base that lets the formula’s tiny particles of latex or silicone penetrate the granular structure of the grout. As the porous grout absorbs the sealer, the particles of latex and silicone fill in all the gaps, keeping moisture out. These sealers are the best choice for use in especially damp areas, such as bathrooms and, in particular, showers.
- Membrane-forming sealers create a coating on the surface of the grout that resists water permeation. (These sealers work well in the kitchen but should not be used in the bathroom; membrane-forming sealers won’t allow water that’s trapped underneath the tile to evaporate, which, in a swampy shower, could lead to mildew.) These sealers also often feature pigments, so you can change the grout color. While membrane-forming sealers are good for unglazed tile like stone, they won’t adhere to glazed tiles, such as most ceramics.
STEP 3: Choose your sealer applicator.
Choose the applicator tool that’s right for you. Although aerosol spray-on sealers are commonly used for reasons of convenience, there are a few cases in which they may not be the best choice for your project:
- If you have very thin grout lines and unsealed tiles, a sponge allows you to seal larger sections of your bathroom (walls or floors) easily by wiping over both surfaces at once.
- For glazed tiles where sealer won’t adhere, you’ll need to seal only the grout lines using an applicator brush or specialty applicator bottle with a rolling wheel on top.
Whichever tool you choose, read the manufacturer’s directions on how to seal grout before you begin.
STEP 4: Apply sealer slowly and deliberately.
Apply sealer in small areas at a time, working left to right. By working methodically, your grout lines will look more consistent and your sealer will provide better protection—no spots will be overlooked! Keep a dry cloth close by to wipe off the excess sealer. Whether you’re sponging over a large area or using an applicator to avoid drips on glazed tile, you’ll want to remove sealer from the tile before it starts to dry (within five to seven minutes of application) so that you’re not left with a foggy film that’s nearly impossible to remove.
STEP 5: Apply a second coat of sealer.
Once you’re done with the first coat, let it dry for an hour before applying a second. (Generally speaking, it takes one to three coats of sealer to achieve adequate protection.)
After the second coat dries, test the surface with a few drops of water. The liquid should bead up into droplets; if not, apply a third coat to ensure quality results.
Finally, let your tiled space dry completely. Some sealers need only 24 hours to cure, while others can take up to 48 hours; check the manufacturer’s directions on how to seal grout to be certain. While it may be inconvenient to keep a room off-limits for a day or two, remind yourself how convenient it will be the next time you clean your grout. A good sealer means less time scrubbing, so this is one chore that will make your routine bathroom cleaning a breeze.