How to Seal Grout and Keep Grime Out

Before you can start the actual tile grout sealing process, you’ll need to make sure the grout is clean and intact. You can repair loose grout by removing it and applying a fresh layer of new grout.

If your grout is still in good shape but looking a little dull and dingy, be sure to clean your grout first so you’re starting with a fresh slate. You can use an old toothbrush with commercial grout cleaner, or you can sub this out for dish soap, baking soda with or without vinegar, lemon juice with cream of tartar, or even shaving cream. It’s always best to spot-test any cleaner first, though.

To remove excessive amounts of grime, carefully use a razor blade to lift any gunk out.

Picking the right grout sealer can be just as important as picking the right grout itself. It has the power to make your grout shine and your tiles pop or to muddy the whole picture. Depending on whether you have stone, marble, or ceramic tile, you’ll find a variety of different sealers that you can use for each.

Along with the material, you’ll need to take the level of moisture your tile will be exposed to into account. Based on that, there are two types of sealers: Penetrating and membrane-forming grout sealers. Penetrating sealers are designed for maximum water protection, soaking in and sealing the pores in the grout. It is the more durable of the two, protecting from water, mildew, stains, and more. Penetrating sealers are best used in areas exposed to a lot of water, like showers or bathrooms. 

Membrane-forming, or non-penetrative, grout sealers are designed to be more aesthetically pleasing, only covering the surface of the grout and giving it a shiny coat. However, while it still has some protective power, it is overall less protective and durable to a penetrative sealer. It is easy to peel off and it's easier for water to get trapped underneath, which can cause mildew growth due to a lack of evaporation. It's best used in kitchens and backsplashes, but should be avoided in areas that are consistently damp.

Most grout sealers are in the form of an aerosol spray, but this isn’t always the most practical solution for sealing grout. For example, you may have glazed tiles that the spray won’t easily adhere to, so you’ll need an applicator brush or a grout sealer roll-on applicator bottle. If you have thin grout lines around unsealed tiles, opt for a sponge to cover large sections at once.

Working from left to right, begin applying grout sealer to your grout in small sections. Maintain close attention to every detail, taking care to cover the entire surface of the grout evenly. Use a dry cloth to wipe off excess sealer from tiles as you go.

Wait 10 minutes for your grout sealer to settle, then use a dry cloth and wipe up the excess sealer residue from the surrounding tile. Sealer becomes difficult to remove when dry and letting it do so can leave your tile looking foggy. 

After you’ve applied the sealer to your grout, allow it to dry for one hour. Then, drip a few water droplets onto the surface and see how it sits. If it beads up and doesn’t appear to penetrate, your sealer should be good to go. If it doesn’t, then you’ll need to apply an additional coat.

If water won’t bead up on your grout, apply a second coat of sealer and wait another hour for it to completely dry. Then, do another water droplet test—if it still doesn’t bead up, you may even need to do a third coat of grout sealer for full impermeability.