Grout that is missing, cracked or discolored can make tiles on countertops or backsplashes appear old and dingy. Missing grout between tiles can also cause water damage to the substrate of a countertop. Replacing tile grout can be an inexpensive and simple do-it-yourself project if you have the right tools and materials. Even if large amounts of tile grout need to be replaced, you can easily repair grungy-looking tiles.
Use a sponge to apply the vinegar and water solution to the area of tile grout that needs repairing. This will clean mildew from tiles and grout. Use the grout saw on the grout lines between tiles to remove cracked or discolored grout. Wear safety glasses while using the grout saw.
Take the sponge, rinse it and wet it with clean water. Pass it over the grout lines. Remove excess water and dry with the paper towels.
Buy a premixed grout that matches the color of your tile grout. You should also get the correct type of grout, which is dependent on the grout joint width. Sanded grout is for tile joints that measure greater than 1/8 of an inch, while unsanded grout is best for joint widths that are 1/8 of an inch or smaller. You can get premixed grout in any hardware or home improvement store.
Replace tile grout by spreading the premixed grout with the float over the tile surface. Be sure to place the float flat against the tile surface and press to fill the joints. Then go over it again with the float at a 45-degree angle and pass it diagonally over the tile surface.
Clean the tile area with a damp grout sponge. If necessary, repeat the process with a rinsed sponge. Allow the grout to set up for approximately 15 minutes, then wipe with a rag to remove any remaining grout film on the tiles.
Let the grout dry according to manufacturer's instructions. It can take 24 hours or more for grout to dry. Apply grout sealant after the grout dries completely.
Wait until the grout sealant is dry. You will notice a cloudy film on the tiles when this occurs. Polish the tiles with a towel.