If your tile grout is dirty and stained but still sound, consider whitening the grimy grout with colorant. It’s an easy, inexpensive four-step process with a DAP Kwik Seal Grout Recolor Kit. The kit contains everything you need and covers about 100 sq. ft. of 4-in. tile (smaller tile will have more grout lines and require more material).
1. Sponge on the pre-treat solution and let it sit for five minutes. Then scrub the grout with the supplied brush. Wipe clean with the chamois.
2. Apply colorant. Squirt a thin bead of the Color+Seal coating on the grout lines in a 2-sq.-ft. section. Then scrub the colorant with the grout brush included in the kit.
3. Remove excess colorant. Wipe the excess colorant from the tile using the chamois. Wipe only the tile, not the grout lines. Let dry for 30 minutes.
4. Buff to remove haze. Apply a light mist of glass cleaner and buff the tile with a clean rag or chamois. Let dry for a full 24 hours before exposing it to water.