Grout Revive Samples are an excellent way to determine the perfect color for your project. Remember to use sealer remover before applying if you have previously sealed your tile or grout. Sealer remover will reopen the pores of your grout to accept the application of Grout Revive Grout Colorant. To help determine if you grout has been previously sealed you can wet the grout lines with water. If the water is NOT absorbed or beads on top of the grout line than you need to first use sealer remover to remove the seal. The grout might also darken in color when wet if it is NOT sealed.