Years of grease buildup and foot traffic can mask the current condition of the grout lines. After we clean your tile, cracks, missing grout or staining in the grout lines may now be more apparent. Most stains in grout are permanent and we recommend sealing your grout lines to prevent future staining (especially after it is first installed). Our cleaning process does not damage grout or tile. We cannot guarantee that all stains will come out of grout, as grout lines act like a sponge and can absorb many liquids, leading to permanent staining. Epoxy grout does not absorb liquids.