Black Diamond Stoneworks Ultimate Grout Sealer - Premium Stain & Waterproof Sealant for Tile, Marble, Floors, Showers & Countertops | Long-Lasting Protection for Bathrooms, Kitchens & High-Traffic Areas

I was concerned about purchasing a sealer that would cause new black grout to become discolored after sealing it as had been my experience in the past. After doing some research, I learned that as long as the sealer is water-based this would not happen. Even so, I was still skeptical but decided to give BlackDiamond a try based upon other reviews. I applied it to the grout with a paint brush in an inconspicuous spot behind the toilet and was very pleased to find that not only did not change the color of the grout at all, but it did a fantastic job of sealing it. It's an excellent product that is worth every penny and goes a very long way.