General Cleaning for Flagstone Substrates Surface preparation is a critical step that ensures your coating bonds properly. We make it simple for you with these easy-to-follow instructions for general cleaning. Be sure to read them carefully before you begin, and print a copy so you have them handy throughout the preparation process. You'll need: H&C® De-Greaser, a stiff broom, a plastic sprinkling can, a garden hose with a pressure washer nozzle and household bleach. Cleaning messy grease and oil stains If grease or oil is present on your surface: Thoroughly saturate your surface with H&C® De-Greaser according to package instructions. Using a stiff brush, agitate the entire surface to make sure the H&C® De-Greaser removes all the stains. Let the solution sit for at least 10 minutes. Using a garden hose with a pressure washer nozzle, rinse the surface thoroughly with clean water so that no cleaning mixture remains. Allow the surface to dry for at least 24 hours. Before applying your coating, sweep with a stiff brush to remove any remaining residue. Removing mold or mildew If mold or mildew is present on your surface: Using a pump-up sprayer, mix 1 part bleach to 3 parts warm water. Caution: make sure to always pour the bleach into the water so the bleach doesn't splash on you.* Thoroughly and evenly saturate the surface with the solution. Scrub the mildewed areas with a stiff brush. Let the solution sit for at least 10 minutes. Using your garden hose, rinse the surface thoroughly with clean water so that no cleaning mixture remains. Allow the surface to dry for at least 24 hours. Before applying your coating, sweep with a stiff brush to remove any remaining residue. *Wear protective glasses or goggles, waterproof gloves and protective clothing. Quickly wash off any of the mixture that comes in contact with your skin. Do not add detergents or ammonia to the bleach/water solution. Choosing your coating Now you're ready to apply your coating. Here are the H&C® Coatings we recommend for your particular application. They are listed in priority order based on which products will give you the most beautiful results. Color Coatings Clear Water Repellents H&C® Silicone Acrylic Concrete Sealer H&C® HB-150/HB-100 Water Repellent H&C® Shield PlusTM Ultra Concrete Stain H&C® SB-50 Water Repellent Clear Sealers H&C® Clear 23 Sealer H&C® WB-50 Water-Based Water Repellent H&C® Chatahoochee Sealer H&C® Commercial Grade Super V Water Repellent H&C® Concrete & Masonry Waterproofing Sealer H&C® Block Shield Masonry Waterproofer