Micro-Seal HD Silane/Siloxane Water Repellent is a solvent-free, 100% active solid, silane/ siloxane repellent for horizontal and vertical porous surfaces. Double the solids of the original Micro-Seal, the coating dries down to a non-yellowing natural finish. It protects against water intrusion, efflorescence, lime, spalling, freeze/thaw cycle damage, gas stains, oil stains, mold, mildew, and UV damage.