This Smartseal Natural Stone 'Dry Finish' Sealer is an effective impregnating sealer which can be used on a range of hard surfaces, including but not limited to sandstone, granite, limestone, Indian sandstone and slate. The product leaves a totally dry finish which is touch dry in 2 - 3 hours, and waterproof in 24 hours. The chemical structure is altered of the porous stone which will provide not only a superb water repellence but also a stain-resistant surface. You can expect a lifespan of up to 5 years with this product which will protect you against a range of green growth like moss, algae and lichen spores.