I have a flagstone floor in an Atrium. When I recently purchased the house I could see that the stone was not protected. It was dirty and stained. The stone stayed wet and water puddled on the surface. I cleaned the surface completely. I completed a lot of internet research and this product was listed by many as the best. I was easy to apply. The surface was not darkened or stained by the product. It has not rained recently but after a couple days, I tested the product by spraying some water. It worked great. I would recommend this to anyone who has flagstone or similar surfaces that need protecting.