Concrete & Stone - Cleaning & Sealing
I recently visited the missions of San Antonio. The walls are made of limestone and concrete. If you look at the limestone you'll see that nature has literally melted inches off the surface.
There are two forces of nature working against the stone. One, is freeze thaw. When water saturates into the surface of the stone and freezes, the water expands.
At the same time, the stone contracts when freezing. This process slowly eats away the rock surface. Secondly, we have what's called acid rain. This means the water alone over time melts the surface.
I recommend sealing stone with solexene. This is a liquid sealer with a small molecule size.
The sealer penetrates the stone encapsulating the small granules that make up the stone. When it dries it has a natural look.
Now, the stone will not absorb moisture. The cracks will also be protected.