I have just layed a path using indian sandstone flags and am considering the use of a patio sealer to protect the flags. The container suggested that certain flags may become slippery when wet if the sealer does not penetrate the surface. I would have thought that sandstone was fairly porous. Any thoughts ?
Sandstone is relatively porous, but the degree of porosity varies between the various types of flags that are available.
I'd suggest testing out this unnamed sealant on a spare flag or an offcut and seeing what the results look like before committing it to the rest of the paving.