- Sweep the flagstone's surface and then spray it with water from a garden hose, just enough to moisten the surface.
- Apply a heavy duty coating stripper to the flagstone using either a paintbrush or a paint roller. Wait 20 minutes and check the old sealer to see if it is softening. Softening may not happen for up to 2 hours. Keep checking every 20 minutes.
- Scrub the old sealer off with a deck brush. Get inside all the grout lines and stone crevices. Once the old finish is scrubbed off, rinse the flagstone with clean water.
- Vacuum up any standing water with a Wet Vac. Allow the flagstone's surface to fully dry.
- Apply a stone-penetrating sealer to the flagstone, following the manufacturer's directions. Use a paintbrush or paint roller to apply the sealer. Wait for the sealer to fully dry between coats. Apply two coats or more as directed by manufacturer.
How to Refinish Flagstone
Most of the time, when people mention flagstone they are actually referring to sandstone, which is a porous, sandy stone made mostly of quartz. The sandstone is cut into randomly shaped large-sized pieces and used as a patio or garden path. The flagstones become dirty due to foot traffic, tree debris and soil runoff from rainstorms. Once every year or two you should refinish, or seal, the flagstone to extend its life and maintain its appearance.