How to Clean Indian Sandstone (Without Ruining It)

Step-by-step gentle cleaning method

Start by sweeping off loose debris, then apply a patio cleaner specifically labelled safe for natural stone, diluted according to the instructions, and leave it to dwell for the recommended time so it can work into any algae or grime without needing aggressive scrubbing. Rinse thoroughly with a hose or a pressure washer on a moderate setting, holding the lance at a reasonable distance and keeping it moving to avoid etching lines into the stone's surface.

For established green or black staining, a second application may be needed, but resist the urge to increase pressure washer intensity as a shortcut, since sandstone's soft, layered structure is easily damaged by concentrated high pressure. Working in small sections and keeping the surface consistently damp during cleaning also helps avoid the patchy, uneven look that can result from letting cleaner dry unevenly across a larger area.

Acid warnings worth taking seriously

Acid-based patio cleaners, including some popular high-strength products marketed for driveways, can etch and discolour sandstone and other natural limestone-family stone, sometimes permanently. What works safely on concrete or man-made block paving is not automatically safe on natural stone, and it is a mistake we see cause real, irreversible damage. Always check a product is explicitly labelled safe for natural sandstone before using it, and test on an inconspicuous area first regardless. Fizzing or bubbling on contact is a clear warning sign that a product is reacting with the stone and should be rinsed off immediately.

Sealing after cleaning

Once fully clean and completely dry, usually a few dry days after washing, applying a breathable sandstone sealer protects the stone from staining, slows algae regrowth, and often enhances the natural colour variation in the stone. Skipping this step means the pores stay open and exposed, so grime and organic growth re-establish faster than on a sealed surface. A moisture meter reading, or simply checking that the stone no longer feels cool and damp to the touch, is a reliable way to confirm it's genuinely dry enough before sealing.

DIY or professional?

A small, lightly soiled patio is a reasonable DIY job with the right natural-stone-safe products and a bit of patience. Larger areas, heavily stained or long-neglected sandstone, or anyone unsure about product safety on their specific stone, are better served by a professional clean, which typically runs from around £4 to £7 per square metre and includes sealing as an optional add-on.