The first few days
Give the stone time to dry fully before judging the result. Indian sandstone is naturally variable and looks considerably darker wet than dry, and different slabs release moisture at different rates, so a patio can look blotchy for a day or two and even out afterwards.
Keep heavy furniture, planters and anything with metal feet off the surface until it is dry, and avoid dragging things across it. If jointing has been renewed as part of the work, follow whatever curing advice was given on the day before putting the area back into full use.
Simple habits that make the difference
- Sweep regularly — most staining starts as organic debris left to break down on the surface.
- Clear leaves, blossom, berries and pine needles promptly, particularly in autumn.
- Rinse spills quickly, especially barbecue grease, oil, wine and anything acidic.
- Move planters and furniture occasionally so damp patches do not become permanent marks.
- Keep gullies, channels and drainage runs clear so water leaves the surface.
- Trim back overhanging planting to let more light and air onto shaded areas.
Drainage matters more than scrubbing
Almost every recurring problem on a sandstone patio traces back to water sitting somewhere it should not. Standing water keeps the stone damp, and damp stone grows lichen, algae and moss.
Look at the patio during heavy rain. Water should run off towards the intended fall and away from the house. Puddles that persist for hours, a blocked gully, a downpipe discharging onto the slabs or a raised bed washing soil across the surface are all worth dealing with — they will undo a clean far faster than foot traffic will.
Black spot and what to expect
Black spot lichen is common on Indian sandstone in the North West. It bonds tightly to the stone, which is why it survives ordinary washing and returns on shaded, damp patios.
Professional cleaning can give a real improvement, but it is honest to say that heavily established black spot may reduce rather than disappear entirely, and that it can come back over time in the same conditions that produced it. Anyone promising permanent removal is overselling.
The practical approach is to improve the light, air and drainage where you can, keep the surface swept, and accept a maintenance clean at sensible intervals rather than chasing a permanent fix.
What to avoid
Strong acids and neat bleach are the two most common causes of damage we see on natural stone. Acids can etch the surface, lighten the colour unevenly and attack pointing and mortar joints. Bleach can leave patchy discolouration that is harder to live with than the original staining.
Wire brushes and aggressive scouring wear the surface and leave marks that catch dirt afterwards. Domestic pressure washers held too close, or used with a narrow jet, cut lines into softer stone and blow out jointing.
If you want to try a product, test it on a spare slab or a hidden corner and give it time to dry before deciding.
Where sealing fits in
Sealing is a separate service from cleaning and is not automatically the right answer. Whether it is worthwhile depends on the stone, its condition, the drainage and how the area is used — some installations benefit noticeably, others gain very little.
It also has to be applied to a properly cleaned, dry surface in suitable weather, which is why it is planned as its own stage rather than tacked onto a wash.
If you are considering it, ask for a view on your specific patio. We would rather explain honestly where it will and will not help than sell it as standard.