How to Deal With Black Spots on Indian Sandstone
Alex Mcdonald23 September 2026 · 3 min readThose stubborn black dots on Indian sandstone are usually lichen, not dirt. That's why a quick wash leaves them behind.
Why the spots won't wash off
Lichen roots itself into the surface of the stone. Washing removes surface dirt and green algae, but the black spots stay put because they're anchored into the pores.
How they're treated
After a thorough clean, a specialist treatment is applied to the affected areas. It works over the following days and weeks, and the spots gradually fade as the lichen breaks down and weathers away.
Patience pays off here. Results build over time rather than all at once.
Keeping your patio looking fresh
- Sweep regularly to stop debris holding moisture
- Keep plant pots off the stone where possible
- Book a light maintenance clean once a year