Guide
Patio black spots: when a pressure washer is not enough
Why lichen/black spots often need treatment, dwell time, surface caution and test patches rather than a more powerful washer.
Quick answer
Black spots are often lichen embedded in the surface. A stronger jet can damage stone before it removes the marks. Treatment, dwell time and gentle follow-up cleaning may be the better plan.
Typical example
Indian sandstone that still shows black dots after close-pressure washing may need a stone-suitable black-spot treatment, not a closer nozzle that strips the face.
Checks before hire
- Confirm stone type and sealer.
- Use a product suitable for the surface.
- Protect plants, drains and adjacent materials.
- Do a small test patch before treating the whole patio.
When to stop
- Stop if the stone face starts lifting, sand washes out, runoff cannot be controlled, or the treatment is unsuitable for the surface.
Turn it into a hire card
Use the matching planner to turn this note into a practical kit class, consumables list, PPE checks and copyable handoff summary.
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