Black spots on the patio: why more pressure is not always the answer
You rinse away the green film, but the dark dots are still there. That does not automatically mean the patio needs a more aggressive blast.
First, establish what the mark is
Lichen is one possible cause. Staining, wear and the natural stone can also look dark, especially when wet. A close-up and a wider photograph help establish the pattern, but a photograph alone cannot reliably diagnose every mark.
Treat the material as part of the problem
The question is not just what removes a stain. It is what the paving and joints can tolerate. Tell us about the type of stone, any coating and products previously used. We assess compatibility and a discreet test area before proposing a treatment.
Agree an honest finish
A targeted treatment may improve the result but is not a guarantee of uniform colour. Permanent marks, patching and natural variation can become more visible once the dirt is removed. We discuss that before booking.
Avoid the stronger-is-better trap
Do not mix cleaning products or assume a product suitable for concrete suits limestone, plants or drainage. Follow manufacturer instructions. If the surface is delicate, damaged or uncertain, get it assessed rather than experimenting on the whole patio.
General guidance; the material and condition at your property decide the method. Published on 10 October 2026.
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