Black spot & lichen removal in Ilkley
Tiny black dots that won't scrub off natural stone.
Nine times out of ten, the black dots on a Ilkley sandstone patio aren't dirt — they're lichen with roots inside the stone, which is why the jet-wash never quite gets them off.
We work Ilkley and the surrounding LS29 postcodes every week, so this isn't a job we're travelling to — it's on the round.
What we use, and why
A stone-safe alkaline black-spot remover with a controlled dwell — pressure alone won't shift lichen from Indian sandstone or riven Yorkshire flags.
Causes in LS29
- 1airborne spores settling on porous, unsealed slabs
- 2lichen fungus rooting into the calcium in natural stone
- 3previous pressure-only cleaning that scoured pores open
The tell-tale signs
- grey-white lichen crusts on older Yorkshire stone
- shadow-side staining that survives ordinary pressure washing
- spots that reappear within weeks of a normal jet-wash
- pin-head black spots welded into sandstone flags
How we fix it
spot survey to grade coverage — light, moderate or crusted
extended dwell with a stone-safe black-spot remover (not neat bleach)
controlled agitation, never a rotary onto weathered sandstone
neutralising rinse and pH test on natural stone
optional impregnating sealer to slow re-colonisation
When to book
Warm, dry stretches from May to September give the best kill; cold treatments extend dwell times and can leave shadowing on natural stone.
Every month untreated, the lichen roots deeper — after two summers it can etch into the stone and leave a permanent shadow even after removal.
Keeping it fixed
Apply an impregnating (breathable) sealer after cleaning, keep debris off the surface, and re-treat lightly at 18–24 months.
Ilkley FAQs
- Will bleach get black spot out of my Ilkley patio?
- Domestic bleach lifts the surface colour but rarely kills the lichen root inside reclaimed York stone and honey-toned setts — the spots return within a season.
- Can you use a rotary on my sandstone?
- Not on weathered reclaimed York stone and honey-toned setts — we hand-agitate with a stone-safe treatment and only rotary the pointing where we've protected the stone edges.
- Do you seal the patio afterwards in LS29?
- Optional — we use a breathable impregnating sealer that doesn't glaze the surface. Adds around 18–24 months to the clean interval in Ilkley.
- How long does the treatment take?
- A typical Ilkley patio (25–40 m²) is a one-day job: dwell in the morning, agitate and rinse after lunch, neutralise before we leave.
- Will the stone lighten unevenly?
- No — we test a small panel first at your LS29 address, then treat the whole surface at the same dilution so the finish is uniform.
A properly treated and sealed Ilkley patio should give you five clean summers before it needs another look.
Send a close-up photo from your Ilkley address and we'll grade the coverage, quote firm, and book a dry-weather slot.
Get a free Ilkley quoteReady for a free, fixed quote?
Send us a few details and we'll come back within 24 hours with a firm price — no obligation.