Black spot is the single most common complaint we hear about patios in Leicester and Leicestershire. It looks like little dots of black tar that have been splashed across your slabs, particularly on Indian stone and sandstone. People scrub it, scrape it, even try to bleach it, and it stays stubbornly in place. Here is the honest truth about black spot removal in Leicester.
What black spot actually is
Black spot is a hardy lichen — a symbiotic organism made up of fungus and algae living together. It anchors itself into the porous surface of the stone and pressure alone does not lift it. You can blast it with a domestic jet washer until you have eroded the slab and the spots will still be there.
Why pressure does not work on its own
The lichen is below the surface as well as on top. To kill it properly you have to break it down chemically. Once it is dead, the pressure wash lifts the dead organic matter away and the stone shines back through. Skip the chemistry and you are simply wearing the slabs out.
The Jet Waves method
We apply a proper professional biocide. We let it dwell for the required contact time. We then return and rinse the patio with a controlled pressure wash and a rotary surface cleaner. In most cases the spots are gone after a single visit. Very heavily affected patios may benefit from a follow-up biocide a few weeks later.
Keeping black spot away
Black spot will eventually return — that is the nature of biological growth. To slow it down, keep the patio swept clear of leaf litter, trim overhanging branches that drip moisture onto the slabs, and consider an annual top-up biocide treatment in late autumn. We can apply this for you on a return visit.
Book a black spot treatment
If you are tired of looking at black spots on your Leicester patio, call us on 07732 187000. We will take a look, give you an honest opinion, and quote you in writing.