Stone and brick cleaning can produce fantastic results. Both are strong enough to withstand a light pressure wash with no detrimental effect to the integrity of the substrate. Aggressive blasting is not usually required as once the type of soiling is identified, the appropriate chemical treatment will help the job go smoothly.
There are two main types of pollutant-
Carbon deposits from traffic pollution, and on older buildings a build up of carbon from years of chimneys pouring out smoke. This needs a specific acid treatment and a light pressure wash
Living matter forming on the surface. If the right conditions exist ( dark and damp ) then mould, algae and even lichens will form. This is often in areas where rainwater run off is prevalent. To remove this infestation we treat with a professional biocide and a light pressure wash.