Patent ID: 7375069

Claim:
A method for masking and subsequently removing unsightly stains from rugged solid surfaces comprising the steps of: (a) providing a rugged, solid surface having a consistent color with a stain of a different color than the surface selected from the group consisting of asphalt pavement, concrete, marble and stone; (b) coating the entire stain with a durable thin film of a composition consisting essentially of: titanium dioxide as a photocatalyst, a dopant selected from the group consisting of platinum, tin oxide, and mixtures thereof, a co-reagent selected from the group consisting of oxalic acid, citric acid, sodium citrate, potassium hydrogen tartrate, sodium phosphate, sodium hydrosulfite and silicic acid that masks the stain; and (c) exposing the coated stain to an environmental element selected from the group consisting of a light source and air, rain, humidity, pedestrian traffic vehicular traffic or a combination thereof that degrades and removes the stain from the surface.