No scrubbing or rinsing required, it's as easy as that! Specifically formulated to effectively treat, remove and control growth or lichen, moss, mould and algae without any scrubbing and rinsing. Spray & Walk Away is not a rapid cleaner, it does not show immediate results, it works slowly and effectively over time with elements (rain and sun). DO NOT RINSE OFF. No hosing or scrubbing required, works over time, fully biodegradable, phosphate free and bleach free. Changes will occur in between 4 and 12 weeks. Works on a wide variety of surfaces.Can be used on a variety of surfaces including wood, paint, concrete, brick, paving, cloth, plastics and roof materials