Copper stain is the name given to the unsightly green deposits often found on masonry surfaces below copper, bronze, or brass roofing, flashing, plaques, or decorative elements. It is caused by atmospheric pollutants dissolving some of the copper and transporting it to the masonry surface where it reacts to form insoluble copper salts attached to the masonry. Dense masonry such as granite and cast stone or light accumulations on other substrates can often be cleaned in one step. Heavier buildups accum