Great for rust stains caused by well water sprinklers. Safely cleans exterior walls, foundations, driveways, and more. Safe for plants and grass. RustAid is specially formulated to work with oxidized iron to neutralize and remove tough well water rust stains from most outdoor surfaces. No rubbing or scrubbing is needed. Stains simply dissolve away. It can also be used to remove lime scale and calcium deposits. Use on the following surfaces: Concrete, stucco, wood, fiberglass, brick, painted surfaces, and vinyl siding. Great results outdoors. Walls, walks, driveways, fence, shed, and lawn furniture. Boat deck, boat cover, and sail canvas. Easier and less expensive than sealants when painting over rust-stained walls. Rated No. 1 in lab tests. Gallon. DampRid.