Goof Off RustAid Outdoor Rust Remover spray works on a variety of outdoor surfaces to neutralize and dissolve tough rust stains caused by well water, lime scale and calcium deposits. RustAid is safe for use on a variety of outdoor surfaces including concrete, stucco, wood, fiberglass, brick, painted surfaces and vinyl siding. Apply to an exterior wall, walkway, foundation, driveway, fence, shed, or lawn furniture. This rust eraser and hard water stain remover will leave your surfaces looking renewed and is safe for plants and grass. To use, simply spray on and rinse off, no need for scrubbing. Watch as it eliminates tough stains and gets other outdoor surface rust out like magic.