Rust & Scale Remover is a powerful, highly concentrated, non-phosphoric acid solution for tackling tough rust and scale build-up on various surfaces. . Its potent formula delivers professional-grade results without the harshness of traditional, phosphoric acid-based products. . Ideal for: Metals (Chrome, stainless steel, iron, aluminum, silver, copper), Hard Surfaces (Tiles, bathtubs, sinks, showers, tools), Outdoor: (Patio furniture, grills, tools, boats), Automotive (Wheels, exhaust pipes, chrome trim), Glass (Windscreen, windows and mirrors) . Test in inconspicuous area first Direction of use: . Apply it to the surface you want to clean as is. (Can be diluted up to 1:5 for removing scale.) . Let the solution sit on the surface for a few minutes, depending on the build up severity. . Use a brush or sponge to evenly clean the surface. . Use water to rinse the surface of any remaining solution then dry it well.