Gtechniq W9 Water Spot Remove is a powerful water spot remover which is 100% coating safe. W9 features a three mechanism approach to removing water spots. It dissolves and removes salts, traps metal ions, which are commonly found in tap water. And finally removes silica scale which are traditionally very tough to eliminate. Hard water spots and silica scale will disappear from the exterior surface with ease and works well on water spots on glass too! W9 is safe for use on all paint types, including matte finishes.