STAIN-PROOF® Acidic Cleaner, formerly known as EFF-ERAYZA™  is a new technology acid cleaner for removing efflorescence, rust stains, limescale, grout haze, mortar mess and fireplace soot. Acidic Cleaner is very powerful and generally more effective and safer to use than traditional industrial acids but does not produce noxious fumes, is non-corrosive to metals (except for uncoated aluminium) and temporary contact does not burn skin.