Jax Iron, Steel and Nickel Blackener All Jax metal finishing and polishing solutions are easy to use, produce authentic, consistent results, require no heat or electricity, are water-based, contain no sulfur, are non-flammable and react within seconds. Jax Iron, Steel and Nickel blackener produces an antique, metallic black finish in seconds on iron, steel, and nickel. Available in 2 oz. and 1 pint sizes.