This room temperature chemical is used by gunsmiths to blacken alloy parts (also known as cold blue). Restores scratched and marred areas quickly and its simple to apply. Colour will vary from deep grey to black depending on the aluminum to which it is being applied. Alloy metal black is also excellent for blackening name plates, plaques, trophies and other engraved items. 3 oz Liquid. * I also have Birchwood Casey "Blue and Rust Remover Liquid" listed. * I also have Birchwood Casey "Blueing" for steel listed. one courier cost to courier any two together.