Blackening Products For Metal Surfaces - Blackening products for metal surfaces are used to provide corrosion resistance, aesthetics, and anti-reflective properties. The process is often called black oxide coating, cold blackening, or hot blackening, depending on the method used. * Types of Blackening Products for Metal Surfaces 1. Cold Blackening (Cold Oxide) Best for: Steel, iron, and some stainless steels. Process: Room-temperature immersion in a selenium-based solution to form a black coating. Benefits: Quick application, low energy cost, but less durable than hot black oxide. Examples: Birchwood Casey Presto Black Blackfast 181 Cold Blacking Solution 2. Black Phosphate Coating Best for: Steel and iron. Process: Phosphating with manganese or zinc, followed by an oil topcoat. Examples: Parkerizing solutions # Blackening Chemical Manufacturer.