Metal Blackening Process - Metal blackening, also known as black oxide coating, is a chemical process used to create a corrosion-resistant, decorative, and low-reflective black finish on ferrous and non-ferrous metals. This process is commonly used in automotive, firearms, tools, and industrial machinery to enhance aesthetics and durability. * Types of Metal Blackening Processes 1. Hot Black Oxide (Hot Blackening) - Performed at 140-150°C using an alkaline sodium hydroxide and nitrate/nitrite solution. - Produces a deep black, corrosion-resistant finish. - Requires post-treatment with oil or wax to enhance protection. - Used for steel, stainless steel, and iron. 2. Cold Blackening (Cold Black Oxide) - A room-temperature chemical conversion coating. - Easier to apply but provides lower corrosion resistance compared to hot black oxide. - Typically followed by an oil or sealant for better protection. - Used for mild steel and iron in low-wear applications. # Blackening Chemical Manufacturer.