Blackening Chemicals Processes * Blackening Chemicals Blackening chemicals are used to create a protective black oxide or phosphate coating on metal surfaces. This process enhances corrosion resistance, wear resistance, and aesthetics while maintaining tight tolerances. Blackened surfaces are commonly used in automotive, firearms, tools, machinery, and industrial equipment. 1. Types of Blackening Processes & Chemicals A. Hot Black Oxide (Alkaline Blackening) Produces a deep black, durable oxide layer. Best for steel, stainless steel, and iron. Involves immersing metal in a 145–150°C (293–302°F) alkaline bath of sodium hydroxide and nitrates. B. Cold Blackening (Cold Black Oxide) A room-temperature alternative for steel, iron, and some stainless steels. Used where heat treatment isn’t feasible. Less durable than hot black oxide but faster and safer. # Blackening Chemicals Manufacturer.