Blackening Chemicals Reviews - Types of Blackening Processes 1. Cold Blackening: Uses room-temperature chemical baths to produce a black finish. It is less hazardous and more convenient than hot blackening but typically offers lower corrosion resistance. 2. Hot Blackening: Involves immersing metal in a series of heated alkaline baths to produce a durable black oxide finish. It provides excellent corrosion resistance and a deep black color but requires more complex equipment and safety precautions. 3. Mid-Temperature Blackening: A process that operates at temperatures between cold and hot blackening, offering a balance between ease of use and durability.