Best Blackening Chemicals - Blackening is a surface treatment commonly used to darken metal parts, improve corrosion resistance, reduce glare, and enhance aesthetics. The process, often called "black oxide" for ferrous metals, creates a thin, chemically bonded black coating that doesn\'t significantly affect part dimensions. Here’s a list of effective blackening chemicals for various metals: 1. Cold Black Oxide (for Steel) - Process: Room temperature blackening, typically used for applications where high temperatures are not feasible. - Chemicals: Copper selenide or selenium dioxide. - Advantages: Easier to apply and less equipment-intensive than hot black oxide, though slightly less durable. # Blackening Chemicals Manufacturer.