EPi is the only supplier to offer all three types of processes for steel blackening, which are differentiated by the temperature at which the solution will properly blacken the steel.

Black Oxide is a blend of caustic oxidizers and additives that are used to blacken ferrous metals. The black-oxide coating is produced by a chemical reaction.

The result is the formation of black oxide on the surface of the metal being coated. In-house metal blackening offers a variety of advantages, including:

  • Dimensional stability
  • Anti-galling properties
  • Smut-free, deep black finishes
  • Aesthetic appeal

Hot-temperature black oxide (285 F°) is a conventional hot process which produces a true black oxide iron magnetite (Fe3O4) finish. It is a premium-grade salt mixture which will blacken a wider range of steel alloys than any other process on the market.

Select a hot black-oxide process to:

  • Blacken parts in 10–20 minutes
  • Produce a glossy blue-black color
  • Create impressive abrasion and corrosion resistance
  • Finish hard-to-blacken metals 5–10 minutes faster
  • Produce no dimensional change
  • Generate less sludge
  • Blacken without baking, excessive handling, or producing volatile fumes
  • Save money thanks to a low product-to-water ratio

Featured products: Ultra-Blak 400, Ultra-Blak 400-L, and Ultra-Blak Rectifier


Mid-temperature black oxide (225–255 F°) is the latest development in blackening processes, producing a true black oxide iron magnetite (Fe3O4) finish. It produces no caustic boiling fumes and provides a safer working environment.

Select a mid-temperature process to:

  • Blacken metals in 30–45 minutes
  • Produce glossy black appearances
  • Achieve a uniform finish
  • Create smut-free, abrasion-resistant finishes
  • Blacken in a variety of methods
  • Save energy in heating costs
  • Pass oxalic acid military tests
  • Create safer working environments

Featured products: Kool-Blak 225


Room-temperature black oxide (65–85° F) is the preferred metal-blackening process for safe and convenient in-house blackening. It is an excellent non-bleed black finish for powdered metal and cast iron. It produces super deep blackness and corrosion resistance equal to hot oxide blackeners.

Select a room-temperature process to:

  • Blacken parts in 1–5 minutes
  • Produce grey-black satin finishes
  • Resist corrosion
  • Blacken cast iron, forged steel, tools, or powdered metals
  • Save money in heating costs

Featured products: Insta-Blak 333 and Insta-Blak 333 GEL