There is a small fee for samples shipped in the continental U.S. This can range from $10-$75. Products shipped outside the continental U.S. can be subject to certain restrictions. Freight charges may range from $75-$300.

Black Oxide

The Black Oxide process has been researched and developed by EPi  for over 60 years. 



The lab's  research of black oxide has resulted in EPi leading the way in black oxide and becoming the first black oxide chemistry supplier to develop three processes of black oxide chemistry:


  • Hot Black Oxide - 285°F - Ultra-Blak 400
  • Mid Temperature Black Oxide - 225°F – Kool-Blak 225
  • Room Temperature Black Oxide - 70°-80°F – Insta-Blak 333


Any of EPi’s black oxide processes can be used in-house saving finishing costs, cutting lead time and increasing productivity. EPi’s black oxide processes are perfect for Lean Manufacturing companies.

 Is your present black oxide process resulting in a smutty finish?  Switch to one of EPi’s black oxide processes to eliminate common smut problems with other room temperature black and mid temperature black oxides.

Ultra-Blak 400 and Kool-Blak 225 meet MIL-C-13924 and AMS 2485 specifications, and passes the oxalic drop test – the ultimate quality control test for black oxide coatings.

Looking to black oxide in-house?  Send sample parts by printing, completing and returning this In-House Black Oxide Form.


Black Oxide Applications

  • Firearms & Military
  • Tool & Die, Stamping, Tubing
  • Fasteners, Washers, Screw Machine
  • Oil field & Drilling Components
  • Automotive - Mounting, Brake Hardware, Spark Plugs
  • Gears, Shafts, Bushings
  • Architectural
  • Power & Hand Tools
  • Medical Fixtures
  • Powder/Sinter Metal (Insta - Blak 333)


Why Blacken?

1. Dimensional Stability: Blackening process produces essentially no dimensional change with only 5 to 10 millionths of an inch added to the dimension, which means the blackened parts retain their surface properties with polished surfaces retaining their gloss and heat-treated parts retaining their Rockwell hardness. Tool integrity is preserved and critically sized parts can be finished with no worries.

2. Anti-Galling: When it's necessary to break-in mating parts, the anti-galling surface sacrifices the lubricating layer of black during initial contact and abrasion while a work-hardened surface is formed.

3.Pleasing Esthetic Appeal: Produces a pleasing decorative black finish which enhances the perceived quality of the part, improving the stability of the part.

EPi offers a Black Oxide Trifecta with its advanced hot, mid-temperature, and cold black oxide processes!

Hot Black Oxide- Ultra-Blak 400 is a sodium hydroxide oxidizer nitrite/ nitrate bath for steel that operates at 285ºF. Approximate blackening time: 10-20 minutes. Ultra Blak 400 offers incredible abrasion resistance, produces a deep rich blue/black color and meets the Military Spec 13924 D and AMS 2485

Mid Temperature Black Oxide- KOOL-BLAK 225 is a sodium hydroxide nitrite/nitrate bath for steel that operates at 220º-245ºF. Approximate blackening time: 30-45 minutes. KOOL-BLAK 225 does not require boiling, is completely smut free and meets the Military Spec 13924 D and AMS 2485.

Room Temperature Black Oxide- Insta-Blak 333 is a phosphoric acid, selenium and copper bath that operates at 65º-85ºF. Approximate blackening time: 1-5 minutes. Insta Blak blackens a variety of metals, it is simple to use and provides considerable energy cost savings.

Blackening Sample Kits available.

EPi provides superior solutions for blackening for steel, but also has quality, efficient, innovative solutions for a variety of other metals. For more information on any of these metals, click the link below:

Check out our Black Oxide Audio/Video Series on You Tube or download EPi’s Black Oxide FAQ's.