Anodizing is an electro-chemical process used to increase the thickness of the natural oxide layer on the surface of aluminum parts. The process is called anodizing because the part to be treated forms the anode electrode of an electrical circuit. Anodizing aluminum increases the corrosion and wear resistance. Anodic films can also absorb dyes into the oxide for cosmetic effects.

All processes are done in accordance with applicable Military Specifications


MIL-PRF-8625, MIL-A-8625 Type I Class I, AMS 2470
• Chromic Acid Anodize
• Light Gray in Appearance
• Thin Aluminum Oxide Coating .00004″ – .0001″ Thick
• Used Mostly for Weldments in Aerospace and Marine Applications
• Chromic Acid Will Not Attack Welded Areas
• Non-Conductive coating
• Type I Class II (Chromic Acid Black)


MIL-PRF-8625, MIL-A-8625 Type II Class I, AMS 2471, AMS 2472
• Clear Sulfuric Acid Anodize
• Oxide Coating Thickness .0001″ – .001″ Thick
• Parts Will Be Sealed in a Dichromate Seal Unless Otherwise Specified
• Greenish In Appearance
• Other Seals Available: Nickel Acetate and Hot Water Seal — Silver in Appearance
• Non-Conductive Coating
• Application: Aerospace, Military, Medical, Marine, Auto, Commercial
Mil-8625 Type II Class II
• Dyed Sulfuric Acid Anodize
• Colors: Black, Gray, Blue, Turquoise, Brown, Gold, Red, Purple and Burgundy
• Custom Dyes Available Upon Request
• Proprietary Modified Seal to Protect Against Ultraviolet Dye Fading


MIL-PRF-8625, MIL-A-8625 Type III Class I, AMS 2469
• Hard Coat Sulfuric Acid Anodize
• Normal Thickness .001″ – .002″ Thick
• Non-Conductive Coating
• Excellent Abrasion Resistance
• 5052 & 6061 Alloys Light Gray to Dark Gray in Appearance
• 7075 Alloy Light Olive in Appearance
• 2024 Alloy Dark Olive in Appearance
• Tapped Holes Should Be Masked Prior To Hard Coating
• No Seal Applied for Hardest Surface Finish
• Nominal Hardness 55- 65 Rockwell C Scale
• Radius Should Be .005 Or Larger When Specifying Hard Coat
MIL-PRF-8625, MIL-A-8625 Type III Class II
• Dyed Black Hard Coat Sulfuric Acid Anodize
• Applications: Aerospace, Military, Marine, Medical, Auto, Commercial
• “Kalon” (Mil-63576, Type I) (AMS 2482) Proprietary Coating Consisting of Hard Coat with a Teflon Impregnation
Used For Metal to Metal Wearing Surfaces, Superior Corrosion Resistance

CHEM FILM MIL – DTL – 5541 Type I & Type II (RoHS Compliant)

The Military Specification referred to as MIL-DTL-5541, “Military Specification, Chemical Conversion Coatings on Aluminum and Aluminum Alloys” covers chemical conversion coatings formed by the reaction of chemical conversion materials with the surfaces of aluminum and aluminum alloys. The current specification (2009) is MIL-DTL-5541F, which superseded MIL-C-5541E in July 2006. The specification is approved for use by all departments and agencies of the United States Department of Defense (DoD). Although prepared specifically for DoD applications, the standard is used for many commercial applications as well.
The MIL-DTL-5541 specification covers chemical conversion coatings that form protective coatings by chemical reaction with aluminum and aluminum alloy; these coatings are categorized by the following types and classes.
Type I: Addresses compositions containing hexavalent chromium.
Type II: Addresses compositions containing no hexavalent chromium.
Class 1A: Provides maximum protection against corrosion, whether painted or unpainted. This is a relatively thick film used as a final finish or pre-treatment to paint or powder coating, and it is typically gold, brown, or yellow depending on coating weight and alloy.
Class 3: Provides protection against corrosion where low electrical resistance is required. This is a thin film providing low contact resistance, and the coating weight is lower as is the corrosion resistance. There may be some advantages using this thinner film in bonding applications. This film typically appears to be a lighter color of gold.
Mil-C-5541, Class I A , 3 — Mil-DTL-5541 Type I, II Class IA, 3
AMS 2473
• Type I , Class IA – Coating Yellow In Appearance – Maximum Corrosion Resistance
• Type I , Class 3 – Coating Clear or Yellow in Appearance
• Type II, Class 3 – Coating Clear – RoHS Compliant
• Conductive Coating
• Excellent Base Or Primer For Painting


Stainless steel can corrode in service if there is exposed iron contamination on the surface. Passivation is a chemical treatment applied to the surface of stainless steel to remove contaminants and assist the formation of a continuous chromium-oxide, passive film which protects the surface from corrosion.
Our citric and nitric acid solutions can passivate and treat various stainless steel alloys. Care must be taken in selecting and using passivation treatments to ensure the selected treatment will target the contaminant.

Passivated parts undergo verification testing. We employ a number of verification tests (Copper Sulfate, Humidity, Salt Spray, etc.) to ensure your parts have been properly passivated.
QQ-P-35 — ASTM A967, AMS 2700

Passivation of Stainless Steel
• Removal of Contaminates such as Iron Embedded In The Surface From Machining
• Application: Aerospace, Military, Medical, Marine, Auto, Commercial

High Humidity Testing

AMS-STD-753A METHOD 101, SAE AMS 2700F(SEC, ASTM A967/A967M-17(SEC14.2), QQ-P-35C(SEC 3.7.1)


  • This test method is used to detect anodic surface contamination, including free iron, on corrosion resistant steel after the passivation process. 
  • High Humidity Test chamber:     Thermotron’s 8200+ Controller features a touchscreen, color display, built by Thermotron’s highly-skilled software and hardware engineers specifically for use with an environmental test chamber.
Pre-penetrant Etch

Pre-Penetrant Etch (Pre-Etch): Honeywell Aerospace C129


  • The purpose of the Pre-Etch is to produce Aluminum casting surfaces free of soils, oil, grease, corrosion products, chemical residues, or any other material that could prevent the penetrant from entering discontinuities. 
  • The process of chemical etching is to remove a pre-determined quantity of material from the surface of the parts by calculating material removal rate and dwell time.
  • The chemical baths are maintained by daily, weekly, monthly analysis, such as Intergranular attack (IGA) test, Material removal rate, and etc.
Monthly Test Reports

Monthly Tests Reports
• Contact Resistance: MIL-DTL-81706B Section 4.5.5
• Salt Spray Test: ASTM B117-09
• High Humidity Resistance: AMS-QQ-P-35A Section
• Abrasion Resistance: Mil-PRF-8625/Fed STD-141 (6192.1)
• Adhesion Test- Fed-STD-141-Meth.6301.3 / Mil-PRF-23377J (4.5.4)

B&M Finishers, Inc 201 South 31st Street, Kenilworth, NJ 07033
phone: 908-241-5640