MIL-A-8625 anodizing for aerospace and defense.
Argent partners with the U.S. anodizers still qualified to ship to MIL-A-8625 — Type I chromic, Type II sulfuric, and Type III hardcoat. Class 1 (undyed) and Class 2 (dyed) finishes for aluminum alloys used in aerospace structural, electronic enclosure, and defense applications.
MIL-A-8625: the U.S. aerospace anodizing standard.
MIL-A-8625 (current revision: MIL-A-8625F with Amendment 1) is the U.S. military specification for anodic coatings on aluminum and aluminum alloys. It defines three types of anodizing and two classes of finish, each with specific corrosion resistance, wear resistance, and dielectric performance requirements. MIL-A-8625 is referenced by virtually every major aerospace and defense program for aluminum part finishing.
The three MIL-A-8625 types
- Type I — Chromic acid anodize. Thinnest coating (0.00002–0.0003 in / 0.5–7 μm). Used where dimensional change must be minimized, on parts with tight tolerances or thin walls, and on aluminum alloys with high copper content (2024, 7075) where sulfuric anodize causes corrosion issues. Preferred for fatigue-critical structural parts where the thicker sulfuric coating would reduce fatigue life.
- Type II — Sulfuric acid anodize. Standard aerospace anodize. Coating thickness typically 0.0002–0.001 in (5–25 μm). Good corrosion resistance, accepts dye well (Class 2), and is the most common aerospace anodize for aluminum enclosures, brackets, and general structural parts.
- Type III — Hardcoat anodize. Thick, dense coating (0.0005–0.004 in / 12.5–100 μm) with high abrasion and wear resistance. Used on parts that see sliding contact, abrasive environments, or require electrical insulation. Common on aerospace landing gear components, electronic chassis, and defense weapon system parts.
Classes
- Class 1 — Undyed (natural). The natural color of the anodic coating, which varies from clear-silver (Type II) to gray-brown (Type III hardcoat). Used where the natural appearance is acceptable or where color is added by a topcoat.
- Class 2 — Dyed. Coating impregnated with dye after anodizing, typically in black, blue, red, gold, or other standard aerospace colors. Common for visual identification, branding, or to meet specific stealth/IR requirements.
Why aerospace anodizing capacity is shrinking in the U.S.
If you have been quoting aerospace anodizing recently and the lead times feel impossible — or shops are no-bidding work they would have taken five years ago — you are seeing a real industry trend, not bad luck.
EPA permitting requirements for anodizing chemical lines have tightened significantly. Sulfuric, chromic, and chromate-based passivation processes generate hazardous waste streams that must be permitted, monitored, and disposed of under increasingly strict standards. The capital cost of bringing a new anodizing line online — permits, scrubbers, wastewater treatment, ventilation — has grown faster than the price aerospace customers are willing to pay for the work.
The result: aerospace anodizers have been closing or being acquired faster than new capacity comes online. Boeing has publicly flagged anodizing capacity as a supply chain risk. Defense primes have begun longer-term capacity agreements with the qualified U.S. anodizers that remain.
Argent maintains relationships with the U.S. anodizers still actively shipping to MIL-A-8625. We route aerospace anodizing work to partners with current capacity, current Nadcap accreditation where required, and current MIL spec qualification. For programs that need anodizing today and cannot get it quoted elsewhere, that’s exactly what we’re built to do.
What Argent can manufacture under MIL-A-8625.
Aluminum alloys we process
- 2024 — high-strength aerospace structural. Chromic anodize (Type I) preferred to preserve fatigue life.
- 6061 — general purpose aerospace, machined parts. Excellent response to Type II and Type III anodizing.
- 6063 — extruded parts, structural shapes. Good anodizing response.
- 7050 / 7075 — high-strength aerospace structural. Chromic (Type I) typically specified.
- 2219 — cryogenic and high-temperature aerospace structural.
- 5052 / 5083 / 5086 — marine and defense applications.
Pairs well with.
Argent customers typically combine multiple capabilities on the same program. These are the most common pairings with this work.