Finish specification

MIL-A-8625

The military specification for anodic coatings on aluminum and aluminum alloys, from thin chromic acid films to Type III hard coat.

19,091 NSNs in DLA's catalog cite this spec. See the catalog data

What MIL-A-8625 covers

MIL-A-8625 covers anodic coatings for aluminum and aluminum alloys. It covers sulfuric acid anodizing (Type II), hard anodizing (Type III), chromic acid processes (Types I and IB) and their non-chromate alternatives (Types IC and IIB).

A callout normally names both a type (the process) and a class (dyed or not), for example MIL-A-8625 Type II, Class 2.

Types and classes

Type I
Chromic acid anodizing.
Type IB
Chromic acid anodizing, low voltage process (22 ± 2 V).
Type IC
Non-chromic acid anodizing, for use as a non-chromate alternative for Type I and IB coatings.
Type II
Sulfuric acid anodizing.
Type IIB
Thin sulfuric acid anodizing, a non-chromate alternative to Type I and IB coatings.
Type III
Hard anodic coatings. Unless the contract, order or drawing says otherwise, the nominal thickness is 0.002 inch (2 mils).
Class 1
Non-dyed.
Class 2
Dyed.

Status and revisions

The current revision is MIL-A-8625F, dated 10 September 1993, with Amendment 1 dated 15 September 2003.

Notice 1, dated 28 August 2019, records that MIL-A-8625F has been reviewed and determined to be valid for use in acquisition.

Typical applications

  • Corrosion protection and dyed finishes on aluminum parts (Type II, Class 1 or 2).
  • Wear-resistant hard coat on aluminum (Type III).
  • Non-chromate alternatives where Type I or IB was used, with the procuring activity's approval (Types IC and IIB).
  • In DLA's catalog it is called out most often on sleeve spacers, solid and blind rivets, spur gears, flat washers and panel screw assemblies, led by 2024, 7075 and 6061 aluminum.

What a shop needs to supply to MIL-A-8625

  • Run the type and class the drawing names. Substituting Type IC or IIB where Type I or IB is specified is prohibited unless the procuring activity approves it.
  • Sealed Type I, IB, IC, II and IIB coatings are tested with 336 hours of 5 percent salt spray per ASTM B117.
  • For Type III, hold the thickness the drawing specifies, or 0.002 inch nominal by default. Up to 0.002 inch, thickness may vary by no more than 20 percent unless otherwise specified.
  • Plan the machining dimension for growth. The spec's design notes say to expect a dimensional increase of about half the coating thickness on each surface, and recommend putting both a machining dimension and a coated dimension on the drawing.

The purchase order, drawing and the revision of the spec it invokes govern. Always work from the revision your contract names.

MIL-A-8625 in the DLA catalog

From DLA's public PUB LOG catalog, release 2026-10-27, covering 16 hardware and mechanical supply groups (fasteners, bearings, fittings, valves, power transmission, engine components and more).

19,091
NSNs whose catalog record cites MIL-A-8625
39%
coded open to new sources (7,400 NSNs): at least one managing service codes it AMC 1 or 2 with AMSC G
38%
coded for existing or approved sources (7,251 NSNs)

Most common items

Spacer, sleeve1,957
Rivet, solid1,917
Rivet, blind1,227
Gear, spur963
Washer, flat733
Screw assembly, panel529
Nut assembly, self-locking, gang c511
Spacer, plate453
Coupling half, quick disconnect409
Pin-rivet365

Federal supply classes

5320 Rivets3,806
5365 Bushings, rings, shims, and spacers3,177
5340 Hardware, commercial2,666
5310 Nuts and washers2,501
4730 Hose, pipe, tube, lubrication, and railing fittings2,300
3020 Gears, pulleys, sprockets, and transmission chain1,280
5305 Screws591
4820 Valves, nonpowered468

Can a new source win these parts?

DLA codes each part with an acquisition method (AMC) and a suffix (AMSC). We count an NSN as open when at least one managing service codes it AMC 1 or 2 (competitive) with suffix G (the government has the full technical data and the rights to use it). Otherwise we count it as restricted when a service codes it AMC 3, 4 or 5 (buy from the manufacturer or prime) or uses a suffix that limits or conditions who can supply it (AMSC B, C, D, H, K, L, P, Q, R, T, U or Y): missing data or rights, source-control drawings, source or QPL approval, controlled castings, uneconomical breakout, an unstable design, or low-value screening for known sources. These are catalog codes; the solicitation always governs.

Open: AMC 1 or 2 with AMSC G7,40039%
Restricted: AMC 3, 4 or 5, or a restrictive AMSC7,25138%
Other acquisition codes1,92010%
No acquisition method in the catalog2,52013%

As of PUB LOG release 2026-10-27. How to read the codes: AMC and AMSC codes explained.

How catalog records call it out

Characteristic records that cite MIL-A-8625, grouped by the type, class or condition they name. Counted across the most common callout spellings, so the totals are a floor.

Not specified7,905
Type 12,536
Type 21,885
Type 2, Class 11,037
Type 2, Class 2424
Type 1, Class 1285

Materials these parts are made from

  • Aluminum alloy 2024 (overall) 4,061
  • Aluminum alloy (overall) 1,126
  • Aluminum alloy 7075 (overall) 1,071
  • Aluminum alloy 6061 (overall) 1,046
  • Aluminum alloy 2117 (overall) 838
  • Aluminum alloy 6061 748
  • Aluminum alloy 2024 543
  • Aluminum alloy (body) 534

Sample NSNs that cite MIL-A-8625

Anodizing shops in the directory

9 listed shops report this capability. Confirm the spec, revision and any approvals with the shop before you order.

See all anodizing shops

Frequently asked questions

What is MIL-A-8625 Type II?

Type II is sulfuric acid anodizing. It is usually paired with a class: Class 1 is non-dyed and Class 2 is dyed.

What is MIL-A-8625 Type III?

Type III is hard anodic coating. Unless the contract, order or drawing says otherwise, its nominal thickness is 0.002 inch (2 mils).

Is MIL-A-8625 still active?

Yes. Notice 1, dated 28 August 2019, states that MIL-A-8625F has been reviewed and determined to be valid for use in acquisition. Revision F is dated 10 September 1993 and was amended on 15 September 2003.

How much does anodizing change part dimensions?

The spec's design notes say to expect an increase of about half the applied coating thickness on each surface, which matters most for Type III. They recommend showing both a machining dimension and a coated dimension on the drawing.

What salt spray test does MIL-A-8625 require?

Sealed Type I, IB, IC, II and IIB coatings are exposed to 5 percent salt spray per ASTM B117 for 336 hours.

Related

Sources