Type II anodizing is conventional sulfuric-acid anodizing that converts the aluminum surface into a durable oxide layer — for corrosion protection, a paint and adhesive base, and dyeable cosmetic finishes. Gleco anodizes to MIL-PRF-8625 Type II (formerly MIL-A-8625) and AMS 2471/2472 at our AS9100D and ISO 9001:2015 certified Texas plants.

Type II Anodizing Specifications

Governing specs	MIL-PRF-8625 Type II (Type IIB thin-film); AMS 2471 (undyed) / AMS 2472 (dyed)
Classes	Class 1 non-dyed; Class 2 dyed
Thickness	~0.00007–0.0010 in
Salt spray (ASTM B117)	336 h on qualified panels
Sealing	Hot DI water, nickel/cobalt acetate, or dichromate
Dimensional impact	~50% of the film grows outward (small for Type II)
Typical uses	Housings, panels, machined aluminum, pre-paint base, dyed cosmetic finishes

Black anodized aluminum rings — Type II anodize, black dye. The color is in the pore structure of the oxide, not a coating on top of it.

See also: anodizing overview, Type II vs. Type III comparison, and chem film for conductive/grounding areas.

FAQ

Type II Anodizing FAQ

What is Type II anodizing?

Type II is conventional sulfuric-acid anodizing per MIL-PRF-8625 Type II. It converts the aluminum surface into a hard oxide layer for corrosion protection, a paint/adhesive base, and dyeable cosmetic finishes. It is electrically insulating.

What colors and classes are available?

Class 1 is non-dyed (natural); Class 2 is dyed — black, red, blue, gold, and more. Dyed anodize can fade in prolonged UV, and color match across alloys is approximate.

How much does the part grow?

Roughly half the oxide grows outward and half penetrates the surface, so dimensional change is about 50% of a thin (0.00007–0.0010 in) film — small for Type II, but worth noting on tight tolerances.

Type II or Type III — which do I need?

Type II for corrosion, cosmetics, and paint base; Type III hardcoat when the part slides, wears, or needs dielectric strength. See our Type II vs. Type III comparison.

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Type II Anodizing (MIL-PRF-8625)

Type II Anodizing Specifications

Type II Anodizing FAQ

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