MIL-DTL-3390H
3.4 Finishes. The finished rings shall be free from corrosion, dirt, discoloration, and
areas of no finish. Finishes shall be as follows:
3.4.1 Black chemical. Black chemical finish shall conform to MIL-F-495.
3.4.2 Zinc-plate.
3.4.2.1 Zinc-plate without enameling. Zinc-plate without enameling shall conform to
type II or type III, service condition (SC) 3 of ASTM B633.
3.4.2.2 Zinc-plate with enameling. Zinc-plate with enameling shall conform to type IV,
SC3 of ASTM B633, followed by baking enamel. The enamel shall conform to 3.2.7.
3.4.3 Cadmium plate. Cadmium plate shall conform to class 1 or class 2, type I or
type II of SAE AMS-QQ-P-416.
3.4.4 Chromium plate. Chromium plate shall conform to class 1 of SAE AMS 2460.
3.4.5 Class 1 rings. All class 1 rings, except configuration L, shall be finished as
specified in 3.4.1.
3.4.5.1 Configuration L. Configuration L rings, except class 1 (1 inch x 7/8 inch), shall
be given a bright, polished finish. Configuration L class 1 rings (1 inch x 7/8 inch) shall be
given either a bright, polished finish or the chromium finish specified in 3.4.4, as specified
(see 6.2). The chromium plate thickness shall be not less than 0.0002 inch.
3.4.6 Class 2 rings. All class 2 rings, except configurations L and X, shall be given a
finish as specified in 3.4.2.2. The enamel coating shall level out to a uniform dry film thickness
without orange peel, wrinkles, drops, streaks, or areas of no film.
3.4.6.1 Configuration L. At the option of the supplier, configuration L, class 2 dee rings
shall be given either the finish specified in 3.4.2.1 or the class 2, type II finish specified in 3.4.3.
3.4.6.2 Configuration X. Configuration X, class 2 dee rings shall be given the type II or
specified (see 6.2).
3.4.7 Class 3 rings. All class 3 dee rings shall be given the finish specified in 3.4.2.2.
The enamel coating shall level out to a uniform dry film thickness without orange peel, wrinkles,
drops, streaks, or areas of no film.
3.4.8 Class 4 rings. All class 4 dee rings shall be ground and polished to a bright finish.
3.4.9 Class 5 rings. The surfaces of the class 5 dee rings shall have a smooth and
lusterless or semi-gloss finish. All surfaces shall be free of dirt, dust, and foreign matter
inclusion. The finish shall be produced from a die that has the cavity surfaces finished in a vapor
blast, water hone, or similar satin finish, and not result from the application of any protective
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