The exterior and interior surfaces of metallic
enclosures for militarized equipment shall be painted as specified herein,
except the interior of treated aluminum enclosures for sheltered locations
need not be painted. Prior to painting, the applicable pretreatment and primer
shall have been completed. Plastic enclosures normally will not be painted.
Paint system tests are specified in Appendix D
. The surface preparation shall result in a
least a 0.050 mm surface profile. The specifier of ruggedized equipment shall
review these requirements design features that may be required for the
specific application.
5.1.8.1 Adhesion and blister resistance. Paint systems
shall show no blistering or adhesive failure when tested as specified herein.
5.1.8.2 Aluminum and aluminum alloy pretreatment. Aluminum and aluminum
alloy pretreatment shall be as follows:
(a). Cleaning. the basic metal
shall be cleaned to remove grease, oil, welding flux, or other foreign
matter.
(b). Application.
(1) Protected equipment (interior use).
For protected equipment (interior use), aluminum and aluminum alloy parts shall
be anodized in accordance with MIL-A-8625, primed with material conforming to
TT-P-645. The topcoat shall match the surrounding structure.
(2) Exposed
equipment (exterior use). For exposed equipment (exterior use), aluminum and
aluminum alloys shall be coated in accordance with section 5.1.8.5.
5.1.8.3 Ferrous metal pretreatment. Ferrous metal pretreatment shall be
as follows:
(a). Cleaning. After all machining, welding, and brazing
operations are completed, rust or other corrosion products and flux shall be
removed by abrasive blasting, sanding, wire brushing, or other mechanical means.
Surfaces shall be cleansed of all grease, oil, and dirt by solvent wiping and
rinsing, vapor degressing, or caustic washing followed by rinsing.
(b). Application. Ferrous metals shall be pretreated in
accordance with type I or III of TT-C-490.
5.1.8.4.1 Primer. One coat of
primer in accordance with "TT-P-645B or TFP-664". The primer shall have a dry
film thickness of 0.015 millimeters (mm) to 0.020 mm.
5.1.8.4.2 Enamel. Enclosures shall be painted with two
continuous film coats of enamel in accordance with MIL-E-15090. Each coat shall
have a minimum thickness of 0.025 mm, dry film thickness. Enamel for shipboard
portable equipment enclosures shall be in accordance with class 1 of
MIL-E-15090. Enamel for other protected equipment enclosures shall be in
accordance with class 2 of MIL-E-15090.
5.1.8.5 Exposed equipment
(exterior use). Equipment or units thereof, exposed to the weather shall be
finished with four coats of paint in accordance with the following:
1st
coat: Epoxy-polyamide primer in accordance with MIL-P-24441 and MIL-P-24441/1
(0.075 mm to 0.100 mm fry film thickness).
2nd coat: Epoxy-polyamide top
coat in accordance with MIL-P-24441/6 or MIL-P-24441/3 (0.050 mm to 0.075 mm dry
film thickness).
3rd to 4th
coat: Silicone alkyd enamel in accordance with DOD-E-24635, color 26270 in
accordance with FED-STD-595 (0.025 mm to 0.040 mm dry film thickness). The total dry
film thickness shall be 0.18 mm to 0.25 mm.
5.1.8.6.1 Primer. Primer in accordance with MIL-P-23377 shall be applied with
a dry film thickness of 0.015 mm to 0.025 mm.
5.1.8.6.2 Topcoat. Two coats of urethane enamel in accordance with
MIL-C-83286 shall be applied. Each coat shall have a minimum thickness of 0.025
mm.
5.1.8.7 Colors. Colors for the painting of equipment shall be selected in
accordance with FED-STD-595.
5.1.8.8 Paint Systems. The forgoing specific guidance may not cover all
possible applications, when alternative paint schemes must be specified, the
treatment, prime coat and topcoat chosen shall all be compatible and shall be
selected in accordance with MIL-T-704. The use of hazardous materials is to be
avoided wherever possible; the use of lead- and chromate-containing coatings
shall be avoided when an approved alternative exists. Consideration shall be
given to the field maintenance of paint systems.
