MIL-STD-186F (MI)
5541; all others shall be spotted-in over the bare area and feathered over the old finish with wash primer. The wash primer will adhere to an acceptable degree to the adjacent finish but the adhesion will not be as outstanding at these edges as it is to bare metal. The wash primer may be omitted if thin scratches or small areas are involved.
5.5.4.13.4 Smoothness of wash primer and primer coats. The wash primer should be dry scuffed with kraft paper. The primer should be applied as smoothly as possible, since specks and occlusions will carry through to the topcoat and impart undesirable roughness to the final finish. In spraying primer, proper spray techniques are necessary to avoid dry overspray which results in excessive roughness. A properly applied primer film should be free from streaks, blisters, seeds, excessive silking, or other irregularities. Dry scuff sanding by hand, using
No. 400 or No. 320 sandpaper should be employed, as necessary, to remove specks of roughness that might carry through to the topcoats, but extreme care should be exercised to avoid removing the primer down to the pretreatment coating. Great caution is necessary to avoid gouging the surface of rivets and other protuberances and edges of faying surfaces with the sandpaper, and thus remove the primer to
bare metal, which results in subsequent susceptibility to corrosion. Should this occur, normal touch-up with primer should be accomplished. Areas where primer presents a distinctly rough appearance not removable by sanding should be stripped and new primer applied to the area involved. If bubbling of the wash primer and subsequent coatings are encountered on magnesium, it may be taken as evidence
of inadequate surface treatment of the magnesium. Such bubbled coatings should be removed immediately and the surface given a manually applied chemical surface treatment, followed by wash primer.
5.5.4.13.5 Final dry of the finish. The parts, after painting, shall be permitted to dry in a dust-free atmosphere for a sufficient time prior to moving to ensure that the paint is adequately dry and to avoid damage of the finish. Painted parts shall also be protected from condensing moisture and rain during the first 24 hours after painting. This time may vary somewhat depending on the temperature and type of paint used.
5.5.4.14 Application of CARC polyurethane paint. It is essential that MIL-C-46168 and MIL-C-53039 green 383 and MIL-DTL-64139 paint be applied at a dry film thickness of not less than 1.80 mils to achieve color uniformity and optimum camouflage characteristics. Because of the higher degree of transparency of this paint in both the visual and infrared regions of the spectrum, an application of 0.8 to
1.0 mils dry, which is the normal application for an olive drab paint, would allow both the visual and infrared light to partially penetrate the surface and reflect the substrate or base coating. This would cause both non-uniformity in visual color and poor camouflage properties. Due to the extreme flatness of the paint, the color will vary to a degree, depending upon the texture and type of substrate, plus the
orientation of the film and the direction by which the light hits the film. Acceptance of
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