TT-C-490F
3.5.1 Type I and type V, zinc phosphate. Type I and type V coating deposits shall be gray to black in color. The coating shall be uniformly colored and be free of smut, powder, corrosion products, or white residues. Nonuniformity of color due to heat treatment, composition of the base metal, the degree of
cold work performed on the base metal or presence of brown or orange stains inherent from the acidified final rinsing process shall not be cause for rejection.
3.5.2 Lighting conditions. A minimum light intensity of 50 lumens/ft2 or 538 lux shall be provided at
the working surface where manually controlled paint finish operations are performed. Minimum lighting shall apply to the final inspection areas (see 4.7.1.1).
3.5.3 Phosphate coating weight (types I, II, and V). Coating weight shall be controlled and tested every four hours.
3.5.4 Application of paint. The paint shall be applied to thoroughly dried surfaces within 24 hours after pretreatment to prevent contamination or rusting. Should 24 hours be exceeded, the applicator shall maintain OQE to determine if the substrate is suitable for coating. Use the manufacturer's technical data sheets for paint application of metal-rich coatings. The dried surface shall not show any corrosion or soiling prior to painting and be meticulously cleaned (see 3.3). The temperature of the metal surface and the application environment shall be controlled to eliminate blistering, poor adhesion or other film irregularities.
3.5.5 Paint thickness. For all tests requiring painted test specimens/coupons, the dry film thickness (see
4.7.6.1) on all surfaces shall be in accordance with MIL-DTL-53072 or as specified for the end item. When the paint thickness is not covered in the end item specification, the drawing, or paint specification requirement, the precedence shall be in the order cited in the contract.
3.5.6 Paint adhesion (all methods and types). The CARC or non-CARC painted items or specimens /
coupons shall show the following satisfactory paint adhesion when tested as in 4.7.6.2 and 4.7.6.3.
3.5.6.1 CARC painted items. The painted items, evaluated by using ASTM D3359 method B, shall have a minimum rating of 4B at 2 mm spacing. Removal of topcoat or topcoat-primer-pretreatment coating from any individual cross-hatch test on the unit with a rating of less than 4B constitutes failure of this
test (see 4.7.6.2).
3.5.6.2 Non-CARC painted items. Unless contraindicated by contract, coating system or engineering design when tested in accordance with ASTM D3359 method B, unsatisfactory adhesion shall be indicated by exposure of primer, bare metal, or underlying pretreatment by any of the following conditions:
(a) Any exposed area exceeding 1/8 inch average diameter.
(b) More than one exposed area exceeding 1/16 inch average diameter. (c) More than five exposed areas less than 1/16 inch diameter.
3.5.7 Accelerated corrosion resistance (all types). After pretreatment and primer (or paint for single coat systems) application, the specimens/coupons shall be subjected to the accelerated corrosion test as in
4.7.7, 4.7.7.1, 4.7.7.2 and 4.7.7.3 for the required number of hours/cycles specified. Specimens/coupons shall show no blistering or loss of adhesion of the paint from the scribe mark (for steel, a rating of 6, for aluminum, a rating of 8, ASTM D1654 method A). Blisters shall cover no more than 5% of the exposed
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