MIL-STD-193L
acceptable to the cognizant Government quality assurance representative. The test locations shall be routinely varied among the following:
a. Directly adjacent to a weld.
b. On or directly adjacent to a machine cut or sheared edge.
c. Any mechanically formed surface where lubricants are used. d. Paint touch-up areas.
5.8.1.1 Scribe tape test procedure. The following test procedure shall be followed for the scribe tape test (all dimensions are approximate):
a. Scribe four 1-inch lines completely through the paint finish, 1/16 to 3/32-inch apart.
b. Scribe another four 1-inch lines, 1/16 to 3/32-inch apart, and 90 degrees to the first set of lines. The resulting pattern shall be nine 1/16 to 3/32-inch squares.
c. Press a length of A-A-884, A-A-1830 or any commercially available tape with a minimum adhesion rating of 45 ounces per inch of width firmly over the scribed pattern rubbing out all air pockets.
d. Wait 10 seconds minimum. Grasp a free end of the tape and at a rapid speed strip it from the painted surface by pulling the tape back upon itself at 180 degrees.
The removal of two or more squares of topcoat, topcoat primer or topcoat primer- pretreatment coating shall be cause for rejection. Removal of overspray does not constitute test failure.
e. Upon completion of the adhesion test, the scribe marks shall be feathered into the adjacent area and touched-up per MIL-C-53072.
5.8.2 Paint film thickness. Test methods to measure paint film thickness shall be per MIL-C-53072. Dry film thickness of primers and topcoats shall be within limits specified in table III. The test gage shall be capable of being calibrated to known standards. Sufficient measurements shall be made to ensure that sufficient film has been applied irrespective of part configuration. Wet films shall be checked with a wet film gage. Total dry film thickness on flat, accessible areas shall not exceed 5 mils and 75 percent (%) of the surface area of each test unit shall meet the requirements of table III.
5.8.3 Corrosion resistance. The corrosion resistance for all but electrodeposited cathodic primers shall be verified in accordance with the salt spray test method of ASTM B117 (5% salt). The test shall be run for 336 hours on parts or the standard test panels specified in ASTM B117 cross scribed to the base metal. Evaluation shall be in accordance with ASTM D610 (No. 8)
with no blisters greater than 1.0 mm diameter. Rust creeping from the scribe line shall not
exceed one-eighth inch. Cathodic electrodeposited primers shall be subjected to a 1000 hour salt spray test in accordance with ASTM B117 (5% salt). Test panels shall be cross scribed to the base metal. Test panels shall show no more than a trace of rusting (ASTM D610, No. 8) and no blister larger than one millimeter in diameter. The cross scribe area shall not exceed 1/8 inch
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