TT-P-1757B
4.6.5 Adhesion - wet tape. The primer coating shall be applied to test panels in accordance with 4.5 and 4.5.1 and topcoated in accordance with 4.5.2, with the exception that the topcoat shall be dried for 6 hours. The test panels shall then be immersed in distilled water at room temperature [25 ±3°C (77 ±5°F)] for 24 hours. Within sixty minutes after removal from the distilled water, the test panels shall be wiped dry with a soft cloth and tested in accordance with FED-STD-141, method 6301, with the exception the tape shall be pressed down using two passes of the rubber-covered roller.
4.6.6 Flexibility. Test panels for the flexibility tests shall be aluminum alloy 2024 conforming to QQ-A-25014 (0 temper), anodized in accordance with MIL-A-8625, type I, with approximate dimensions of 0.020 by 3.0 by 6.0 in. (0.5 by 76.2 by 152.4 millimeters (mm). The primer coating shall be applied to test panels in accordance with 4.5.1 and topcoated in accordance with 4.5.2, with the exception that the topcoat shall be air-dried for 30 minutes and then baked at 95° to 105°C (203° to 221°F) for 24 hours. The coated test panels shall then be bent over a 118 in. (3.2 mm) mandrel, in accordance with FED-STD-141, method 6221 for conformance to 3.5.4.
4.6.7 Lifting. The primer coating shall be applied to 6 separate test panels, in accordance with 4.5 and 4.5.1, reserving one panel for each of the following air-dry times: 10 minutes;
30 minutes; 1 hour; 6 hours; 16 hours; and 48 hours. At the end of each drying time, apply one coat of lacquer conforming to TT-L-32, type II, to a dry film thickness of 0.8 to 1 mil (20.3 to
25.4 mm). After the topcoat has air dried for 72 hours, examine for conformance to 3.5.5.
4.6.8 Resistance properties.
4.6.8.1 Hydrocarbon resistance.
4.6.8.1.1 Primer coating. The primer coating shall be applied to test panels in accordance with 4.5 and 4.5.1 and air dried for 48 hours. Immerse the test panels in fluid conforming to TT-S-735, type III, for four hours at room temperature [25 ±3°C (77 ±5°F)]. 24 hours after removal from the fluid, examine the coating for conformance to 3.6.1.1.
4.6.8.1.2 Primer coating and topcoat. The primer coating shall be applied to test panels in accordance with 4.5 and 4.5.1 and then topcoated in accordance with 4.5.2, with the exception that the test panels shall be air dried for 24 hours and then baked at 95° to 105°C (203° to 221°F) for two hours. The test panels shall then be immersed in fluid conforming to TT-S-735, type III,
maintained at room temperature [25 ±3°C (77 ±5°F)] for four hours. 24 hours after removal from the fluid, examine the coating for conformance to 3.6.1.2.
4.6.8.2 Hydrocarbon resistance - flexibility. The test panels used in 4.6.8.1.1 and 4.6.8.1.2 shall be bent 180° over a ½ in. (12.7 mm) mandrel, in accordance with FED-STD-141, method
6221, and examined for conformance to 3.6.1.3.
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