TT-C-490F
4.8.6 Adhesion. Prepare three (3) steel and three (3) aluminum test specimens/coupons as specified in
4.8.2 and 4.8.4. Air dry the specimens/coupons for seven (7) days. Perform adhesion testing as specified in ASTM D3359, method B and examine for compliance with 3.6.2.
4.8.7 Flexibility. Prepare a steel and aluminum test specimen/coupon as specified in 4.8.2 and 4.8.4. Air dry the specimens/coupons for seven (7) days. Bend the coated specimens/coupons over a 1 inch mandrel. Examine the coating for cracks over the area of the bend for compliance with 3.6.3.
4.8.8 Water resistance. Prepare a steel and aluminum test specimen/coupon as specified in 4.8.2 and
4.8.4. Air dry the specimens/coupons for seven (7) days. Coat all exposed unpainted metal surfaces with wax or suitable protective coating and immerse in deionized water at 25 ± 1 °C (77 ± 2 °F) for 168 hours. Specimens/coupons shall be immersed at a minimum depth of 50%. At the end of the test period, remove and examine for compliance with 3.6.4.
4.8.9 Hydrocarbon fluid resistance. Prepare a steel and aluminum test specimen/coupon as specified in
4.8.2 and 4.8.4. Air dry the specimen/coupon for 168 hours and then immerse for 168 hours in a hydrocarbon fluid conforming to JP8 at 25 ± 1 °C (77 ± 2 °F). Specimens/coupons shall be immersed at a minimum depth of 50%. At the end of the test period, remove and examine for compliance with 3.6.5.
4.8.10 Corrosion testing. Prepare ten (10) steel and ten (10) aluminum pretreated and primed 4 x 6 inch specimens/coupons as specified in 4.8.2 and 4.8.4. Five (5) each of the steel and aluminum prepared specimens/coupons shall be exposed to the salt spray resistance and cyclic corrosion resistance. Allow to air dry for seven (7) days. Coat the edges and uncoated metal surfaces with suitable coating. For pretreatments that qualified to only class A or B, use only steel or aluminum specimens/coupons as appropriate.
4.8.10.1 Salt spray resistance. Take five (5) of the steel specimens/coupons and the five (5) aluminum specimens/coupons from 4.8.10 and make an "X" scribe through the primer. Expose these for the number of hours as specified in table II in accordance with ASTM B117. Upon removal, wash the specimens/coupons gently in warm running water until free from any visible salt deposits and examine immediately for compliance with 3.6.6.1. When visual examination is indeterminate, the specimens/coupons shall be scraped with a 2 inch wide metal putty knife or strip primer and inspect for rust, pitting or corrosion not evident with paint present. Nonconformance shall constitute failure of this test.
4.8.10.2 Cyclic corrosion resistance. Take remaining five (5) steel and aluminum specimens/coupons from 4.8.10 and make an "X" scribe through the primer. Expose the specimens/coupons to accelerated cyclic corrosion for the number of cycles as specified in table II in accordance with GMW 14872. Upon removal, rinse specimens/coupons until visible salt deposits are removed. Examine immediately for compliance with 3.6.6.2. When visual examination is indeterminate, the specimens/coupons shall be scraped with a 2 inch wide metal putty knife or strip primer and inspect for rust, pitting or corrosion not evident with paint present. Nonconformance shall constitute failure of this test.
4.8.11 Hydrogen Embrittlement. Apply pretreatment to three (3) type 1e coupons according to manufacturer's recommended cleaning and application procedures. The notch should be masked for any mechanical cleaning procedures. Coupons shall be tested according to A3 of ASTM F519. If product
is found to contribute to hydrogen embrittlement, a statement to that effect will be required on
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