TT-P-28H
4.5.2 Test methods. Tests shall be conducted in accordance with the FED-STD-141, ASTM applicable methods or as required by this specification. The issue of the test method shall be as required by section 2. The right is reserved to make any additional tests deemed necessary to determine that the paint meets the requirements of this specification. Failure to pass any test and non-compliance to the requirements of section 3 shall be cause for consideration to reject the lot.
4.5.3 Nonvolatile (total solids) content (type I). Place a portion of the thoroughly mixed sample in a dropping bottle and weigh to the nearest 0.1 milligram (mg). Weigh a 60 millimeter (mm) diameter aluminum dish to the nearest
0.1 mg. Transfer a small sample that does not exceed 0.3 gram (g) to the dish. Determine its exact weight by loss in weight of the bottle. Dissolve the sample in 2 milliliters (ml) American Chemical Society (A.C.S.) reagent grade
toluene and dry in a gravity convection oven at 105 °C (221 °F) for 30 minutes. Upon cooling, reweigh the dish to the nearest 0.1 mg. From the weight of the residue in the dish and the weight of the sample taken, calculate the
percent nonvolatile (total solid) as required. Nonvolatile vehicle (total solids) shall be in accordance with the
requirements of Table I.
4.5.4 Silica content of vehicle. From a stoppered bottle or weighing pipette, weigh by difference (to the nearest 0.1 mg) about 3 grams of vehicle (V1) isolated by ASTM D2698 into a previously ignited and weighed 3-inch porcelain evaporating dish (V2). Dry at 105 °C (221 °F), in an oven for 3 hours. Place the dried sample in a cold muffle furnace and gradually increase the temperature over a period of 3 hours to 538 °C (1000 °F) then maintain this temperature for an additional hour. After cooling in a desiccator, weigh the dish and contents (V3). Calculate weight of ash (silica) (V3-V2). Calculate the percent of silica as follows:
Percent silica by weight of vehicle
= Weight of ash (V3-V2) X 100
Weight of sample (V1) X nonvolatile vehicle fraction
Silica content shall be in accordance with the requirements of Table I.
4.5.5 VOC (volatile organic content). When tested in accordance with 40 CFR CH. 1, Part 60, Appendix A, (U. S. EPA) Method 24, the VOC in the paint shall be in accordance with the requirements of 3.2.3.
4.5.6 Drying time.
4.5.6.1 Air drying, type I. Draw down a film of the paint on a glass panel or Leneta chart using a 20.3-micron (0.0008-inch) applicator (50 micron [0.002 inch] gap clearance) and determine air drying time at nominal laboratory conditions in accordance with method 4061 of FED-STD-141. Drying time shall be in accordance with the requirements of Table I.
4.5.6.2 Full hardness, type I. Determine full hardness by spraying a film of paint to a dry film thickness of 20.3 micron (0.0008 inch) to 30.5 micron (0.0012 inch) on a steel panel that has been solvent cleaned with the Aliphatic Naptha-Ethylene Glycol Monoethyl ether mixture in accordance with method 2011 of FED-STD-141. Air dry 30 minutes and then bake at 204±2 °C (400±5 °F) for 1 hour. Determine compliance with full hardness requirement of Table I. The film shall be considered to have reached full hardness when it is very difficult to remove with a knife blade in accordance with Method 6304.2 of FED-STD-141.
4.5.6.3 Full hardness (type II). Full hardness and cure of Type II powder coatings when baked at 204 °C (400 °F)
shall be no longer than 20 minutes.
4.5.7 Condition in container. Determine package condition for conformance testing in accordance with method
3011 of FED-STD-141. Package condition shall be in accordance with the requirements of 3.4.1. The unopened can shall show no evidence of gas build-up, such as bulging of can. Do not agitate the can. Open the container, but do not stir. Evaluate pigment settling or caking by proceeding as in method 3011 of FED-STD-141. Reseal and
agitate the can for 3 minutes on a paint shaker. On re-examination of the contents, the disclosure of any gel bodies,
undispersed pigment, floating or undispersed settled pigment indicates unsatisfactory settling properties. Contents shall be in accordance with the requirements of 3.4.1.
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