MIL-DTL-53039E
4.6.5 Hexavalent chromium. Determine the presence or absence of hexavalent chromium by
either of the following chemical reagent screening techniques.
(a) Weigh approximately 250 mg of pigment into a small glass test tube. Add 5 ml of 25
percent aqueous KOH and shake vigorously for 1-2 minutes. Decant a one ml aliquot into a
plastic micro-centrifuge tube and centrifuge for five (5) minutes at 17000 rpm, balancing the
centrifuge with a tube containing one ml of the KOH solution. The resulting supernatant liquid
shall be nearly colorless. Use the tube containing the KOH solution as a reference. A distinct
yellow color indicates the presence of hexavalent chromium and therefore shall constitute failure
of the test requirement.
(b) Weigh approximately 50 mg of pigment into a small glass test tube. Add 5ml of 10
percent aqueous H2SO4 and shake vigorously for 1-2 minutes. Decant a one ml aliquot into a
plastic micro-centrifuge tube and centrifuge for five (5) minutes at 17,000 rpm, balancing the
centrifuge with a second tube containing one ml of the H2SO4 solution. The solution in the
second tube shall act as the test "blank". Immerse a chromate ion (CrO42-) test strip into the
supernatant from each tube. Shake off the excess liquid and after approximately one minute
compare the color change in the reaction zone of the strips to the color scale (concentration
levels) provided by the manufacturer. The appearance of a purple/violet color from the "sample"
strip is indicative of hexavalent chrome and therefore shall constitute failure of the test
requirement. If a color change is apparent from the "blank" strip rerun the test using fresh,
chromium-free reagents. The appearance of a pronounced color change is indicative of
hexavalent chrome and therefore shall constitute failure of the test requirement.
4.6.6 Lead content. Determine the presence or absence of lead by weighing 50 mg of pigment
into a small glass test tube. Add 5 ml of dilute HNO3 and shake vigorously for 1-2 minutes.
Decant a one ml aliquot into a plastic micro centrifuge tube and centrifuge for five (5) minutes at
17,000 rpm, balancing the centrifuge with a second tube containing one ml of the dilute HNO3
solution. The solution in the second tube shall act as the test "blank". Immerse a lead ion test
strip into the supernatant from each tube. Shake off the excess liquid and after approximately one
minute compare the color change in the reaction zone of the strips to the color scale (concentration
levels) provided by the manufacturer. If a color change is apparent from the "blank" strip rerun
the test using fresh, lead-free reagents. Confirmation of the exact lead concentration in the
coating's solids shall be quantified using ASTM D3335. Nonconformance to the table VII
requirements shall constitute failure of this test.
4.6.6.1 Antimony, arsenic, beryllium, cadmium, cyanide, manganese, mercury, nickel and
selenium. Manufacturers need to review applicable environmental and safety regulations and
comply with material shipment requirements (see 6.2). The SDS needs to include a notarized
statement that verifies that the composition of the material (coating formulation) is free of the
antimony, arsenic, beryllium, cadmium, cyanide, manganese, mercury, nickel, selenium and their
compounds.
4.6.7 Nonvolatile vehicle. Centrifuge a 1:1 mixture of methyl isobutyl ketone and paint at
12,000 rpm for 10 minutes. Evaporate a film of the vehicle on a sodium chloride plate at 105 °C
(221 °F) for 5 minutes. Scan the infrared spectrum from 2.5 to 15 micrometers. Check for
compliance with 3.4.2.
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