MIL-DTL-757C
this composite sample. Both sub-samples shall be tested in accordance with the applicable test
methods of 4.4 to determine conformance with the requirements of granulation (see TABLE I),
material insoluble in ammonium acetate (see TABLE I), material soluble in ether (see TABLE I),
lead content (see TABLE I), nitrogen content (see TABLE I), and instantaneous flash point
(DSC) (see TABLE I). If either sub-sample fails to meet any of the test requirements, the lot
represented by the composite sample shall be rejected.
4.4 Methods of inspection. All tests described in this section shall be performed using
prescribed procedures.
4.4.1 Preparation of dry sample. Transfer a portion of the wet sample containing about
10 g of lead styphnate to a Buchner funnel containing a medium texture filter paper and apply
suction until sample is almost dry. While working behind a safety shield, spread the sample over
a watch glass. Dry the sample by placing the watch glass in a desiccator over drying agent for 24
hours at ambient temperature or in an oven no higher than 75ºC until constant weight is obtained
(this will take at least 2 hours). Use this dry sample for all determinations unless otherwise
specified.
4.4.2 Appearance. Take a portion of the well stirred wet sample from 4.3.3.1 and spread
over an area of approximately 4 cm2 on a glass microscope slide. Allow the sample to air dry.
Examine the material microscopically for impurities using magnification of 50x, under
illumination. Any sample containing visible impurities or foreign matter shall be rejected.
Retain the slide for the determination of crystal form (see 4.4.3) and crystal dimensions (see
4.4.4).
4.4.3 Crystal form. Using the slide prepared in 4.4.2, observe the crystalline form (shape)
under a microscope using a magnification of l00x under reflected light, and optionally, take a
photomicrograph at 50x magnification. Any sample containing crystal form with the longest
dimension greater than three times the next longest axis shall result in rejection of the batch.
4.4.4 Crystal dimensions. Using the slide prepared in 4.4.2, measure the longest
dimension of the larger crystals observed when scanning the field with the aid of a mechanical
stage. Use the most accurate means available to determine the longest crystal dimension.
Consider the longest dimension to be the distance between the most remote points of any one
crystal.
4.4.5 Granulation. Transfer about 30 g of the wet sample to a Buchner funnel and apply
suction for 2 to 3 minutes. Weigh out a 10 g portion of the damp sample and transfer it to a clean
three inch US Standard #100 Sieve which conforms to the requirements of ASTM E11 and
ASTM E323. Carefully examine the sieve to be sure it is free of foreign material. Place the sieve
in a porcelain evaporating dish which contains enough water to cover the wire screen of the sieve
to a depth of about one half inch. Shake the sieve for a few minutes in such a manner that the
lead styphnate is below the surface of the water and any material passing through the sieve is
caught in the evaporating dish. When most of the lead styphnate has passed through the sieve,
run a gentle stream of water through the sieve while brushing the residue gently with a soft
natural hair brush until all in the sample that will pass through the sieve has passed through it.
Behind a safety shield, visually examine the screen of the sieve for the presence of lead
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