MIL-PRF-44103D
4.4.7 Stiffness at low temperature test (classes 1 and 2). Stiffness test specimens shall be cut
and conditioned as specified in 4.4.6. The weight shall then be removed. The plate/specimen
assembly and the test instrument shall then be subjected to a temperature of minus 20o + 5oF
for not less than 1 hour and then tested at that temperature as specified in ASTM-D-747. The
load scale reading shall be taken only at a 20-degree angular deflection for each specimen.
4.4.8 Stiffness after heat aging test (classes 1 & 2). A sample of the cloth to be tested shall
be cut to measure 8 inches by 8 inches. The sample shall be hung vertically in a well
ventilated oven at a temperature of 200° + 5o F for 120 hours. The sample shall not be laid
flat in the oven. The sample shall be removed from the oven and placed between glass plates
with the dimensions stipulated in 4.4.6. A 20-pound weight shall be placed on the top plate
for 4 hours at Standard Conditions. The sample shall then be removed from the glass plates
and specimens shall be cut as specified in 4.4.6. Stiffness shall then be determined as
specified in ASTM-D-747. The load scale reading shall be taken only at a 20-degree angular
deflection for each specimen.
4.4.9 Stiffness at 70°F test (classes 3 and 4). TAPPI Method T-451, Preferred Procedure (1),
warp direction only.
4.4.10 Stiffness at 70°F test after accelerated weathering (classes 3 and 4). Test specimens
shall be exposed to the accelerated weathering test specified in 4.4.2 and tested for stiffness as
specified in 4.4.9.
4.4.11 Stiffness at -20°F (classes 3 and 4). TAPPI Method T-451, Preferred Procedure (1),
warp direction only, except that the test shall be performed at -20°F + 5°F after specimens
and equipment have been conditioned at this temperature for a minimum of 4 hours before
testing. Test shall be conducted in still air.
4.4.12 Stiffness at -20°F after oven aging (classes 3 and 4). Test specimens shall be exposed
in a circulating air oven at 180°F + 2°F for 100 hours, withdrawn from the oven and brought
to equilibrium under standard conditions prior to testing. The conditioned sample shall then
be tested for stiffness at -20°F as specified in 4.4.11.
4.4.13 Matching. The color and appearance of the face side and the back side of the cloth
shall match the standard sample or color number of FED-STD-595 when viewed under
filtered tungsten lamps that approximate artificial daylight and that have a correlated color
temperature of 7500 + 200oK, with illumination of 100 + 20 foot candles, and shall be a good
match to the standard sample or color number of FED-STD-595 under incandescent lamplight
at 2300 + 200oK.
4.4.14 Spectral reflectance measurements in the visible/near infrared. Spectral reflectance
data for class 1 Camouflage Green 483 and class 2 Desert Tan 459 shall be obtained from 600
to 860 nanometers (nm) and 700 to 860 nm respectively, at 20 nm intervals on a
spectrophotometer relative to a barium sulfate standard, the preferred white reference
standard. Other white reference materials may be used, provided they are calibrated to
absolute white; e.g., magnesium oxide, or vitrolite tiles. The spectral band width at 860 nm
shall be less than 26 nm. Reflectance measurements shall be made by either the
monochromatic or polychromatic mode of operation. When the polychromatic mode is used,
the spectrophotometer shall operate with the specimen diffusely illuminated with the full
emission of a continuous source that simulates in the visible spectrum either CIE Source A or
CIE Source D65. The specimen shall be measured as a single layer backed with two layers of
the same fabric and shade. Readings shall be taken on a minimum of two different areas, and
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