MIL-PRF-20696F
4.4.2 Accelerated weathering procedure. One specimen, 8 by 6 inches minimum, with the
short dimension warpwise and one specimen, 8 by 6 inches, minimum, with the short
dimension filling wise shall be subjected to the procedure specified in Method 5804 of FED-
STD-191. The procedure shall be performed with the face side exposed. The exposure times
shall be as follows:
Types I, II and IV; class 2 - 150 hours for all colors.
Types I, II and IV; classes 1 and 3 - 150 hours for olive green and black only, all other
colors - 50 hours.
Type III, class 5 - 150 hours for all colors.
After exposure, the specimens shall be removed and allowed to condition for at least 24
hours.
NOTE: Equipment which operates at one revolution in two hours. may be used. However,
the one revolution per minute shall be the standard procedure in the event of dispute.
Laboratory reports shall state the procedure used.
4.4.3 Stiffness
4.4.3.1. TAPPI Method T-451, Preferred Procedure (1).
4.4.3.2 The stiffness test shall be conducted as specified in 4.4.3.1 except that the apparatus
and test specimens shall be conditioned at the specified temperature for a minimum of 4
hours before testing and the test shall be performed in a still atmosphere at that temperature.
4.4.4 Adhesion of coating. ASTM-D-751, Adhesion of Coating with 2 inch wide reinforced
coating adhesion specimens, cyanoacrylate (solventless) adhesive, and pulling clamp speed of
5 mm/s. The test shall be performed on the coated side (if one side coated) or face to back (if
two sides coated) of the cloth. Testing shall be performed in the warp direction.
4.4.5 Blocking. ASTM D-751, Determination of Blocking Resistance of Fabrics Coated with
Rubber or Plastics at Elevated Temperatures, except that the specimens shall be exposed at an
oven temperature of 180°F + 2°F for 30 minutes.
4.4.6 Hydrostatic resistance.
4.4.6.1 ASTM D-751, Hydrostatic Resistance Procedure B (Pressure Application by a Rising
Column of Water), Procedure 2 with the hydrostatic head fixed at 50 centimeters and applied
to the test specimen for 10 minutes. The back side of the cloth shall contact the water. The
report shall only include "measurement of the appearance of water drops". Leakage of any
specimen shall be considered a test failure. Leakage is defined as the appearance of water at
three or more different places within the 4-1/2 inch diameter test area.
4.4.6.2 A new specimen, 10 by 10 inches, shall be abraded by means of a 2-inch square piece
of grade 1/0 garnet paper which shall be uniformly loaded with an 8.0 + 0.1 ounce weight.
The specimen shall be abraded on the face by moving the weighted garnet paper filling-wise
five times in each direction. The specimen shall then be turned over and abraded on the back
by moving the weighted garnet paper warp-wise five times in each direction. The abraded 2-
inch square area shall then be placed face up across the center line of the clamping head so
that the center of the abraded area will coincide with the center of the exposed part of the
specimen. Hydrostatic resistance shall then be determined as specified in 4.4.6.1.
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