MIL-DTL-12276E(MR)
panel. The film shall be examined on the convex surface for compliance with 3.10. A strip
of transparent, pressure-sensitive adhesive cellophane tape conforming to A-A-113 shall be
pressed down on the convex area of the impacted surface and then stripped off. None of the
coating shall be lifted by the adhesive tape.
4.3.11 Thermoplasticity. Two test panels, free from defects, 3 x 6 x 0.026 inches in size,
and two panels 1 x 2.5 x 0.026 inches in size for each baking schedule specified in 4.3.1
shall be used. Panels shall be prepared and coated as specified in 4.3.1. The edges of the 1 x
2.5 x 0.026 inch coated panels shall be broken down to the bare metal so that all burrs and
varnish beads are completely removed. The test panels shall be placed film to film in an
oven at 600o ± 5o F. These panels, with the smaller panel uppermost in each case, shall rest
on a smooth flat steel plate previously brought to oven temperature. The steel plate shall be
a minimum of 4 x 6 x 1/4 inches in size. To assure that the weights and steel plates have
been brought to oven temperature, they shall be placed in the oven maintained at 600o ± 5o F
for one hour prior to use. As soon as the test panels and plates have been placed in the oven,
a 2-kilogram weight, previously brought to oven temperature, shall be placed on each of the
smaller panels. Keep the panels in oven maintained at 600o ± 5o F for 15 minutes. Remove
the weights from the panels and immediately reverse the position of the panels so that the
larger panels are uppermost. The smaller panels shall immediately fall away from the larger
panels.
4.3.12 Viscosity. The viscosity shall be determined by using a suitable Viscosimeter with
an appropriate spindle at a temperature of 70o ± 2o F.
4.3.13 Shelf life. A tall, wide mouth 8 oz. container shall be filled with the varnish to
within 1/8 inch of the top. Record the viscosity, then place the covered container in the oven
at 140o ± 5o F for 90 hours. Remove the container, allow to cool and again determine the
viscosity.
Percent change in viscosity = (V2 V1) x 100
V1
Where; V1 = original viscosity
V2 = viscosity after 90 hours at 140o ± 5o F.
4.3.13.1 Extended shelf life test. A one quart container of the subject material shall be
stirred/shaken as required by the manufacturer. The viscosity shall then be measured at 70o
± 2o F and recorded. This container shall then be sealed and stored on a shelf in a cabinet
out of direct light and heat sources at room temperature for a period of one year. At the end
of that period of time, the container shall then be stirred/shaken as recommended by the
manufacturer and then its viscosity measured at 70o ± 2o F and its viscosity compared to the
first measurement one year earlier. The newest viscosity reading shall not be more than 15%
greater than the first reading.
4.4 Rejection.
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