MIL-DTL-24631A(SH)
4.5.3.3 Formula 186. The whiteness difference of the dry test paint
from color 17886 of FED-STD-595 shall be determined in accordance with
ASTM D 1729. Color deviation shall be in accordance with the requirements of
3.4.1 and the appropriate specification sheet.
4.5.3.4 Alternative color measuring equipment. Manufacturers can
qualify alternative color measuring equipment to Naval Sea Systems Command
(NAVSEA) or the General Services Administration (GSA) by demonstrating that
the particular instrumentation to be used measures the green color parameter
with the accuracy required in 4.5.3.1. The manufacturer shall demonstrate
that the alternate instrumentation can provide green color parameters that
result in the colors defined in 3.4.
4.5.4
Volatile solvent constituent content.
4.5.4.1 Solvent constituent content. Solvent constituent content shall
be determined in accordance with Methods 7356 and 7360 of FED-STD-141.
Solvent fractions shall be identified in accordance with ASTM E 1252. Test
results shall be reported as % by weight of the total solvent content. The
test results for each solvent shall be in accordance with the requirement in
3.4.2 and the appropriate specification sheet (see 6.5).
4.5.4.2 VOC. VOC tests shall be conducted on mixed paint prepared for
application in accordance with 4.5.4. The VOC test shall be conducted in
accordance with 40 CFR CH.1, part 60, appendix A, (EPA) method 24 and test
results shall be in accordance with the requirements of 3.4.2 and the
appropriate specification sheet (see 6.5).
4.5.5
Color fastness.
4.5.5.1 Formulas 184, 185 and 186. Color fastness shall be determined
in a xenon or equivalent weathering device operated in accordance with D 822.
Three test panels of appropriate size for equipment shall be prepared as
specified in 4.5.3. Dry color measurements shall be performed in the normal
way. Wetted green reflectance (RW) of the test panels shall be measured in
accordance with 4.5.3 before testing. Record dry and wetted green
reflectances. After 500 hours exposure in the weather device, remeasure dry
and wetted green (RW) reflectance in accordance with 4.5.3. Determine change
in dry and wetted green (RW) reflectance for each test panel. Average both
the dry and wetted green (RW) reflectance reflectances. The average change in
reflectances shall be in accordance with the requirements of 3.4.3
4.5.5.2 Formula 187. Color fastness shall be determined in accordance
with 4.5.5.1, except that an ASTM G 53 ultraviolet weather device shall be
used. The ASTM G 53 device shall be operated as follows:
(a)
Set device parameter controls to provide alternating periods
of 6 hours darkness at 100% humidity and 6 hours of UVb
radiation.
(b)
Device UV bulbs shall have average wavelength of 313
nanometers (nm).
(c)
Temperature controls shall be capable of maintaining the
device a nominal 23 C (73 F) during the dark portion of a
cycle and a nominal 52 C (125 F) during the UV lighted
portion of a cycle.
(d)
Dry tristimulus reflectance values and wetted green
reflectance of the test panels shall be measured in
accordance with 4.5.3 before testing. Record the dry
tristimulus reflectance and wetted green reflectances.
After 500 hours exposure in the weather device, remeasure
dry tristimulus reflectance values and wetted green
reflectance in accordance with 4.5.3. Calculate color
parameters, L, a and b, and the color change terms Delta ( )
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