MIL-HDBK-1110
paint tanks may contain significant amounts of water or another
batch of paint. Incompletely emptied bead tanks may contain
beads of another type. Paint and bead samples should be taken
from drums or sacks to determine whether the supplier's material
meets all requirements. Excessive mixing of latex marking paints
should be avoided prior to testing, because their wetting agents
cause them to froth when heavily mixed, and this may result in
testing errors. Excessive stirring of beads may cause smaller or
lighter density beads to migrate to the bottom of the container.
Full sampling and inspection procedures are presented in Method
1031 of FED-STD-141.
c) Procedure 3: Percent by Weight of Paint Total
Solids and Pigment. These tests are run to provide information
on the paint composition and a quick check for its conformance to
specification. These tests are done with the same sample using
ASTM D 2369, Volatile Content of Coatings and ASTM D 3723,
Pigment Content of Water-Emulsion Paints by Low-Temperature
Ashing. By using the relationships percent total solids equals
percent binder plus percent pigment and percent total solids
equals 100 minus percent volatile, results of the two referenced
test procedures can provide data on any of these components
(e.g., solvent, binder, pigment, and total solids). Testing
should be done in triplicate to indicate repeatability. The
percent by weight of total solids (or the percent volatile) of
latex paints is determined by measuring the loss of weight after
the solvent has been evaporated off by heating the sample at 110
degrees C for 2 hours. The percent by weight of pigment is
determined by measuring the weight after further heating of the
samples for 1 hour at 450 degrees C to burn up the organic
binder.
d) Procedure 4: Specific Gravity of Paints. In ASTM
D 1475, Density of Paint, Varnish, Lacquer, and Related Products,
a metal cup of precisely selected volume is weighed first empty
and then filled with paint until it is forced out a hole in the
cap. The additional weight is a direct measure of specific
gravity.
e) Procedure 5: Paint Binder Identification. ASTM D
2621, Infrared Identification of Vehicle Solids From Solvent-
Reducible Paints can readily identify the generic type of marking
paints as 100 percent acrylic. Only a small sample of the wet or
dry (e.g., 1 square inch) paint is necessary.
f) Procedure 6: Specific Gravity of Beads. The
specific gravity of beads can easily be determined by field
personnel with access to an inexpensive balance following the
procedure of par. 4.3.5 of TT-B-1325. A sample of dried and
weighed beads (about 60 g) is placed in a glass graduated
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