Technical data
c. If it is required to mix batches smaller than the full unit
size, strictly maintain the proportions of vehicle and
pigment specified by the manufacturer.
NOTE
Proportions customarily are given by weight. If
mixing less than a full kit, it can be done by using
the volume of the vehicle and the weight of the
zinc pigment. Determine the fraction of the total
kit volume of the vehicle being used and multiply
the total weight of the zinc pigment in the kit by
this fraction, and weigh out that amount of zinc
pigment and mix with the volume of vehicle
being used. An accurate scale is required that will
weigh up to 2.6 kilograms to the nearest 0.1 of a
gram. A scale which meets these requirements is
the Triple Beam 760W Balance made by Paul N.
Gardner Co., Inc.; 316 NE First St.; Pompano
Beach FL 33060.
d. Stir until zinc pigment is thoroughly wetted and the
mixture is free of lumps. If small lumps persist, strain
the mixture through a 30 mesh wire screen or through
double or triple thickness of cheesecloth before using.
e. When application is by brush, stir moderately and often
to maintain a homogeneous mixture throughout appli-
cation.
6.12.10.4 Thinning.
Use A-A-59282 (NSN-6810-00-127-4532) ethyl
alcohol only where no fire hazards exist. Within
enclosed areas and the missile silos use the
A-A-59106 ethylene glycol monoethyl ether.
Package viscosity is generally appropriate for brush applica-
tion. Adjust the viscosity for spraying by thinning in accor-
dance with the manufacturer’s instructions using the follow-
ing:
• The proprietary thinner(s) called out by the manufac-
turer.
• Either A-A-59282 ethyl alcohol, (NSN-6810-00-127-
4532) or A-A-59106 ethylene glycol monoethyl
ether.
6.12.10.5 Application. HVLP spray application is the
preferred method; however, the material can be applied by
brush. Airless spraying methods are not recommended, as the
higher pressure involved (1200-2200 PSI) can result in the
rapid packing of the zinc pigment at valves and orifices.
6.12.10.6 Drying Time. On dry surfaces at 75° F, it is
tack free in 30 min. and fully cured in 4 hours. On wet
surfaces at 75° F, it is tack free in 1 hour and fully cured in
6 hours.
NOTE
• Materials can vary to some extent under the
controlling MIL-P-38336/SAE AMS-P-
38336. The specification requires inclusion of
mixing, thinning, application and curing in-
structions in the package. Where the manufac-
turer’s application instructions differ apprecia-
bly from these general supplementary
instructions, the manufacturer’s instructions
shall apply.
• It is difficult to impossible to measure viscos-
ity of inorganic zinc primer using the standard
authorized measuring devices; therefore, it
will not be done. Use the proportions of
thinner recommended by the manufacturer,
adjusting further in small degrees to suit
special conditions using the painters judg-
ment. Just prior to spraying, wet or damp
surfaces shall be wiped clear of moisture films
and, (where possible), then solvent wiped with
clean cloths wetted with A-A-59282 ethyl
alcohol (NSN 6810-00-127-4532) or TT-I-735
isopropyl alcohol. When using spraying tech-
nique, adjust material tank pressure as recom-
mended by the manufacturer or, in absence of
this information, to 12-15 PSI, or less.
6.12.11 Primer Coating For Steel Surfaces, Specifi-
cation MIL-PRF-26915. This specification covers two
types of primer, each with two different classes for use on
steel surfaces. Both types and classes are compatible with
MIL-PRF-85285 polyurethane topcoat material.
6.12.11.1 Characteristics. Traditionally, this has been
an organic zinc dust pigmented primer used for galvanic
protection of steel surfaces on ground support equipment.
This primer is furnished in two types and two classes: Type I,
non-water reducible, Type II (DEFT Corp., PN 44-GY-16,
CAGE 33461) water reducible, Class A maximum VOC
content of 340 g/L (2.5 lbs/gal), and Class B maximum VOC
content of 250 g/L (2.1 lbs/gal). This primer may come in
two, three, or four-component kits.
6.12.11.2 Use. The primer is used to provide galvanic
protection for steel ground support equipment surfaces. Use
two coats (4-6 mils dry film thickness) for severe exposure
such as on steel that is normally subjected to outside
exposure, condensing moisture, or corrosive atmospheres. If
color or finish texture is important, overcoat with one coat of
MIL-PRF-85285, Type I, II or III polyurethane.
6.12.11.3 Mixing. Mix in accordance with manufactur-
er’s instructions. To prevent settling of the pigment, continu-
ous agitation of the coating is necessary during application.
TO 1-1-8
6-17