Technical data

cannot be raised, discard or set aside the wash primer being
used and mix and thin a new batch following the instructions
in Paragraph 6.12.5.3 and Paragraph 6.12.5.4.
NOTE
Isopropyl alcohol shall not be substituted for
ethyl alcohol in thinning wash primer as the
addition of water in the thinning process for low
humidity will cause the material to gel.
6.12.9.8.2 High-Humidity Application. Wash primer
will blush, resulting in a whitish color caused by moisture
condensation in the film and be easily scratched with a
fingernail when applied under high relative humidity and high
temperature conditions. When blushing is encountered, dis-
card or set aside the wash primer being used and mix and thin
a new batch following instructions in Paragraph 6.12.5.3 and
Paragraph 6.12.5.4.
6.12.9.9 Drying Time. Wash primer dries to handle
within a few minutes, but, allow it to dry for at least 60
minutes but no more than 4 hours, depending on local
temperatures and humidity conditions, before topcoating. For
best results, apply the subsequent primer coat as soon after
the wash primer is tack free because intercoat adhesion
begins to degrade slowly on aging indoors and rapidly when
exposed to the sun. Best intercoat adhesion will generally be
obtained after 1 to 2 hours drying under normal conditions.
The actual drying time required can be determined for local
conditions by applying wash primer to several test panels and
performing the wet tape test on a primer film over the wash
primer after various drying periods. This test should be done
prior to wash primer application to the end item.
NOTE
Do not apply primer on any wash primer when it
has dried for more than 4 hours. Remove aged
wash primer, thoroughly clean metal, and apply
new wash primer coating before applying a
primer.
6.12.9.10 Sanding of Wash Primer Coating. To ob-
tain the full gloss of exterior topcoat, lightly scuff sand with
dry 320 to 400 grit abrasive paper to remove over-spray and
smooth out nibs. Remove dust resulting from this operation
with a tack rag before applying the primer.
6.12.10 Primer, Coating, Inorganic, Zinc Dust Pig-
mented, Self-Curing, For Steel Surfaces, Specification
MIL-P-38336/SAE AMS-P-38336.
6.12.10.1 Characteristics. This is a ready-to-mix two-
component, inorganic zinc, corrosion inhibitive primer con-
sisting of a liquid inorganic vehicle and zinc dust pigment in
separate containers. It is intended for use on steel and
galvanized surfaces, above or below grade, that are subjected
to damp or wet environments, i.e., high humidity of 70% or
above, water condensate or splash, and marine or severe
weather environments. It has high resistance to hydrocarbon
solvents and withstands temperatures up to 750° F. It provides
galvanic protection to steel surfaces. Thorough cleaning is
required to remove rust, scale and oil from surfaces so the
primer can make intimate electrical contact with the steel.
6.12.10.2 Uses. The primer is for application directly to
steel surfaces with or without phosphoric acid treatment
(Reference TO 1-1-691) which have been roughened me-
chanically preferably by abrasive blasting. It may be applied
to damp, but not to wet surfaces, and may be used alone or
with a variety of proprietary items, applied in accordance
with vendor’s instructions. Inorganic zinc primer may appear
in versions requiring water as a diluent. Storage stability or
“Shelf Life” is one year in an unopened package. It is not for
use in direct contact with acids, alkalis or salts. MIL-P-
38336/SAE AMS-P-38336 inorganic zinc primer is the pre-
ferred primer for use in high humidity application.
6.12.10.3 Mixing.
Most inorganic primers contain flammable sol-
vents. In confined areas, proper respiratory pro-
tection must be worn. Contact the Base Safety
Office and the Bioenvironmental Engineer for
specific details.
The primer is supplied as a two component kit. The liquid
vehicle container holds an amount which when mixed with
the zinc dust pigment provides the specified volume of
primer. Mix the component materials in the proportions
furnished as follows:
a. Mix the vehicle portion thoroughly until all solids are in
suspension using hand paddles, mechanical devices or
any powered stirrers available.
b. Sift the zinc dust pigment slowly into the mixed vehicle
while stirring continually. Use either hand paddles or a
small powered stirrer. Do NOT use a powered shaker
type paint agitator to disperse zinc dust in the vehicle.
TO 1-1-8
6-16