Technical data

6.12.3.1 Characteristics. This is a two-component,
lead free, water-reducible corrosion inhibiting, epoxy primer
formulated to meet most local environmental pollution regu-
lations. This primer is available in two different types each
with three different classes.
Type I Standard pigments (yellow).
Type II Low infrared reflective pigments (dark
green).
Class C1 Barium chromate based corrosion inhibi-
tors.
Class C2 Strontium chromate based corrosion in-
hibitors
Class N Non-chromate based corrosion inhibitors.
Class N shall not be substituted for Class C1
or Class C2, unless authorization is given by
the procuring activity or engineering author-
ity for the system or item on which the
primer is used.
6.12.3.2 Uses. As a primer for MIL-PRF-85285 poly-
urethane topcoat for aircraft and a stand alone primer on
interior surfaces of aircraft and components.
6.12.3.3 Mixing. See manufacturer’s mixing instruc-
tions, as different manufacturers may have different mixing
ratios and methods.
6.12.3.4 Thinning. Thin with water per the manufactur-
er’s instructions as each manufacturer may have different
thinning ratios and methods. Application viscosity will be
approximately 14 seconds in a No. 4 Ford Cup (20 seconds in
a No. 2 Zahn Cup). Allow the mixed and thinned primer to
stand 30 minutes prior to use.
NOTE
The volume of some primers may increase by
250% when properly thinned with water.
6.12.3.5 Application. After thoroughly cleaning, sur-
face treating, and solvent wiping the surface to be primed per
Chapter 3 and purging spraying equipment lines with a
mixture of 25% TT-I-735 isopropanol alcohol and 75% water,
apply the primer to a dry film thickness of 0.6 to 1.8 mils; see
Table 5-2 (2.5 to 3.8 mils wet film). Allow a minimum of two
hours air dry at 75° F or higher and 50% or less relative
humidity and four hours at lower temperatures and high
humidity to a maximum of eight hours before topcoating.
After eight hours, the primer shall be lightly scuff-sanded
with A-A-58054, Type I, Grade A abrasive mat, tack-ragged
and solvent wiped before topcoat application. Areas that are
not clean will not support the primer film, which will break
into droplets; like a water break test. If this happens, the
primer can be blotted up, the area wiped clean with a clean
cloth dampened with solvent per Table 3-2, and the primer
reapplied.
6.12.3.6 Drying Time. The times given here are for 75°
F at 50% relative humidity. Lower temperatures and higher
relative humidity will increase these drying times while
higher temperatures and lower relative humidity will decrease
these drying times. Tack free - 1 hour; Dry hard - 6 hours;
Full cure - 48 hours.
6.12.4 Primer Coating, Polyurethane, TT-P-2760.
TT-P-2760 is moderately toxic to eyes, skin, and
respiratory tract. Eye and skin protection re-
quired. Consult Bioenvironmental Engineering to
determine need for respiratory and ventilation
requirements.
6.12.4.1 Characteristics. This is a two component, low
VOC, solvent borne, highly flexible elastomeric polyurethane
primer. The maximum VOC content of the primer coating is
340 g/L (2.8 lbs/gal). It is available in two different types each
with two different classes.
Type I Standard pigments (yellow or light
brown).
Type II Low infrared reflective pigments (dark
green).
Class C Strontium chromate based corrosion in-
hibitors.
Class N Non-chromate based corrosion inhibitors.
NOTE
Class N shall not be substituted for Class C
unless authorization is given by the procuring
activity or engineering authority for the system or
item on which the primer is used.
6.12.4.2 Uses. As a primer for MIL-PRF-85285 poly-
urethane topcoat. It is a suitable alternate for MIL-PRF-
23377 and MIL-PRF-85582 primers and can be used as a
touch-up primer for both MIL-PRF-23377 and MIL-PRF-
85582 on exterior surfaces. Because of this primer’s flexibil-
ity, it is recommended for high impact areas such as leading
edge slats, and the entire exterior surface on large, flexible
cargo and bomber aircraft.
6.12.4.3 Mixing. Shake the base material (component A)
for five minutes on a paint shaker and stir the catalyst
(component B) with a wooden paddle prior to mixing. Pour
one volume of catalyst into one volume of base, and mix the
TO 1-1-8
6-8 Change 3