MIL-PRF-25134C(USAF)
4.5.1 Preparation. A three-necked flask, fitted with stirrer, reflux condenser and dropping funnel
is charged with the solids (Wax, Wetting Agent, and Methyl Cellulose). The organic solvents are
then added to the solids already in the flask. While stirring, the formulation is brought to reflux
for a period of one hour. Use an appropriate size heating mantle to heat the flask. At the end of
the reflux period, remove the heating mantle and cool the flask to touch. Ammonium Hydroxide
is then added with stirring, at a rate of 5 ml/min. Care must be taken to assure ammonium
hydroxide vapors do not traverse the reflux condenser. The cooling water used in the reflux
condenser should be below 75°F to preclude the loss of Tetrahydrofuran and Ammonium
Hydroxide vapors. Comparison formula that is over 7 days old shall not be used.
4.6 Preparation of coated test panels. Test panels shall be made from aluminum alloy sheet
conforming to
ASTM B209. The panels shall measure 5 inches by 24 inches. The edges shall be broken and
smoothed. Panels shall be cleaned with a suitable solvent to remove any grease that is present.
Panels shall be prepared as specified in Table 1 and cured at 75° ± 2°F and a relative humidity of
50% ± 5%, for a period of 90 days prior to testing. After curing, apply several strips of 0.5 to 1.0
inch wide masking tape parallel to the 5 inch edge of the panel and spaced so that six 2.5 by 5
inch areas of coated surface are exposed between the strips of tape.
TABLE 1. TEST PANEL FINISHES
LACQUER PANELS "A"
Processing
Material
No. of Coats Drying Time
Drying Time
Baking
Step
and Coat
Between
Before
Conditions
Thickness
Coats
Baking
1
Coating,
Pretreatment,
MIL-C-5541, Class
1A
2
Coating,
One
30 min at
Pretreatment
0.2 to 0.3
Room Temp
Smooth Finish,
Mils
Spray Type
MIL-C-8514
3
Zinc Chromate
One
1 Hour at
Primer
0.3 to 0.4
Room Temp
TT-P-1757
Mils
150°F for 96
4
Lacquer, MIL-L-
Two
45 min at
24 Hours
81352,
0.5 to 0.6
Room Temp
Hours
Insignia White,
Mils
Color No. 17875
7
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