01 March 2005
15 July 2008
appropriate. Unless otherwise specified, equipment
shall be coated with Flat Medium Gray, Color Number
5-4.1. GENERAL. Encapsulants are materials used to
shall be replaced with Stencil Marking Set (Volume IV,
cover a component or assembly in continuous organic
resin. Encapsulants provide electrical insulation,
resistance to corrosion, moisture, and fungus, and
mechanically support the components. In military avionic
equipment, encapsulants are classified as follows:
b. For Army applications, the topcoat shall be
Coating, Aliphatic Polyurethane, Chemical Agent
a. Potting compounds used to seal electrical
c. Air Force personnel should refer to TO 1-1-8 for
b. Conformal coatings used to encapsulate PCBs
proper color and paint systems. MIL-PRF-85285 is the
and modules. Refer to NAVAIR 01-1A-23 (Navy) or TO
preferred topcoat for Air Force avionic equipment.
00-25-234 (Air Force).
5-3.2.3. Thinners. Thinners are volatile solutions used
c. Fungus proof coatings, usually varnish, used to
encapsulate certain avionic circuit components in a thin
to thin or reduce paint to the desired consistency. The
protective film that is impervious to fungus attack.
type of thinner that may be used and the recommended
Usually used in older macroelectronic and electrical
quantity are usually stated on the paint container.
Prolonged breathing of vapors from organic
Refer to NAVAIR 01-1A-505 (Navy), TO
solvents or materials containing organic solvents
00-25-234 (Air Force), or TM 55-1500-323-24
is dangerous. Refer to DOD Instruction
(Army) for additional information and application
6050.5-LR, OPNAVINST 5100.23, TB MED
procedures on potting compounds.
502/DLAM 1000.2, or AFOSH STD 48. When
in doubt, contact the local Safety Officer.
5-4.2. POTTING COMPOUNDS. Potting compounds
are used for their moisture-proof and reinforcement
5-3.2.4. Local air pollution regulations may restrict the
properties. They are used on electrical connectors to
use of many coatings and thinners in some areas.
protect against fatigue failures caused by vibration and
T h i n n e r Aliphatic Polyurethane, MIL-T-81772
lateral pressure at the point of wire contact with the pin.
Potting compounds also protect electrical connectors
MIL-PRF-23377, MIL-PRF-22750, MIL-C-46168, and
MIL-PRF-81352 coatings. MIL-PRF-85582 shall be
exclusion of moisture, stray particles, and aircraft liquids
thinned as specified by the manufacturer.
(hydraulic fluid, fuel, and oil).
5-3.3. APPLICATION OF COATING. The method used
5-4.2.1. Materials. The following materials shall be
t o apply or touch-up paint systems or apply
used for "potting" electrical connectors.
materials, tools, facilities, and time available. Spraying
is faster than other methods and results in a smoother
surface finish. However, the time and labor required to
Potting compounds shall comply with the
set up spray equipment may not be justified by the
requirements of specifications MIL-PRF-8516
amount of work to be done or if extensive masking is
and MIL-A-46146, except where substitutes
required. Brushes or rollers are used where the use of
are specifically authorized by the cognizant
spray guns is Impractical or unsuitable. All painting
procedures and operations will be completed in
accordance with Volume II of this manual (Navy),
a. S e a l i n g Compound, Synthetic Rubber,
TO 1-1-8 (Air Force) or TM 55-1500-345-23 (Army).
A c c e l e r a t e d , MIL-PRF-8516 (Volume I V or V,