2. Enamel System for Metal - On clean metal, spray one coat of RANDOLPH Wash Primer, Rand-O-
Plate or Epibond Primer. After it is dry, spray one very light mist coat of RANDOLPH Enamel over
primed surface. Follow in 15 to 20 minutes with one normal coat of enamel. Enamel should dry at
least 48 hours before masking for lettering.
TRIM AND REGISTRATION NUMBERS
When aircraft is being painted, apply predominant color first over entire surface. Apply trim colors over
base color after it dries. When top of fuselage is to be painted white with a dark color adjoining it, apply light
color and feather into area to be painted with dark color. When light color has dried, place masking tape and
paper along line of separation and spray dark color on.
Allow paint to dry for several hours before removing masking tape. Remove the tape by pulling slowly
parallel to surface. This will reduce the possibility of peeling off finish with tape.
Registration numbers may be applied by either painting or affixing self-adhering plastic figures. They must
be formed of solid lines using a color that contrasts with background. The location and size of identification
numbers vary, depending on size of aircraft. The location and size is found in Federal Aviation Regulations.
PAINT SYSTEM COMPATIBILITY
Before painting, determine what type of finish was used previously. Refer to Piper parts catalog for correct
paint number and color.
To identify paint finishes, first apply a coating of engine oil to a small area of surface to be checked. Old
nitrocellulose finishes will soften within a period of a few minutes. Acrylics, urethanes, and epoxy finishes
will show no effects.
If not identified, next wipe down a small area of the surface with rag wet with methy ethyl ketone. MEK
will pick up pigments from acrylic finishes, but not from epoxy or cured urethane coatings. Wipe surface,
don’t rub. Heavy rubbing will pick up even epoxy and urethane pigments from coatings that aren’t fully cured.
The use of several different types of paint, coupled with several proprietary coatings, make repair of
damaged and deteriorated areas particularly difficult. Paint finishes are not necessarily compatible with each
other. The following general rules for compatibility are included for information and are not necessarily listed
in order of importance.
1. Old type zinc chromate primer may be used directly for touchup of bare metal surfaces and on interior
finishes. It may be overcoated with wash primers if in good condition. Acrylic lacquer finishes will not
adhere to this material.
2. Modified zinc chromate primer will not adhere to bare metal. Never use it over a dried film of acrylic
nitrocellulose lacquer.
3. Nitrocellulose coatings will adhere to acrylic finishes, but reverse is not true. Do not use acrylic
nitrocellulose lacquers over old nitrocellulose finishes.
4. Acrylic nitrocellulose lacquers will not adhere to nitrocellulose and epoxy finishes and to bare metal.
For best results, lacquers must be applied over fresh, successive coatings of wash primer and modified
zinc chromate. They will also adhere to freshly applied epoxy coatings (dried less than 6 hours).
5. Epoxy topcoats will adhere to all paint systems that are in good condition. Epoxy may be used for
general touchup, including touchup of defects in baked enamel coatings.
6. Old wash primer coats may be overcoated directly with epoxy finishes. A new second coat of wash
primer must be applied if an acrylic finish is to be applied.
20 - 25 - 00
Page - 20 - 22
Reissued: August 1, 1986
1F1
PIPER AIRCRAFT
PA-28-236
MAINTENANCE MANUAL
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