The following procedures should be followed when repairing
all types of thermoset plastic:
- Use the supplies and the repair materials from the same manufacturer.
Do not intermix systems. Mixing materials from different manufacturers can
produce unsatisfactory results.
- Clean the inner and outer surfaces of the repair area with a soap
impregnated scouring pad in order to remove any dirt or mold release agent.
A mold release agent is used during manufacturing in order to prevent the
part from sticking to the mold. This release agent may be present in large
enough concentrations to affect adhesion.
- After washing, clean the area a second time with a wax and grease
remover. Use only enough of the remover to dampen a cloth. Too much of the
solvent will saturate the panel and may migrate out later, affecting the
finish. Use a tack rag and air for finish cleanup. Allow the panel to dry
thoroughly.
- Apply force around the damaged area in order to look for hidden
damage such as hairline cracks. Small cracks and faults in the bonds and the
panels will eventually grow larger if left unattended. Drill a 3 mm
(1/8 in) hole at each end of a crack in order to prevent any further
cracking.
- Remove the surface finish from the area to be repaired. Adhesives
are designed to adhere to the plastic substrate, not the finish.
- Prime a metal surface before applying the repair material.
- Repair the inner surface of the panel first.
- When using a mat reinforcement to repair the inner or outer surface
of a panel, inspect that there are no strands of the mat left uncovered or
unsaturated with the repair material. If exposed, the mat may act as a wick
and draw moisture into the repair area, affecting the integrity and the finish.
- Inspect the rear of the damaged panel for tool clearance. If accessing
the repair with a saturation roller, a grinder, or a sander is impossible,
do the repairs by hand.
- Align the damaged or spliced area with a brace and clamps if the
damage is severe. For a smaller repair, use a heavy tape on the outer surface
in order to maintain the alignment until the inner repair material has cured.
- If welding is necessary, do not allow the flame or the welding
heat to come into direct contact with the plastic body panels. Protect the
surrounding area with a fire retardant fabric. Several layers of aluminum
foil make an excellent heat shield if not in direct contact with the flame.
- Inspect the rear side of the work area before making repairs in
order to avoid possible damage to wires, motors, etc.
- Fiberglass parts will not yield or take a set as with steel parts,
thus they cannot be straightened. If poor alignments are suspected, due to
a collision or other damage inspect the steel reinforcements for damage and
replace or repair them before repairing the plastic parts.
- Save any useful size pieces of repair material when cleaning up
the work area. These pieces can be used for reinforcing smaller repair areas.
- Force dry structural bonding epoxy with heat. Heat speeds the
cure time and increases the bond strength. Follow the manufacturer's curing
recommendations.