General Plastic Repair Instructions
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 naptha solvent. 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.
Some adhesives require the use of a primer when bonding to metal. Use only the primers that are approved by the manufacturer'*. If you are bonding a composite panel to a metal surface, follow the adhesive manufacturers recommendations on how the metal should be prepared.
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.
Composite 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 manufacturers curing recommendations.
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