Century Estate Wagon L4-151 2.5L (1985)
The immediate problem involved with breaking through the surface is that when the surface is broken (by sanding or by some other means) the bare
metal is exposed to air and moisture - and the possibility of future corrosion.
A second reason to avoid breaking through the surface is that there is always the possibility of a color mismatch in areas that are repainted.
Factory Painting Materials and Methods
There are two assembly line painting methods used, each with its own set of properties. One method uses thermo-flow acrylic lacquer finishes, while the
other uses thermo-set enamel finishes.
Figure 2 - Acrylic Lacquer Curing Process
Acrylic Lacquer
A thermo-flow acrylic lacquer finish is applied and reflowed in ovens at temperatures of approximately 325~ Fahrenheit, so the paint surface flow
together. The paint cures by solvent evaporation and the result is a level, glossy coat that requires little or no compounding (Figure 2). Because of the
heat involved, the acrylic lacquer cannot be reflowed after any plastic, rubber or glass is mounted on the car.
Figure 3 - Acrylic Enamel Curing Process
Acrylic Enamel
Heat is also used to cure thermo-set acrylic enamel finishes. However, unlike acrylic lacquers which only undergo a process of solvent evaporation when
curing, enamels undergo an additional process of absorption of oxygen from the air (Figure 3). Enamel provides a durable, lustrous finish that cannot be
reflowed once it is cured.
When you're called upon to correct a paint imperfection, don't break the surface unless it's absolutely necessary!
Simple Finish Repairs
Depending on the nature of the imperfection, you may be able to correct it using measures that won't disturb the color coat or undercoat. When possible,
attempt to rub out and polish the imperfection. If necessary, wet sand the imperfection with ultra-fine or equivalent sandpaper, then rub out and polish
the area. To correct dirt in paint conditions use a dirt-nib file
to remove dirt speck (nibs) without disturbing surrounding surface. But whatever the case, always use the simplest possible method to repair an
imperfection.
