Vehicle Body Restoration: Corrosion, Preparation and Refinishing
Core concepts
Restoration rewards understanding of corrosion mechanisms and surface preparation. A candidate must know how rust forms in seams, cavities and double panels, why media blasting, chemical stripping and mechanical abrasion suit different substrates, and how surface profile affects coating adhesion. Learn the coating system: pretreatment, primer, sealer, basecoat and clearcoat, and why each layer has a specified film thickness and flash-off time. Understand mixing ratios, pot life, spray environment, contamination control and the causes of defects such as solvent pop, orange peel, sinkage and blistering.
Traps to watch
Questions frequently test whether you know that painting over rust or silicone contamination causes failure, and that filler must not be applied over bare steel without the specified primer. Another trap is confusing primer types, or assuming more coats equal better protection when exceeding film thickness causes cracking. Watch for answers that ignore flash-off times, booth temperature or the need to strip back to sound substrate rather than feathering over corrosion.
Rule of thumb
Prepare until the substrate is sound and correctly profiled, then build the coating system exactly to the product data sheet. If in doubt, remove material rather than coat over a doubtful surface.
Worked example
A restored guard shows rust staining along a folded seam. The seam is opened, cleaned to bare metal, treated with a converter, primed, sealed and cavity-waxed before refinishing, and the repair is documented so the finish and protection can be verified later.