Panel Preparation, Damage Assessment, and Metal Finishing
Damage assessment
Classify damage as direct (impact area) and indirect (transferred damage). Check for stretch, kinks, and misalignment. Use a damage report to record severity, and decide whether a panel can be repaired or must be replaced. Know the difference between plastic deformation (permanent) and elastic deformation (springs back).
Metal finishing
Repair sequence: rough out with a hammer and dolly, then refine with a pick and file, then fill. Use a body file to reveal high and low spots - it cuts high spots and skips low spots. Heat shrinking is used on stretched areas using a torch or shrinking hammer; apply localized heat then quench to shrink metal. Over-stretching from too much hammering is a common trap.
Traps
Questions often test that a low spot is not hammered out from the outside but pushed out from behind with a dolly. Another trap: applying body filler over rust or bare metal without proper prep - filler adheres poorly to rust. Also, filler should not be used to bridge a dent that should be metal-finished first. Sanding direction matters: cross-sanding reveals defects.
Rule of thumb
"High spots get hammered, low spots get dollied." Rough out first, finish last - never sand before the metal is shaped.