Prepping a car for a paint job is a meticulous, multi-step process that is arguably more critical than the painting itself. Proper preparation, or "prep," ensures the new paint adheres correctly and lasts for years. The core steps involve a complete cleaning, stripping the old paint to a stable base, repairing any dents or rust, meticulously sanding the entire surface to create a "tooth" for the primer to grip, applying primer, and finally performing a thorough decontamination before moving to the paint booth. Skipping or rushing any of these steps will compromise the final result.
The first and most crucial phase is disassembly and cleaning. Remove all trim, lights, door handles, and badges if possible. This prevents overspray and allows you to paint edges properly. Then, give the car a deep wash with automotive soap and degreaser, paying special attention to areas like the wheel wells and lower panels where grime builds up. Any contamination left on the surface will be trapped under the new paint.
Next, you must address the bodywork. This means repairing dents with body filler and grinding out all rust completely. It's vital to remove every speck of rust and treat the bare metal with a rust inhibitor; otherwise, the corrosion will bubble through your new paint. Once the body is straight, the entire surface must be sanded. You'll typically start with a coarse grit (like 180 or 320) to remove the clear coat and most of the color coat, then progressively move to finer grits (400, 600) to create a smooth, uniform surface. The goal is to "feather" the edges of any remaining old paint so there are no hard lines.
After sanding, the car must be blown down with compressed air and tacked with a tack cloth to remove every particle of dust. Then, you apply a high-build primer. This primer serves two purposes: it seals the surface and can be block-sanded to reveal any remaining minor imperfections in the bodywork. Once the primer is sanded smooth, you perform a final cleaning and move the car into a dedicated, dust-free painting environment. The final prep step is a wax and grease remover wipe-down immediately before painting to eliminate any oils from your hands.
| Prep Step | Key Action | Recommended Materials/Tools | Common Mistake to Avoid |
|---|
| Disassembly | Remove trim, lights, emblems | Trim removal tools, labeled bags | Painting over trim, creating ugly overspray lines |
| Cleaning | Deep wash and degrease | Automotive soap, degreaser spray | Not cleaning wheel wells; wax residue causing fisheyes |
| Rust/Dent Repair | Grind out rust, apply body filler | Angle grinder, rust converter, body filler | Not fully removing rust, leading to future bubbles |
| Sanding | Feather edges, create uniform surface | Dual-action sander, 180-600 grit sandpaper | Sanding through the primer surfacer into bare metal |
| Priming | Apply high-build primer, block sand | Spray gun, primer surfacer, sanding block | Not sanding primer smooth, leaving sanding scratches |
| Final Decontamination | Blow down, tack cloth, wax/grease remover | Compressed air, tack cloth, lint-free wipes | Skipping the tack cloth, leaving dust under the paint |
