Paint preparation — the foundation for a durable result
Why the vast majority of paint work happens before the paint goes on
A nice lacquer finish rarely comes from the spray itself. It comes from the preparatory work. Lacquer highlights every unevenness beneath it, so if the surface is not clean, level and correctly primed, the faults will appear clearly as soon as the lacquer dries. Lacquer preparation is therefore the car body technician's patience work.
§Cleaning and degreasing
All work begins with a clean surface. Grease, wax, silicone and dirt must be removed before sanding, otherwise the contaminants are pressed down into the surface. Degreasing is repeated between several steps, because even fingerprints can cause defects in the finished paintwork.
§Grinding and puttying
Grinding creates adhesion and removes old, loose varnish and rust. Minor irregularities are smoothed out with putty, which is sanded flush when cured. Work through increasingly finer sanding grit so scratches from one step are sanded away in the next. A surface that feels smooth to the hand but not to the eye is not yet finished.
Typical step sequence
- 01Clean and degrease the entire area.
- 02Sand old varnish, rust and edges down to solid substrate.
- 03Spackle unevenness and let the spackle cure completely.
- 04Sand the filler flush and check by hand along the surface.
- 05Degreased again and applied primer/filler primer.
- 06Sand the primer lightly and degrease once more before varnishing.
§Priming
The primer binds the substrate and paint together and provides a uniform, absorbent surface. Filler primer can smooth fine scratches, while a separate primer provides adhesion and rust protection. Choose primer according to the substrate — bare metal, filler or old paint have different requirements.
§Work environment and health
Paint products and sanding dust can be harmful to health. Use proper respiratory protection, gloves and eye protection, ensure extraction, and follow the safety data sheets for the products you work with. A good paint result is never an excuse to compromise your own safety.