Spray Painting, Refinishing and Colour Matching
Spray Painting, Refinishing and Colour Matching
The exam tests the paint system, gun setup, application technique and the practical steps for matching an existing finish.
Core rules
- A typical system is pretreatment, primer, basecoat and clearcoat; two-pack products need the correct hardener and induction time.
- Gun setup: HVLP gravity gun with a 1.3–1.4 mm nozzle for basecoat, about 2 bar at the cap, 15–20 cm spray distance, 50% overlap.
- Apply thin coats with flash-off between; heavy coats cause runs and solvent popping.
- Colour matching starts with the vehicle's paint code and variant; spray a test card, compare under daylight or a colour booth, then blend into adjacent panels.
- Metallic and pearl colours change with spray orientation and distance; keep the gun parallel and consistent.
- Booth cleanliness, tack rags and a filtered air supply prevent dirt.
Worked example
A silver metallic door is painted but looks darker than the wing. Reasoning: the basecoat may be too wet or the gun too close, which flips the metallic. Check the variant, spray a test card at the same distance, adjust technique, and blend into the wing rather than painting a hard edge at the door.
Traps
Matching colour under fluorescent light only, using the wrong primer shade under a metallic, and adding too much reducer. Also, failing to blend and leaving a visible panel edge.