Sanding marks in the substrate show as lines in the surface of the refinish paint.
- The substrate was sanded with an abrasive that was too coarse. The paint shrinks more strongly in the sanding marks because of the higher film thickness
- The drying times for the undercoat materials were not observed correctly: The sanding marks are clearly visible due to the swelling of the undercoat materials at the time of painting and the sinkage after drying
- Filler and topcoat layers were applied too thin to cover the sanding marks in lower layers
- Wrong sanding technique and/or sanding machines used
HOW TO AVOID
- Use specified grade of sanding paper (P80/P150 for body filler, P240 for primer filler/filler – see relevant technical data sheets). Use guide coat for sanding.
- Keep to recommended drying times.
- Keep to recommended film builds.
- Place sanding machine on surface of paintwork before starting the machine. When dry sanding filler coats, the eccentric stroke should not be greater than 5 mm.
Denib and refinish using the recommended undercoats and/or topcoats.