They are scratches or grooves produced in the sanding process that have not been covered or filled by the paint in subsequent layers.
The reasons why it happens are the following:
- Lack of drying or hardening of the sanded surface.
- Improper choice of the orbit of the sander.
- Improper choice of abrasive grain, between coats of varnish always use P800 as the last step.
- Insufficient amount of product to cover and fill the sanding grooves.
- Poor preparation of base coats.
Solutions to avoid it:
- Respect the drying time indicated in the technical data sheet before sanding.
- Depending on the layer of paint to be sanded, select the orbit of the sander (small orbits for topcoats).
- Select the appropriate abrasive grain based on the paint layer to sand, with funds at least finish with P400 and with colors and finishes P800
- Fine-tune sanded surfaces in order to apply the proper amount of product to cover or fill in marks
Repair
- Sand the surfaces until reaching the layer that has the defect.
- Do a sanding process of P400-P800 or even P1200
- Reapply product