in sheet metal processing, why are there pinholes in sheet metal processing and painting, and how to solve them? The following is a detailed introduction:

condition: needle-punched holes, deep and intermediate paint. Reason: glass fiber substrate; Insufficient mixing of polyester filler (putty); Solvent bubbles still remain on the polished surface; Insufficient priming of polyester filler (putty).

Prevention method: thoroughly mix polyester filler (putty); do not polish solvent bubbles or completely remove the problematic paint film; fill sufficient polyester filler (putty).

Condition: Paint with blisters and blisters. Reason: The solvent air is hidden in the paint film and escapes afterwards, leaving bubble marks. Common causes are as follows: the paint film is sprayed too thick and dried too quickly on hardener or thinner; The spray gun nozzle (caliber) or spraying viscosity or spraying air pressure is incorrect; Insufficient standing time before heating and drying or insufficient air flow in the paint booth.