1. Causes:
（1）The main reason is the substrate is polluted, and thorough cleaning and preparation are not carried out before painting.
（2）Spraying tools such as the spray gun are polluted.
2. Precaution and Correction Method:
(1) Need to clean the sprayed surface, remove wax, grease, polishing agent and other substances thoroughly.
(2) Make sure that tools such as compressed air, air supply pipes and spray guns are clean.
(3) If the blistering has occurred, polish the surface lightly, be careful not to polish through the paint film, and re-spray auto refinish paint products. If the situation is very serious, it should be polished to bare metal and then sprayed again.
