Paint defect are common while spray painting and can be due to various factors in paint shop. Humidity & oil contamination is worst enemy in any paint jobs.
It is very important to understand in what environment you are doing the painting and the size of the equipment to be painted. People are least bothered about compressors, spray guns, dry sanding techniques, paint shop dust control, mixing ratio, paint filtration, clean air as all these would be required to have smooth flawless finish.
While painting selection of right primer & paint is required so that has excellent adhesion with substrate. Normally people tend to avoid these areas & expect a flawless finish.
Please understand 99% of paint problems arises cause of poor application techniques. We at Automotive Solutions not only supply & apply but also support our customers with right applications.