The appearance of orange peel and pinholes in the spray plastic can not be judged as a spray gun problem, nor can it be directly identified as a plastic powder quality problem. Orange peel is more commonly found in film thickness, powder leveling, spray gun powder/airflow/electrostatic parameters, gun spacing, curing, and pretreatment; pinholes are more common in substrate or pretreatment residues, moisture and oil stains, powder moisture, gas release, film thickness does not match curing, compressed air pollution, and other factors. The correct approach is to distinguish the defect form first, and then gradually lock the root cause by "different guns with the same powder, different guns with the same powder, different workpieces with the same gun with the same powder, standard test plate control, single variable test spray".
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