The essence of the Bernard vortex is the change in surface tension caused by the viscosity change during the melt-solidification of the powder coating, which causes the fluid with high viscosity and low surface tension to sink to the middle (recess) of the vortex, and the low viscosity is high. The surface tension fluid rises to the periphery (convex) of the vortex until the curing is completed. In this process, the gas (air) in the original loosely stacked voids after the coating will collect and form bubbles when the powder melts and collapses, and small molecular gases from the inside of the coating or the substrate will also gather to form bubbles. And was drained. As the viscosity of the system continues to increase as the curing progresses, the air bubbles trapped in the Bernard vortex eventually form pinholes during the discharge process. Therefore, to prevent and eliminate pinholes in powder coatings, it is necessary to analyze the root cause of small molecules (bubbles) in the coating, and then take appropriate measures to prevent and resolve pinhole defects in the coating film.