What Causes Bubbles in Paint?
1 Answers
Bubbles in automotive paint can be caused by improper construction conditions and processes, such as oil stains, dust, sweat, or other contaminants on the surface being painted. These impurities can trap moisture, excessive temperature differences between the paint and the surface, improper use of thinner, or excessive addition of hardener. Causes of the phenomenon: Gas trapped within the coating breaks through the surface, forming bubbles that may burst or wear away, creating pinholes. When the surface of the coating dries slightly faster than the interior, and the internal solvent or air continues to evaporate after the surface has begun to set, bubbles may form as the gas breaks through the surface. Solutions: Use the appropriate amount of thinner and hardener, adjust the paint viscosity to the correct level, and control the spray thickness. Properly fill and sand the substrate to eliminate contamination. Adjust the air pressure appropriately to minimize air entrapment—typically, the pre-gun pressure gauge should be set at 0.2MPa. Improve the working environment by controlling temperature and humidity. Extend the recoating time to allow the lower layers to dry thoroughly. Let the mixed paint sit for 10 minutes before spraying. When using heat drying for the coating, control the standing time to allow solvents to fully evaporate before preheating the coating.