The humidity of   construction environment is too high or the solvent volatilizes too fast,   causing the moisture to condense.

Control the   temperature and humidity of the painting environment.

The paint film is not cured 

completely.

Strengthen   curing such as increasing the baking temperature, extending the baking time   and increasing the UV curing energy.

The coating   layer is too thin, showing the base color of the substrate.

Extend the   coating time to ensure the thickness of the coating layer.