The phenomenon that the coated surface is not painted due to missing coating is called exposed bottom, and the phenomenon that the bottom surface is not covered due to thin coating or poor covering power of the coating is called poor bottom cover.

Reason:

(1) The covering power of the paint used is poor or the paint is not evenly stirred before use.

(2) The construction viscosity (or construction solids) of the coating is low and the coating is too thin.

(3) The spraying is not careful or the shape of the coated object is complex, and the phenomenon of missing coating occurs.

(4) The color difference between the base and top paint is too large, such as applying light-colored paint with high brightness on the dark paint surface.

Prevention:

(1) Choose a coating with strong hiding power, increase the thickness of the coating or increase the number of spraying passes, and the coating should be fully stirred before use and during the coating process.

(2) Appropriately increase the construction viscosity of the paint or choose a paint with a high construction solid content, and each paint should reach the specified spray thickness.

(3) Improve the proficiency of spraying operation and operate with caution.

(4) The color of the base coat should be as close as possible to the color of the top coat.