The air in the coating environment 

is not clean, such as dust, paint 

mist, etc. Silicones or waxes are 

used around the coating 

environment.

Control the   cleanliness of the construction environment.

The coating   environment temperature is too low and the humidity is too high.

Control the   temperature and humidity of the painting environment.

Paint mixing tools as well as 

equipment，the painting tools, 

work clothes and gloves are not 

clean.

Ensure the   cleanliness of coating equipment and tools and the quality of compressed air.

The substrate is   poorly degreasing, and foreign matter such as water, oil, glue of the masking   tape, dust, soap, sanding dust, etc. adhere to it.

Strengthen the   surface treatment of the coated object to prevent the paint film from being   defective due to foreign objects.

The old coating film is not polished completely, and there are defects 

such as pinholes and depressions.

Carefully   polish, choose the appropriate sandpaper model and polishing method to   eliminate the influence of the old film.

The coating film is too thick.

Reduce the oil output of the 

spray gun to speed up the 

spraying speed and reduce 

the number of spraying.