Why Does The Car Paint Appear Pinhole?

After the car paint spray, the surface of the car paint film appear needle-like holes, this phenomenon is called pinholes. In the paint drying process, what is the main reason for the emergence of pinholes?
1.when the paint is painted, the paint is too thick, the general situation is three times, but you spray four or five times, when the paint film is dry, car paint thinner and air contact time is too long, when they reach the surface of the film, so can only break out, this time there is no way to recover the pores, so left some pinholes.
2.if the solubility of the diluent is too strong, it is easy to break through the film to form small pinholes, according to the ambient temperature to use different types of thinner.
3.After spraying the film, the temperature can not rise too fast, because the film surface heating too fast, resulting in only dry appearance. The thinner and air break the paint surface to form pinholes.

If pinholes appear, need to be polished to the primer layer, fill the pinhole and then re-spray the primer, then re-spray.