Phenomenon：The surface of the paint film has small holes similar to those pierced by a needle, like leather pores, with a diameter of about 0.1mm. The number of pinholes is variable, mainly caused by the volatilization of solvents or small molecular substances or the internal stress difference between the substrate and the coating.

Phenomenon：The paint film appears like a crater with a raised depression on the edge, which is also called a fisheye or cave. Large shrinkage holes appear alone, while small shrinkage holes appear in pieces.

Phenomenon：The paint film presents more or less regular wave-like wrinkles with small amplitudes, which can be as deep as part or all of the film thickness.

Phenomenon：The "orange peel" phenomenon is that the paint film does not flow sufficiently and appears uneven, which looks like an orange peel.

Phenomenon：An opaque white film that occurs during the rapid evaporation of the solvent after the paint is applied. This is because the solvent quickly volatilizes and absorbs a lot of heat, causing the moisture adjacent to the drying paint film to condense on the paint film. Sometimes water in the solvent can also cause whitening. Generally speaking, the higher the volatility of the solvent, the greater the tendency of the paint film to turn white.

Phenomenon：The paint is applied to the surface of a vertical object. During the film formation process, the wet film flows downward under the influence of gravity, forming a film with uneven thickness, which is called sagging.

Phenomenon：The surface of the paint film is uneven and wavy.