Sagging refers to the phenomenon that there are traces of auto paint liquid flowing downward on the coating film. Mostly appear on vertical surfaces or corners. Generally, those that appear on the vertical surface are curtain-like sags, and those that appear on the corners are tear-stain-like sags. The reasons are:
(1) Excessive thinner or incorrect thinner is used, so that the viscosity is lower than the normal construction requirements, and the automotive paint cannot be attached to the surface of the object, causing it to fall and flow.
(2) The temperature of the construction environment is too low, the drying speed of the sprayed car paint is too slow, and the solvent is not easy to volatilize, resulting in the accumulation of too much thinner in the paint film, and the paint film will sag. Winter is a period of high incidence of sagging, which requires special attention.
(3) Improper use of the spray gun. The distance between the spray gun and the object to be coated is too close, the speed of the gun is too slow, and the spraying is too thick at one time, etc. will increase the possibility of sagging.
(4) After painting, there is not enough drying time between the paint layers.
According to the above reasons, the methods of preventing car paint sagging include:
1. Use the recommended type of thinner, and dilute the paint according to the correct mixing ratio, so that the construction viscosity is within the process range.
2. Use the correct spraying method and adjust the spray gun properly.
3. Ensure the temperature of the construction environment and allow enough drying time.
4. When the sagging phenomenon of the car paint is slight, after the paint surface is dry, wet sand the defective area with fine sandpaper, and then wax and polish it. If the sag is severe, the defective area will need to be sanded and repainted.
