Why do particles and dust appear on the surface of the film?

(1) phenomenon

The phenomenon that the protrusions in the coating film are distributed in the form of particles on the entire or partial surface is called particles; the bumps caused by foreign matter mixed into the paint or the deterioration of the paint are called paint particles; The raised foreign matter caused by it is called metal particles; the dust or foreign matter attached to the wet coating film during painting or just after painting is called dust. The surface of the coating film is rough and uneven by hand, as if many impurity particles are trapped on the surface of the coating film or covered by the coating film. As shown in Figure 9-7.

(2) Reason analysis

The main reason is that impurity particles are mixed or stained in the coating film.

① The air cleanliness of the coating environment is poor. Unfiltered or improperly filtered air in spray booths, drying booths, or ovens.

② The surface treatment of the base material is not clean, and it has not been wiped clean with viscous gauze before spraying.

③Paint mist particles and dust are accumulated in the spray booth.

④ The dust in the gaps and grooves of the vehicle has not been blown clean.

⑤ The compressed air is not filtered or improperly filtered. (Related instruments: Air Compressor)

⑥ The lid of the tank containing the paint is not tightly closed, allowing dust to enter; using rusted or dirty containers and stirring rods; and not filtering the paint before use. (Related instrument: Stirrer)

⑦ The cement or other dust-generating floors in the painting workshop have not been sealed or wetted; dry sanding, grinding, polishing, etc. in the spraying area; use poor quality masking paper. (Related instrument: grinding machine)

⑧Paint deterioration, such as paint base precipitation or anti-coarseness, poor dispersion or agglomeration of pigments, precipitation of organic pigments, poor dispersion of aluminum powder in flash paint, etc. (Related instrument: dispersing machine)

⑨ Dust brought by the operator. Dust, dirt and fibers on work clothes.

(3) Preventive measures

①Establish a good dust prevention and cleaning management system. Regularly and effectively clean the painting workshop, painting equipment and air supply system to ensure a clean painting environment.

②Seal the surface that will generate dust.

③ Before the vehicle is sprayed, or before entering the spray booth, it needs to be cleaned effectively, especially the grooves and crevices. Vehicles need to be kept effectively clean at every stage of painting.

④Strictly control the quality of paint, and transition is required before use.

(4) Remedy

①When the defect is light, after the paint film is completely dry, then wet sand it with very fine sandpaper, and then polish it to reproduce the luster.

② When the particles are deeply sunken, level them and spray again.