The surface particles of the coating film seriously affect the appearance. For a small number of fine particles, use 15oo # water sandpaper to polish and modify. If there are many or large particles, use 8oo # water sandpaper to polish and then spray again. Particles on the surface of the coating film are the main reason for the high repair rate of advanced coatings (such as car coatings). Therefore, the key to coating particles is to take preventive measures. Factors causing coating particles are as follows.
(1) The working environment is dusty. In the layout of the workshop, it is necessary to carry out partition management, and the grinding section should be far above the spraying operation area. The floor of the workshop should be painted with floor paint to prevent dusting, and should be cleaned frequently to keep it clean. Humidification treatment should be carried out in the workshop to reduce dust flying.
(2) The paint is not filtered. After the paint is diluted, it should be filtered. The primer is filtered with a 120-mesh screen, and the topcoat is filtered with a 180-mesh screen.
(3) The paint that is easy to precipitate is not sufficiently stirred before thinning; or it is not gradually diluted as required during thinning, causing the pigment to flocculate and return to coarse (for example, carbon black in black paint is particularly easy to flocculate and return to coarse).
(4) There are poorly soluble resins, and when the poorly soluble thinners are diluted, they are insoluble and precipitated, resulting in resin particles; or broken paint remains in the paint.
(5) During the production of flash paint, the aluminum powder slurry is poorly dispersed, and many particles are produced during spraying.
(6) Since dust is easily absorbed by the electrostatic charge on the surface of the coating, it is better to use high-energy compression blowing and wiping with a sticky rag before spraying the topcoat. Many particles are caused by the fibers of work uniforms, spray booth filter materials or dry wipes, and measures should be taken to reduce fibrous particles.