Spraying the surface several times seems to take more time. In fact, when spraying the second coat, use a hair dryer while spraying to speed up the volatilization of the solvent , which is faster than one thick spraying and the drying speed is also higher. The reason is that if the coating film is thick, the solvent will stay in the coating film and be difficult to volatilize. As mentioned above, the volatilization speed of the solvent is inversely proportional to the square of the film thickness. For example, if the film thickness of three coatings is sprayed once, then 3²=9, the volatilization speed will be greatly slowed down, and grinding and repairing will not be possible, and the final result will be a decrease in operating speed.
If the spraying is too thick at one time, the solvent residue will remain in the coating film and it is difficult to volatilize. As shown in the figure, the old coating film on the edge of the putty will be soaked and swelled, and it will wrinkle after spraying the topcoat, so the surfacer coating should not be done once. Spraying too thick is the so-called thick coating type surfacer, which does not mean that one spraying is very thick, but spraying several times, and the resulting secondary paste coating is thicker. (Recommended instrument: coating Thickness Gauge)
