1. Types of flowing and hanging
The flow mainly occurs on the façade of the large surface, and usually has two shapes, one is the flow like several tear marks, and the other is like the seawater falling in waves, with one or several falling marks. Sagging occurs mainly on edges or corners, like tear stains.
The influence of flow and sag on the coating quality is mainly different according to the layers of the coating, such as the flow and sag produced by the primer layer and the intermediate paint layer, as long as the paint film is dry (related instruments: flow If it occurs on the surface of the topcoat or the ribbon paint of a bus, it needs to be fully ground and then repaired.
Second, the cause of flow and sag
Spray air pressure is too high and gun is moving too slowly.
Too much thinner is added, and the paint quality is too thin. Spraying too close together. (Related instrument: viscometer)
Improper addition of thinner, such as thinner volatilization speed is too slow and paint film leveling time is long, resulting in flow and sagging.
Spray paint film too thick on the facade. Flowing and sagging are not only easy to appear in the refurbishment painting, but also easy to occur in the color changing painting without being noticed.
3. Preventive measures
Correct use of thinner and correct deployment of spray viscosity.
Control the spraying air pressure, master the spraying distance and the moving speed of the Spray Gun.
When spraying the facade, care should be taken that it should be thin but not thick. (Related instrument: Coating Thickness Gauge)
Pay attention to turn off the gun more and spray less when spraying the edges and seams.
When spraying good leveling properties such as alkyd paint and amino baking paint, it should be noted that the spraying distance should be moderate and not too close.
When spraying low-viscosity metal color paste and other paints, it should be noted that the spraying pressure should not be too high.
