What problems should be paid attention to in paint construction in high temperature weather?

First of all, there is relatively more rain in summer, especially in rainy season. After every rain, because of the evaporation of water, the air humidity is particularly high, and painting is very easy to turn white, especially nitrocellulose paint. At this time, we should pay attention to the construction, and there are two preventive methods:

1. Add an appropriate amount of waterproof white water (no more than 8% of the total thinner) when preparing paint; 2. Wet the site before painting.

Second, paint bubbles easily in hot weather. Painters generally use less curing agent to avoid foaming, and some people even add only 50% of the standard amount! Actually, this is a misunderstanding. Reducing curing agent can't substantially avoid coating foaming, but it will lead to incomplete coating reaction, resulting in soft paint film and poor adhesion. If it is a primer, it is easy to cause undercut, and if it is a high-grade topcoat, it will also cause unstable luster.

The main reason why paint bubbles easily in summer is that the surface of paint film dries too fast. Generally, a proper amount of slow-drying water is added to the diluent (generally not more than 10% of the diluent). Even if less curing agent is added, it is recommended that the primer and semi-dull topcoat be no less than 1:0.45, and the glossy topcoat be no less than 1:0.8.

Bright topcoat is particularly prone to prickly heat and pinholes in summer. The reason is: after the paint is sprayed, due to the high temperature and rapid evaporation, the paint surface layer quickly forms a film, which prevents the nonvolatile diluent below the surface layer from penetrating to the surface layer and forming needle-like pores. The only way to solve this problem is to reduce the surface drying speed of paint. For example, lowering the ambient temperature, using slow-drying thinner and reducing curing agent can only prolong the rising time of paint hardness, but can not prolong its surface drying time, so it can not effectively remove prickly heat.

Third, there are many mosquitoes in summer, and the paint is easy to fall on the surface of the paint film during the drying process, resulting in paint rework. It is suggested to do the following in the rework process:

1, polished thoroughly. Wax slurry is generally added to the top coat to increase the smoothness of hand feel. If it is not fully polished before repainting, delamination will occur.

2. When polishing, the sandpaper should not be too thick. During the service, we found that many masters used 240 or 320 sandpaper, or even thicker. Too thick sand marks need thicker paint film, which leads to poor transparency, and finally they are spliced into panels of different colors. In contrast, more than 320 imported sandpaper is used for grinding. Although the sandpaper on the surface is expensive, only a thin layer is needed when the topcoat is actually repainted, which not only saves the paint, but also makes the surface repainting not obvious. Four, the general factory has thinner in winter and summer, and it is best to use the corresponding thinner in high temperature weather, which is easier to construct.