The whitening of the paint film means that after the paint is painted, the paint film becomes white and loses luster during the drying process, showing turbidity or white spots, uneven luster, and fragile texture. The reason is:
(1) When spraying or brushing nitro paint and foreign dry paint, it is very easy to appear whitening. If the construction environment is relatively humid, or during the drying process, the solvent evaporates too quickly, the surface temperature of the paint film drops sharply, and the water condenses on the paint film, a layer of white milky body formed by water and paint will appear, that is, "whitening". Phenomenon.
(2) There is a lot of water in the tools for spraying or brushing paint. When the water is mixed into the paint during construction, the paint film will be partially whitish.
(3) If the moisture content of the wood is too high or the wall is not dry, after the paint is painted, the water will be mixed into the paint film, which will also turn white.
(4) The dried foreign paint film will also turn white when it comes into contact with hot teacups, hot pots, etc.
In order to prevent the whitening of the paint film, it is necessary to pay attention to:
(1) Nitro paint and foreign dry paint are not recommended to be applied in rainy or cold weather. If construction is required, the temperature should be raised to 15~2o℃, and the relative humidity should not exceed 7o%. Choose an organic solvent that evaporates slowly, or add 1o%~2o% nitro paint moisture-proof agent to the spray paint. In order to prevent the whitening of the foreign dry paint, 10% rosin can be added to the solution to reduce the whitening.
(2) The nitro paint is whitish, you can heat it up with an infrared heater, and then spray a layer of nitro paint with a moisture-proof agent on the paint film; Or burn with fire.
(3) The thinner in the paint should not be added too much, and the tools for spraying or brushing and the compressed air should not contain moisture.
(4) Newly built houses should be repainted after a period of time, and doors and windows should be opened as much as possible to make the walls dry faster. There is enough carbon dioxide in the room, which can accelerate the carbonization of calcium hydroxide and reduce the alkalinity of the wall.
