Paint film loss of gloss means that the glossy paint does not emit light after the film is formed. Paint film backlight refers to the phenomenon that the paint film is shiny at the time, and the gloss gradually decreases in a short period of time (hours or even weeks).
The causes and prevention methods of paint film loss and reflection are roughly the same:
(1) The surface to be coated is porous or quite rough, and cannot be shiny after being coated with glossy paint. It can be prevented with proper surface preparation.
(2) Shellac paint and lacquer paint need to be painted many times on a flat and smooth bottom layer before they can be bright. If it is only removed for 1 or 2 times, it will not show light; if the amount of cooked tung oil in the lacquer is too small, the paint film will also be semi-glossy or dull.
(3) Kerosene or diesel oil is mixed into the paint. Because kerosene and diesel oil have poor solubility to paint, it is easy to make the paint thicker, so that the paint film is semi-glossy or dull.
(4) The amount of thinner is too much, which reduces the solid content, and the number of times of painting is small, and the proper thickness cannot be achieved, resulting in a dull paint film. For this reason, the amount of diluent should be limited to 8%~10%.
(5) Use paint with too much pigment to paint. If it is not stirred evenly, the upper half of the bucket will have less pigment and more paint, and it will be shiny after l removal; .
(6) Several kinds of paints with different properties are mixed and painted with topcoat, or too much moisture-proof agent is added to nitro varnish, which will cause loss of gloss.
(7) The construction environment is not good, the surface to be coated has oil stains, moisture or the climate is humid, the construction environment temperature is too low; the construction site is not clean, there is too much dust, or wind, rain, soot, etc. are encountered during the drying process , The paint film is also prone to semi-gloss or dullness. Especially the tung oil coating, in case of wind, rain and soot, is easy to lose its gloss, just like brushing the primer once, without a little gloss.
(8) Paint the topcoat before the primer and putty are completely dry, which will also cause loss of gloss.
(9) Use paint with poor light fastness, and the paint film will lose light selection soon after being exposed to sunlight. If the paint film loses its gloss, it should be repainted after drying. Treat the cause of the loss of light to prevent loss of light and back light.
