Why control the thickness of the coating?
A coating with a certain thickness can be formed once or multiple times. Practical experience shows that for most paints, it is advisable to apply multiple coats each time. The performance of the paint film formed by multiple coatings is better than that of the same thickness of the paint film formed by coating once. This is because the thin coating has good drying conditions, small internal stress during drying, and good adhesion. The coating is too thick . When drying, not only the internal stress of drying is large, but also prone to wrinkling and other morbidity.
In fact, except for poly-Han paint, it is impossible to apply a very thick coating for other coatings. If the brush is too thick, it is easy to wrinkle and the vertical surface is easy to hang; when spraying, due to the fine atomization , it is impossible to spray thickly at one time; when rolling coating, if the coating is too thick, the paint is easily pressed out of the edge of the board by the paint stick; and so on.
Paint coating thickness is divided into the following reference thickness:
(1) The general coating is 30-40 microns.
(2) The decorative coating is 35~45 microns.
(3) The protective coating is 125~130 microns.
(4) The wear-resistant coating is 130~150 microns.
(5) Thick coating with high solid content is 700~1000 microns.
How to measure coating thickness?
(1) Determination of wet film thickness. The simpler method is to use a metal plate that can be carried in a pocket, with rectangular teeth on both sides, the two planes at the two ends are on the same level, and the middle teeth There are different heights ascending successively from the horizontal plane. When in use, touch it vertically to the test surface, and the maximum reading of the tooth-shaped adhesion wet film is the thickness of the wet film.
(2) Measure the dry film thickness. Dry Film Thickness Gauges are commonly used today. It is also possible to use mechanical methods, such as a lever dry ruler, etc. to measure the thickness of the coating on the metal base plate. Due to limitation of the structure of the lever and the ruler itself, it can only be used to measure the test plate with a small area.
For other substrate materials used for coating, such as glass, wood, paper, etc., to measure the thickness of the paint film, a lever is generally used on a ruler. Measure the thickness of the glass bottom plate first, then measure the total thickness of the glass plate and the paint film after the paint is applied, and subtract the thickness of the glass bottom plate from the total thickness to obtain the thickness of the paint film.
(3) With the development of science and technology, more and more electronic Thickness Gauges are used at present, which are measured by magnetoresistance method, eddy current method or ultrasonic coating Thickness Gauge, with high precision, fast and effective.
