Seven skills of spray painting and painting water-

2022-07-22
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Painting: painting machines are expensive, and generally painters are not equipped. The advantages of painting are: fast construction, good flatness, no poor texture. The disadvantages of painting are: large paint loss and troublesome post maintenance, because during post maintenance, workers can no longer pull the painting machine to repair, but can only use a brush. The texture of the brush is definitely different from that of the spray

painting: the construction is relatively slow. However, the paint surface has rolling texture and pattern, which is convenient for maintenance. The disadvantages of painting are: the effect of large surface rolling coating is different from the brush lines in the inner corners and lamp slots, and there are texture differences

at present, many paint companies promise to paint for the owners free of charge, but they are basically not responsible for the base treatment, and the base treatment of emulsion paint is the most important, because the base problem directly reduces the final decorative effect of emulsion paint. In addition, the loss of painting is relatively large, which is not particularly affordable

◆ seven skills in the construction of water-based coatings

spraying method is one of the most important methods in the construction of water-based coatings. Coating the surface of objects with spraying method can obtain a thin and uniform coating film. For different geometric shapes, small holes, gaps and uneven places, the coating can be evenly distributed; For spraying large surfaces, it is faster and more effective than painting. However, some operating skills must be mastered when using spraying method:

1. Adjust the coating to the appropriate viscosity of spraying with clean water, and measure it with tu-4 viscometer. The appropriate viscosity is generally 20~30 seconds. If there is no viscometer at the moment, visual inspection method can be used: stir the paint evenly with a rod (iron rod or wood rod) and lift it to a height of 20cm to stop for observation. If the paint solution does not line in a short time (a few seconds), it is too thick; If the line breaks as soon as it is away from the top edge of the barrel, it is too thin; When you stop at a height of 20 cm, the paint liquid will form a straight line and flow into drops in an instant. This viscosity is more appropriate

2. The air pressure is best controlled at 0.3-0.4 MPa (3-4 kgf/cm2). If the pressure is too small, the paint liquid atomizes poorly, and the surface will form pits; Excessive pressure is easy to flow and hang, and the paint mist is too large, which not only wastes materials but also affects the health of the operator

3. The distance between nozzle and object surface is generally 300-400 mm. Too close to easy to hang; If the paint mist is too far away, it is uneven, prone to pitting, and the nozzle is far away from the surface of the object. The paint mist flies away on the way, causing waste. The specific size of the distance should be appropriately adjusted according to the type of paint, viscosity and air pressure. The spraying distance of slow drying paint can be a little farther, and the spraying distance of fast drying paint can be a little closer; When the viscosity is thick, it can be closer, and when the viscosity is thin, it can be farther; When the air pressure is high, the distance can be farther, and when the pressure is small, it can be closer; The so-called closer and farther means a small range of adjustment between 10mm and 50mm. If it exceeds this range, it is difficult to obtain an ideal paint film

4. The sequence of spraying is: difficult before easy, inside before outside. High place first and then low place, small area first and then large area. In this way, the spray paint will not splash on the sprayed paint film and damage the sprayed paint film

5. The spray gun can move up and down, left and right. It is best to operate evenly at a speed of 10-12 M/min. the nozzle should be straight to the surface of the object for spraying, and oblique spraying should be minimized. When spraying on both ends of the object surface, the hand that pulls the trigger of the spray gun should be loosened quickly to reduce the paint mist, because both ends of the object surface often need to be sprayed more than twice, which is the place most likely to cause sagging

6. When spraying, the next layer should be pressed against 1/3 or 1/4 of the previous one, so as not to miss spraying. When spraying quick drying paint, it needs to be sprayed in sequence at one time. The effect of supplementary spraying is not ideal

7. When spraying in an outdoor open place, pay attention to the wind direction (it is not suitable to work in strong winds), and the operator should stand in the downwind direction to prevent the paint mist from being blown by the wind to the sprayed paint film, causing an ugly granular surface

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