Seven operating skills for waterborne coating construction

Spraying method is one of the main methods in the construction of water-based coatings. When spraying method is used to paint the surface of the object, a thin and uniform coating film can be obtained, and the coating can be evenly distributed for different geometric shapes, small holes, gaps, and uneven places; For spraying large surfaces, this method is faster and more effective than brushing. However, it is also necessary to master some operating skills when using the spraying method for construction:

Use clean water to adjust the coating to the appropriate spraying viscosity, and measure it with the coat-4 viscometer. The appropriate viscosity is generally 20 seconds to 30 seconds. If there is no viscometer at the moment, visual inspection can be used: stir the paint evenly with a rod (iron rod or wooden rod), lift it to a height of 20 cm, and stop to observe. If the paint liquid does not line in a short time (several seconds), it is too thick; It is too thin if the line breaks as soon as it leaves the upper edge of the barrel. When staying at a height of 20 cm, the paint liquid will be in a straight line, and will break and flow into drops immediately. This viscosity is more appropriate.

Second, the air pressure * * should be controlled at 0.3~0.4 MPa (3~4 kgf/cm2). If the pressure is too small, the paint liquid will atomize poorly, and the surface will form pits; Excessive pressure is prone to sagging and paint mist is too large, which not only wastes materials but also affects the health of operators.

Third, the distance between nozzle and object surface is generally 300 mm~400 mm. When too close, the paint film is easy to flow and hang; If the paint mist is too far away, it is uneven and prone to pockmarks, and the nozzle is far away from the object surface, the paint mist will fly away in the way and cause waste. The specific size of the distance should be adjusted according to the type of coating, viscosity and air pressure. The spraying distance of slow-drying paint can be farther, and the spraying distance of quick-drying paint can be 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 low, it can be closer; The so-called "near and far" refers to a small range of adjustment between 10mm and 50mm. If it exceeds this range, it is difficult to obtain an ideal paint film.

Fourth, the spray gun can move up and down, left and right, * * to operate evenly at the speed of 10-12 meters/minute, the nozzle should be straight on the surface of the object, and the oblique spraying should be minimized. When spraying to both ends of the object surface, the hand that pulls the trigger of the spray gun should be released quickly to reduce the paint mist, because the two ends of the object surface are often subject to more than two times of spraying, which is the place where * * is easy to cause sagging.

Fifth, when spraying, the next layer should hold 1/3 or 1/4 of the previous layer, so that there will be no leakage. When spraying quick-drying paint, it needs to be sprayed in sequence at one time, and the effect of re-spraying is usually not ideal.

Sixth, when spraying in an open outdoor place, pay attention to the wind direction (it is not suitable to work in a strong wind), 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 and causing unsightly granular surface.

Seventh, the spraying sequence is: first difficult, then easy, first inside and then outside. First from high to low, and then from small area to large area, so as not to cause the spray paint spray to splash on the sprayed paint film and damage the sprayed paint film.