Guidelines for the Use of Water-borne Paint Spray Guns

In recent years, with the enhancement of people's awareness of environmental protection and health, more and more water-based paints have been used. Water-based paints have gradually replaced paints in the home decoration and industrial fields, and become the mainstream of the market. When using water-based paint, spray gun is an indispensable tool. The main principle of spray gun is to compress the air by air compressor, and then spray out through the air cap at the front of the spray gun. A low pressure area lower than the atmospheric pressure is generated in the front of the paint spray nozzle connected with it. The pressure difference produced by the nozzle sucks the paint out of the paint tank and sprays particles on the surface of the coating under the action of high-speed jet force of compressed air. 

The air pressure should be controlled at 0.3-0.4 MPa (3-4 kg force/square centimeter). If the pressure is too low, the paint atomization is not good, the surface will form pits; if the pressure is too high, it will easily hang, and the paint fog is too large, which will waste materials and affect the health of operators. The distance between the nozzle and the surface is generally 300-400 mm. It is easy to hang near, uneven paint fog far away, easy to appear pockmarks, and paint fog far away from the surface of the nozzle will cause waste in the way. The specific size of the distance should be adjusted according to the type of paint, viscosity and air pressure. The spraying distance of slow-drying paint can be far, that of quick-drying paint can be close, that of viscous paint can be close, that of viscous paint can be far, that of air pressure can be far, that of pressure hour can be close, that is, the so-called near-point-far point 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.

The spray gun can move up and down, left and right. It is better to operate uniformly at a speed of 10-12 m/min. The spray nozzle should be straight to the surface of the object, and oblique spraying should be minimized. When spraying to both ends of the object surface, the trigger of the spray gun should be loosened quickly to reduce the paint mist, because the two ends of the object surface often have to accept more than two sprays, which is the most likely place to cause hanging.

When spraying, one third or one fourth of the previous one should be pressed down, so that there will be no leakage spraying. When spraying quick-drying paint, it needs to be sprayed in sequence at one time. The effect of supplementary spraying is not ideal.

When spraying in open outdoor areas, attention should be paid to the direction of wind (not suitable for operation in strong wind). Operators should stand in the direction of downwind to prevent the paint mist from being blown to the granular surface which has been sprayed. The order of spraying is: first difficult, then easy, first inside and then outside. First high and then low, first small area and then large area. In this way, it will not cause the spraying fog to splash onto the sprayed paint film and destroy the sprayed paint film.

Specific cleaning methods:

1) Close compressed air, remove the paint tank, pour the paint back into the paint tank, and pour the paint into the container;

2) Pour about 1/4 volume of solvent into the paint tank for washing, install the paint tank, connect the compressed air, and rock and roll spray several times;

3) Remove the spray head and clean it with solvent and wipe it off; Paint on gun body.

When cleaning spray guns, the following points should be noted:

1) Soft brushes should be used in cleaning, metal brushes should not be used, hard objects should not be used to poke and scrape, wear nozzles should be prevented, and jet shape should be changed;

2) Spray guns should not be directly soaked in solvents to prevent residual coatings from adhering to the parts and dissolving lubricants on the guns, and soft cloth with solvents can be used to wipe;

3) The knurling parts on guns are adjusted by hand to avoid the use of pliers;

4) Drop lubricating oil regularly at needle valves and pin shafts of guns;

5) Use light grease or vaseline lubricating needle valves and needle valve springs regularly, and do not use silicon-containing oil.