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CNKS
01-30-2007 18:53:32
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Re: Paint Blotching in reply to SproutW, 01-30-2007 07:57:18
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The max pressure is stamped on the gun, or in the accompanying instructions. Set that pressure according to a gauge mounted on the gun, and do not change it -- that is the way the gun is supposed to operate, and unless you change the size of the pattern (a bad idea) it never needs to be changed. Before putting paint in the gun: Turn the fluid control almost all the way out. Then pull the trigger and turn the fluid control in until resistance is felt on the trigger. Turn in no more than 1/2 additional turn. Set the pattern control 1/4-1/2 turn in from wide open. If the gun is clean, that will give you the correct pattern, you will never need to mess with it. The gun should be held 6 inches +/- very little from the surface. The gun should be moved relativey slowly -- that he will have to experiment with. If he is using quality paint, meaning PPG/DuPont, etc, the mixing instructions are very precise and he does not need to deviate at all from those instructions. If you are using tractor store paint, i.e. alkyd enamel, that is thinned between 4:1 and 8:1 paint to reducer, likely much closer to 4:1. I cannot give an exact figure because I don't use that kind of paint. Sounds to me like the pressure is too high, gun is held too far from the surface, gun is moved too fast, paint is too thin, reducer (thinner) is too "hot" for the temperature, wrong reducer or thinner, temperature much too low (65-70 is ideal), or any combination of the above. Make sure the primer is compatible with the topcoat (use the same brand), clean the surface with wax and grease remover, not paint thinner or gasoline, or anything else. Do that and he should get an acceptable finish that will improve with experience.
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