When I visit plants for a tune up in their spray shops, I almost always notice one thing. Painters using air spray guns have their gun atomization air pressure turned up way too high. I often see it turned up as high as it will go. For most plants, that’s about 120 psi. This is especially true in shops with lots of painters and high turnover. Everybody wants high production rates, and that includes painters. Pulling the trigger with high air pressure gives the feel of power, speed, and high productivity. Who wouldn’t like that?
Before anyone gets addicted to high air pressures, let’s ask ourselves one question. Where does that air go when it leaves the gun?It goes into the air, because it’s air. But the goal of painting is to get paint onto the parts, not into the air. Too much air takes the paint that you want on the part and puts it into the air. More air pressure equals more overspray. Less air pressure equals less overspray, greater productivity, lower paint usage, lower VOC’s, and reduced filter usage.
So how do you set the air correctly on an air spray gun with a pressure pot?
Remember, more air pressure isn’t necessarily good. In fact, it’s usually bad. I recommend that paint shops keep records of the best fluid pressures, air pressures, and appropriate amounts of thinner for each coating that they spray. It would be helpful if painters would follow the recommended guidelines. When there are too many cooks in the kitchen with no recipe, the air pressures usually go up and they stay up. That wastes a lot of time, paint, and money. Fortunately, this situation can be easily avoided.