The best air pressure is … whatever pressure you like. That’s not really a smart-ass answer. Let’s let Lybecker, who has a background as a teacher and technical consultant, explain.
“Air pressure is the energy needed to move paint. Paint is resistant to being moved. So what you have to solve is the problem of air pressure versus viscosity. If your air pressure is too low, or your paint is too thick, you will get a grainy or splattery spray.
“I recommend starting at a low air pressure, 10-15 psi or .75-1 bar. You will most likely get a grainy spray. Increase the air pressure until the paint sprays as you want it. The higher the pressure, or the thinner the paint, the smaller the dots of paint and the more transparent or film-like the coverage. At a low psi or with thick paint, the spray will be grainier and less transparent. If you go too high with the psi you tend to get more overspray.
“Also, you may have to change the air pressure depending on the formulation of the paint. Colors like the blues and reds have relatively small amounts of solids in them. Colors like white contain more solids, so they have more resistance to flow.”
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