Paint is likely one of the most intimidating things consistent among all corners of the automotive world. It requires heaps of laborious preparation and the materials cost a ton, and that’s nothing to say of the mysterious device required to apply the stuff. I’ve yet to see a paint gun that so much as indicates the functions of its various knobs. There’s a sort of medieval appeal to the whole process; just as the ability to draw the sword from the stone confirmed the true king of England, somehow the ability to make sense of a gun’s knobs is innate to only those ordained to be painters.
Fortunately that’s just plain bull. Paint gun setup is not just within anyone’s abilities, it’s easy. What follows is one person’s setup technique.
We say one person’s because no two painters will exactly agree how to set up a gun. In fact, the method our pal Sam Ferguson presented is likely to infuriate other painters. Some painters are that way, you know.
But according to Ferguson this technique is a pretty foolproof method to set up nearly any gun for nearly any application. More than endorse it, he lives by it; Ferguson paints professionally.
Sam Ferguson starts by opening...
Sam Ferguson starts by opening the pattern-control knob (upper) and fluid-control knob (lower) all the way.
First, a few things. He’s an Iwata man but most of us laypeople can’t justify the expensive equipment he uses. So we had him show us his technique on the Eastwood gun we reviewed in the Aug. ’11 “Workshop.” Not that it matters, really; he maintains that every gun he’s used responds to this technique. In fact he said that he learned this technique when he began painting. And that was with older, high-pressure guns.
And we don’t want to hear about him not using a respirator. It’s because he didn’t need to this time; we conducted this exercise with Auto Air Color’s non-toxic water-based paint. Were he to shoot conventional paint he’d don a paint suit, respirator, gloves, and so forth. And so should you; isocyanate in modern paint won’t just get you high; it’ll make you nearer your god to thou, so to speak.
What follows isn’t enough to make one a good painter; however, it’s a good first step. And while it won’t match every other method out there, it does in fact work as I witnessed. Follow it, and there’s no reason it won’t work for you too.
The air control valve (upper,...
The air control valve (upper, blue knob) governs the air pressure to the gun. The external regulator (below) does the same thing but offers finer adjustment and makes accurate documentation possible.
Ferguson recommends holding...
Ferguson recommends holding the gun so the cap is roughly 8 inches away from the subject. He recommends pulling the trigger fully in one smooth, fluid motion. Pull too quickly and the pattern won’t develop; pull too slowly and the pattern will likely load up and possibly run.
If using an external regulator...
If using an external regulator Ferguson says to open the gun’s air-control valve all the way (blue knob from last step) and set the regulator pressure at roughly 50 psi. Bear in mind that the pressure rating on the spray cap refers to the pressure at the cap, which is considerably less than the inlet pressure.
If not using an external regulator,...
If not using an external regulator, Ferguson says to close the gun’s air-control valve lightly and open it two-and-a-half turns. Again, this is simply a baseline setting. Additionally, he recommends setting the regulator on the compressor to no more than about 60 psi.
A pattern should apply paint...
A pattern should apply paint consistently over an 8-inch-long span in Ferguson’s estimation. He maintains the pattern should cover fully at the center and taper smoothly in both width and density toward the ends. Incidentally the gun achieved this pattern with Ferguson’s baseline settings (pattern- and fluid-control knobs open fully and the air-control valve opens two-and-a-half turns).
Ferguson reduced the air inlet...
Ferguson reduced the air inlet pressure to show how the gun sprays with insufficient air inlet pressure. Even though he maintained his 8-inch working distance the pattern shrank to about 4 inches long. As the paint can’t atomize properly at these low pressure settings it will also transfer in fat globules rather than in a fine mist. Increase the pressure to achieve the correct pattern.
The fluid-control knob is...
The fluid-control knob is nothing more than a trigger stop. Turning it clockwise simply prevents the trigger from opening fully. Until now we’ve left it fully open to make the largest pattern possible.
Excessive air inlet pressure...
Excessive air inlet pressure will create a pattern longer than 8 inches despite the same ideal 8-inch operating distance. It can also apply too much paint, which may readily run. Very excessive pressure can also generate a dumbbell-shaped spray pattern like this. Reduce the air-inlet pressure to achieve the correct pattern.
Turning the fluid-control...
Turning the fluid-control knob clockwise (in) restricts air and paint flow proportionally. That reduces the pattern’s overall size and density yet doesn’t alter its longish tapered shape. According to Ferguson, reducing the pattern size and density helps blend repairs.
Holding the gun too far away...
Holding the gun too far away from the subject will also increase the pattern size. His hand obscures part of the pattern but it’s visibly longer than the 8-inch-long pattern he achieved earlier. Excessive operating distance also results in a “dry” spray, the prime culprit for dull or orange-peel surface finish.
The fan-control valve (above...
The fan-control valve (above the fluid-control knob) alters the length of the pattern but not its width. Turning it clockwise turns the longish, tapered pattern into a shorter, round one. Ferguson maintains the fan-control valve has great utility when painting very small parts or complicated shapes.