Your Cart is Empty
September 17, 2026 4 min read
A spray gun really isn’t that complicated. You’ve basically got three things to work with: air pressure, fluid control, and fan adjustment.
The problems start when you begin turning knobs without understanding what each one actually changes.
Before worrying about gun speed, overlap, distance from the panel, or spraying technique, understand what the controls on the gun are actually doing.
Here’s the quick version. Now let’s break down what’s actually happening.
The regulator controls the air pressure being supplied to the spray gun.
That air helps break the material into fine droplets as it leaves the gun—a process called atomization.
Too little air can result in poor atomization and larger droplets. Too much air can create excessive overspray, bounce-back, and wasted material.
There isn’t one pressure setting that works for every gun and every material. Gun design, tip size, material viscosity, and the manufacturer’s recommendations all matter.
For now, the important thing to understand is what this adjustment does:
Air pressure affects how the material is atomized.
The fluid adjustment controls how far the needle can travel when you pull the trigger.
I like to think of it as a throttle stop.
With the adjustment wide open, the needle has its full available travel. Start turning the adjustment in and you begin limiting that travel—and therefore limiting how much material the gun can deliver.
I generally like to run my fluid adjustment wide open and control the material with the trigger. That gives me the full range of the gun when I want it.
That doesn’t mean everybody has to spray that way.
Restricting the fluid adjustment can be useful when you deliberately want to limit how much material the gun can deliver. The important thing is understanding what you're actually changing: you're mechanically limiting needle travel.
Turn it in: less available fluid.
Turn it out: more available fluid.
Since the fluid adjustment works by controlling needle travel, the needle itself needs to move smoothly and return properly.
If you've ever had a spray-gun needle start sticking or hanging up, I've got a separate video and article showing a simple product I use calledNeedle Juice and where I apply it.
Spray Gun Needle Sticking or Leaking? See How To Fix It Here
It's a small maintenance detail, but it can make a noticeable difference in how smoothly the gun operates.
The fan adjustment controls the width and shape of the spray pattern.
Turn the adjustment in and the pattern gets narrower. Keep going and eventually you can get something much closer to a concentrated, round pattern—what I describe in the video as shooting like a squirt gun.
Turn it back out and the pattern gets wider.
For normal panel work, you generally want a wide, even fan that lets you cover the panel consistently. A narrower pattern can also be useful when you're working in a confined area where a full-width fan isn't practical.
Here's the important distinction:
The fluid adjustment controls how much material the gun can deliver. The fan adjustment controls how that material is distributed.
Two different adjustments. Two different jobs.
Understanding these adjustments gets much easier when you connect each action with its consequence.
Action: Air pressure is set too low.
Consequence: Poor atomization, larger droplets, and a coarser finish that can contribute to excessive texture or poor flow-out.
Before blaming your spraying technique, make sure the gun is getting the air it needs.
Action: Air pressure is higher than necessary.
Consequence: Excessive overspray, material bounce-back, wasted product, and potentially a drier finish.
More air isn't automatically better.
Action: The gun is delivering material faster than you're moving or faster than the surface can handle it.
Consequence: Heavy areas, sags, or runs.
This is where understanding the fluid adjustment—and developing good trigger control—becomes important.
Action: The fluid adjustment is restricted too far.
Consequence: Not enough material reaches the panel, potentially resulting in a dry application, poor flow-out, or unnecessary additional passes.
If you're constantly fighting to get enough material out of the gun, look at the setup before automatically changing your technique.
Action: The fan is restricted too much.
Consequence: Material becomes concentrated into a smaller area, making it easier to create heavy spots and inconsistent coverage.
A narrow fan has its uses, but it should be intentional.
Action: The fan is wider than the job requires.
Consequence: You're distributing material over a larger area, which may make the gun less effective for the specific area you're trying to cover.
The right fan depends on the job.
Action: You adjust the gun and immediately start spraying the vehicle.
Consequence: The vehicle becomes the place where you discover the gun wasn't set correctly.
That's an expensive test panel.
A spray-out lets you see what the gun is doing before the material ever touches the vehicle.
This is one of the biggest things to understand.
If the gun isn't adjusted correctly, it's easy to start compensating with your hand.
You speed up. You slow down. You move closer. You move farther away. You change your overlap.
Now you've got several variables changing at once, and it becomes much harder to figure out what the original problem actually was.
Understand what the gun controls first:
Air controls atomization.
Fluid controls material delivery.
Fan controls the spray pattern.
Once you understand those three things, diagnosing what the gun is doing becomes a whole lot easier.
Knowing what the adjustments do is the first part.
The next step is setting up the gun, doing a spray-out, looking at the pattern, and making adjustments based on what you see.
I've got a separate demonstration showing exactly that process, and we'll cover it next.
For more automotive paint, bodywork, restoration, and hands-on shop tips, visit VTwinsToV8s.com.
Like our hands-on automotive content?
Add V-Twins to V-8s as a Preferred Source on Google.
Comments will be approved before showing up.
This site documents real builds, tools, and shop work from my own projects. Some pages are showcases. Some are how-tos and tool reviews. If you’re working on a project and want experienced guidance, I offer one-on-one coaching.