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If you’re lucky enough to have access to an HVLP spray gun set up, you’re probably eager to learn how to use it. These powerful machines make many projects possible, once you know how to handle them. In this guide, we’ll cover when to use an HVLP spray gun, the four phases of using an HVLP spray gun, and even give you some tips for the best HVLP spray gun techniques.
When to Use an HVLP Spray Gun
HVLP spray guns can be used to spray finishes onto a variety of surfaces, including wood, metal, glass, and some plastics.
One of the best things about HLVP spray gun systems is that they can handle both large and small projects. The best HVLP spray gun for woodworking allows you to stain or spray finish, while top HVLP guns can handle painting as well.
HVLP spray guns are appropriate to use anytime you want great results quickly.
They are frequently used by furniture makers and cabinet installers to get perfect results in a minimal amount of time. They can be used to paint home interiors and exteriors, and are capable of applying stain or finish to decks and fences.
HVLP sprayers can also be used for automotive work, including detailed and decorative painting or the application of clear coats.
They are able to apply smooth, even coats of finish quickly thanks to the phenomenon of atomization.
When an HVLP spray gun is connected to a source of pressurized air, pulling back slightly on the trigger starts the flow of pressurized air. Pulling the trigger back further causes the fluid needle to pick up liquid finish from the paint cup. When the finish is ejected from the nozzle of the spray gun, it meets the stream of pressurized air and becomes atomized.
Each of the atomized paint particles is very similar in size and weight. When they settle on the surface, the result is the smooth finish HVLP spray guns are known for.
Four Phases of Using an HVLP Spray Gun
When spraying with an HVLP gun, you can’t just pour in paint and pull the trigger.
First, whatever finish you use must be properly prepared. Then, you must adjust the controls until the spray and spray pattern are to your liking. Next, you apply the finish. Finally, HVLP spray guns must be thoroughly cleaned at the end of every work session.
Phase One: Preparing the Finish
Adequately thinning your finish is key to success when using an HVLP spray gun.
- Check the viscosity requirements of your spray gun. These should be listed in the materials that came with your gun, or you can find them online.
- Determine the appropriate thinner. For waterborne finishes, thin with water. For oil-based finishes, mineral spirits or paint thinner can be used. Check the label of your finish for specific thinner recommendations.
- Check the viscosity of your finish. Dip a viscosity cup in your unthinned finish, pull it out, and count the seconds until there is a gap in the flow of the fluid. If the viscosity is within the range recommended by your HVLP spray gun manufacturer, you do not need to thin it. If it’s above the range, move to the next step.
- Thin by 10% and check the viscosity again. Make sure to use a clean container for mixing finish and thinner. If the finish is still too thick, thin by another 5%. Keep going until you reach the right consistency.
- Record your recipe. Make a note in your phone or in a notebook of exactly how much you thinned the finish, and what you used to thin it. You’ll want to be able to replicate your recipe in the future if it performs well, or know what to adjust if there are problems.
Phase Two: Adjusting the HVLP Spray Gun
HVLP spray guns require fine-tuning to get optimal results.
- Practice on cardboard. No matter what finish you’re applying, removing it isn’t a simple prospect. Never approach your workpiece with an HVLP spray gun until you’re confident in the way it’s performing. Until then, scrap pieces of cardboard are great for checking your spray volume and spray pattern.
- Add your spray medium. Fill the paint reservoir with your chosen finish, making sure it is appropriately thinned. Double-check that the size of your fluid needle is appropriate for your finish. Make sure the fluid tip is large enough to accommodate your fluid, especially if you’re spraying something heavier-bodied such as latex paint.
- Spray the finish on the cardboard. Adjust your spray gun to the manufacturer’s recommended settings, and squeeze the trigger to start the spray. Observe the finish as it exits the gun, as it moves through the air, and as it hits the cardboard. Release the trigger.
- Adjust the gun. If the spray pattern is too wide, tighten the fan volume control knob. If it’s too narrow, loosen this knob. If your finish looks uneven, like an orange peel, check that there is no air getting into the system through loose connections or worn hoses. If the finish is dribbling out of the gun, you may need to increase the pressure or loosen your fluid control knob.
Phase Three: Spraying the Finish
Follow these steps each time you spray with your HVLP gun.
- Squeeze the trigger to start the flow of fluid. Make a long, sweeping pass, starting in one corner of your workpiece and moving to the opposite end. Release the trigger.
- Evaluate your results. If the finish was appropriately thinned and you used good technique, you should see a thin, even coat of your chosen finish.
- Keep going. As long as you’re happy with your results, you can keep spraying. Move your gun over so that the next spray will just barely overlap the first. Repeat until the entire surface is coated.
- Wait. Different finishes have different dry times. Lacquer is ready for a second coat within about 15 minutes. Waterborne finishes take an hour or two to dry when sprayed. Oil-based finishes take longer, about six hours minimum.
- Recoat. When the first coat is adequately dry, recoat as necessary.
Phase Four: Cleaning the HVLP Spray Gun
Cleaning is an essential part of using an HVLP spray gun and must be done immediately after use.
- Plan time to clean. Cleaning your HVLP setup shouldn’t take more than 15 minutes once you’ve got the hang of it. Not only can dried finish damage your HVLP spray gun, getting it off is a pain. Make sure to dedicate time for cleaning at the end of every work session while the finish is still wet in your gun.
- Rinse with solvent. With the spray gun disconnected from the air source, swirl solvent around the paint cup and spray it through the gun. Use water for waterborne finishes and mineral spirits for oil-based finishes.
- Disassemble the gun. Remove and soak all the spray gun components in solvent: spray tip, air cap, and fluid needle. Soak the nozzle of the gun as well.
- Scrub. Use a bristle brush to remove all residue from all surfaces of the gun.
- Wipe. Wipe all parts of the gun with a solvent-dampened rag.
- Dry. If water was used, wipe everything with a quick-drying solvent to prevent corrosion. Leave the parts to dry before reassembly.
HVLP Spray Gun Technique
The right finish and correct settings aren’t all you need to get a great result from your HVLP spray gun. You also need good technique.
- Use the right distance. HVLP guns should be operated six to eight inches from the surface you are coating. Maintaining this distance will give you even coverage and minimize overspray.
Note that conventional spray guns are used a bit further away from the surface — eight to ten inches. If you are used to spraying with a conventional gun or just learning how to spray, check your distance frequently using a ruler.
- Keep your arm straight. A slight bend in your elbow will help keep your arm from getting tired. Maintaining a uniform distance from the surface you are spraying is an important component of getting great results. Leaving your arm out straight while spraying helps you keep that spacing consistent.
You can use a horizontal or vertical spray pattern, whichever makes sense for your project.
- Consider the grain pattern when spraying wood. If you are spraying finish on wood, you should spray the first coat across the grain. Subsequent coats of finish can be sprayed in the same direction as the grain.
- Spray ‘off’ when possible. When painting walls and ceilings, you don’t have the option to keep spraying — you need to try to release the trigger at just the right moment. For smaller pieces, you’ll get a more even finish if you keep spraying until you clear the edge of the workpiece and then release the trigger.
An HVLP spray gun can be used to achieve great-looking finishes. The finish must be properly thinned to avoid clogging the gun and for atomization to occur. Using proper spray technique is also an important consideration when spraying with an HVLP gun. For the best results, test your HVLP set up on a piece of cardboard before spraying your workpiece.