What Is a HVLP Spray Gun?

Considering the purchase of an HVLP spray gun? You’re in the right place. This article starts by defining ‘HVLP’ and explaining how these spray guns work, before delving into the different parts of the gun. By the end, you’ll be able to identify what is a HVLP spray gun, know what they are used for, and understand why they are known for producing low overspray.

What Does HVLP Mean?

An HVLP spray gun is a specialty tool used to apply paint and other finishes. HVLP is an abbreviation for ‘high volume, low pressure’.

• A high volume of air is used to prepare paint and other substances for application with an HVLP sprayer.
• The air that is used to turn liquid into a sprayable mist leaves the gun at a lower pressure than a conventional-type spray gun.

How Does an HVLP Spray Gun Work?

The pressure used to power HVLP spray guns can come from one of two places; an onboard turbine unit or a seperate air compressor. An air hose is used to connect the gun to the source of pressurized air.

The air is then fed through the machine in a controlled fashion, as paint or another finish is drawn through the spray gun. The fluid and air meet just outside the tip of the HVLP spray gun and form a fine spray.

This spray, which is called ‘atomization’ is what makes HVLP spray guns so sought after and effective. When the different variables are set correctly, the top rated HVLP spray guns produce coverage of unmatched evenness, with no brushstrokes or roller marks.

HVLP Spray Gun Uses

HVLP spray guns are fast, accurate, and reliable. They produce a super smooth finish in a short amount of time, with a minimum of overspray.

• The Cabinet makers and the furniture makers use HVLP spray guns in their shops or on-site to produce perfect, even finishes.
• Automotive body shops use HVLP spray guns to apply lacquer and paint and do specialty design work.
• HVLP spray guns can coat an average living room wall in about five minutes, so they are popular with both interior and exterior painters. 
• They are appropriate for both large and small projects and can handle detail work with little overspray.
• HVLP spray guns can be used to spray stain, lacquer and other wood, varnish for spray (including polyurethane for spray), clear coats, and paint.
• Heavier-bodied finishes such as latex paint must be thinned before they can be sprayed using an HVLP system.

What Are the Parts of an HVLP Spray Gun?

The spray gun itself has complex inner workings governed by exterior controls.

Trigger

Usually similar to the trigger of a garden hose, when you first squeeze the trigger of an HVLP spray gun, all you get is air. Pull back further and (if everything is set up correctly) you’ll get a fine, even mist of finish.

Fluid Chamber

On top of an HVLP sprayer, there is a container to hold fluid. This is sometimes called the paint cup or the fluid reservoir.

Fluid Needle

The fluid needle sits below the fluid chamber and leads through the air cap to the spray tip of the HVLP spray gun.

Fluid needles come in different sizes, with larger needles being used for heavier, thicker-bodied fluids. The fluid needle is held in place by packing, secured with a packing nut.

The path of the fluid needle can be adjusted by turning the fluid volume control knob, which is usually located to the rear of the spray gun, in line with the nozzle.

The paint (or other finish) flows through the needle and out the nozzle of the spray gun, where it meets with a steady flow of pressurized air and turns into a fine spray.

Air Cap

The air cap is installed over/around the fluid needle. Each fluid needle has an appropriately sized air cap. It is generally recommended to use the air cap that came with your fluid needle. However, when spraying heavier bodied materials, switching to a larger air cap can improve atomization.

Spray Tip

Spray tips control the fluid as it exits the spray gun. Along with the fan control the spray tip shapes and directs the pattern of the spray. Larger spray tips are used for thicker finishes and smaller spray tips are used for thinner finishes.

Control Knobs

The three knobs are used to control the variables on an HVLP spray gun. They are: the fan control knob, the fluid volume control knob, and the air volume control knob. Each knob can be tightened or loosened to change the way the spray gun operates.

Maintaining an HVLP Spray Gun

HVLP sprayers require minimal maintenance. After every use, they must be thoroughly cleaned. Paint or other finish should never be allowed to dry on or inside an HVLP sprayer. Instead, you must use an appropriate solvent (usually water and soap; or mineral spirits substance) to remove all the excess finish.

A drop of lubrication is needed when changing the fluid needle. The joints and seals should be maintained, like any machine, but HVLP spray guns can last for a long time when properly cared for.

HVLP Spray Guns and Overspray

No article about HVLP spray guns would be complete if it didn’t touch on overspray.

When spraying paint (or any finish) some of the atomized finish particles are going to settle on surfaces other than the one you were trying to coat. This is called ‘overspray’.

Conventional spray guns produce a significant amount of overspray, leading to environmental concerns about their usage. HVLP spray guns, on the other hand, are known for the minimal amount of overspray they produce.

Because HVLP spray guns spray liquid at a much lower pressure, the particles of finish are moving fairly slowly when they meet the surface to be coated. This helps the particle to cling to the surface instead of bouncing off of it and floating off in the air to settle somewhere else.

Overspray is a fact of life when spraying – all you can do is minimize it and cover your belongings with plastic sheeting.

Conclusion

HVLP spray guns are used to apply finishes to a variety of surfaces. They are known for their low overspray and smooth, even finish. HVLP spray guns have a number of moving and removable parts and must be connected to a source of pressurized air. They require minimal maintenance beyond prompt cleaning at the end of every use.