What Air Pressure for HVLP Spray Gun?

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HVLP spray guns use low pressure to spray paint (and other fluids) onto surfaces, providing smooth and even coverage with minimal overspray. But just how low is ‘low’? What affects the air pressure setting? Where should you set the air pressure? Learn the answer to these questions in the article below. 

Overview of Air Pressure in HVLP Spray Guns

First, you must understand the role that air pressure plays in spraying with an HVLP gun. 

A man holding homeright hvlp spray and adjusting the pressure settings
  • HVLP guns use pressurized air stored in compressors to atomize fluid. The fluid is then ejected it from the spray gun tip in a fine spray. 
  • The air pressure of an HVLP gun is expressed in PSI, or pounds per square inch. A regulator is used to set the air pressure before spraying, and to make adjustments during the spraying process. 
  • All air compressors come with regulators. However, you can also place a regulator at the base of your spray gun. Adjusting and monitoring the air pressure closer to the ejection site is helpful when making minute changes to the air pressure. 
  • When the air pressure is too low, your paint won’t atomize well. As particles of different sizes are flung towards your coating surface, the result is an uneven coat that resembles the peel of an orange. 
  • When the air pressure is too high, the paint exits the gun at a high velocity. Particles have the opportunity to bounce off of the surface you are trying to coat. Not only is this costly in terms of material wastage, you also have to deal with the overspray. 

What Air Pressure Should I Use for HVLP? 

When working with an HVLP sprayer, you should always start with the manufacturer’s recommended air pressure. This is usually between 25 and 30 PSI. 

There are two places to look for a recommendation on what air pressure to use while spraying an HVLP gun; the documentation that came with your spray gun, and the instructions on the back of the paint can.

In general, base coats are sprayed at a lower air pressure – between 25 and 27 PSI. Clear coats tend to respond best to slightly higher pressure – 28 or 29 PSI. 

However, the manufacturer’s recommendation can’t take into account certain other concerns. Depending on the conditions you’re spraying under, you may need to adjust the air pressure to get the results you’re looking for.

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A good HVLP spray gun should be sprayed well in a variety of conditions.

Factors That Affect HVLP Air Pressure

Three factors that affect HVLP air pressure requirements are; cold weather, the presence of thinner, and the length of the air hose. 

A man is using an HVLP spray gun to spatter the wood surface.

Cold weather

Liquids become thicker at colder temperatures. Thicker liquids are harder to atomize. You may need to raise the air pressure to compensate for some variation in temperature. 

Better yet, bring your paint, stain, or another finishing medium up to room temperature by bringing it inside the day before you plan to spray. 

Thinner

Many fluids must be thinned before application with a paint sprayer, to enable the spray medium to move easily through the gun. The manufacturer’s recommendation on the can of paint is for unthinned paint. If you have added thinner to your paint, be prepared to lower the air pressure slightly to get optimum results. 

Length of your air hose

As air travels through the hose to the gun, some of the pressure created in the compressor is lost. The longer the air hose is, the more significant this loss will be. 

If you’re using an ultra-long hose, it’s better not to crank up the air pressure. Instead, get a regulator that attaches to the other end of the hose, where the spray gun is. By adjusting the pressure directly before the air enters the gun, there is no opportunity for pressure to drop. Best of all, you can fine-tune the pressure without putting down the spray gun. 

Conclusion

The air pressure is an important component of an HVLP spray setup. Regulating the air pressure at the spray gun is more accurate than regulating air pressure on the compression tank. For most jobs, the PSI should be between 25 and 30. You may need to adjust the PSI depending on the weather, the fluid viscosity, and the length of the air hose. 

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Ellenkate grew up on job sites run by her family’s construction company. She earned her theater degree from The Hartt School, a prestigious performing arts conservatory in Connecticut. Her design and DIY work from her Chicago loft was featured in the Chicago Reader and on Apartment Therapy.