How to Adjust a HVLP Spray Gun

HVLP (High Volume Low pressure) spray guns use a very high volume of air which atomizes paint at low pressure. These guns are very useful for reaching surfaces that may be difficult to target with other types of spray guns as well as spraying a larger amount of paint.

You will often see these guns being used on automobiles as they can spray large surface areas very quickly. They are also used on other specialized materials that require wider paint coverage.

If you are planning a project but need to adjust your HVLP spray gun, there are some key aspects you should consider.

The following article is going to guide you through the steps of adjusting your spray gun and setting it up for your desired use.

Setting Up Your HVLP Spray Gun

Every time you use your HVLP spray gun, you will need to set it up properly. If you ignore this initial setup process, the gun’s results could be quite poor.

Here is how to set up your HVLP spray gun:

  1. Use some masking paper and tape it to the wall
  2. Locate your gun’s inlet and set the pressure using the regulator
  3. With the air volume still pulled, ensure the control knob air volume is still closed
  4. Now, open the fan control knob. Usually, when the gun is around 6 inches away from the surface you intend to spray, the fan should be around 6 inches tall
  5. Turn the material knob and then aim the gun at the masking paper on the wall with the gun about 6 inches away from the wall
  6. Pull the gun’s trigger but only for a second. Holding down the trigger any longer can negatively affect the end result
  7. Looking at the masking paper, you should see a cigar-shaped pattern emerge which should be about 9 to 10 inches long. The center’s coverage should be full and fade away toward the edges
  8. If the pattern isn’t as it should be, such as too much density on the edges and not in the center, it usually means your airflow is too high. Simply screw down the material knob a little more to reduce the airflow

You may be unsure of your spray gun’s correct pressure levels or cubic feet per minute (CFM). If so, you just need to check your gun’s directions and they should tell you whether the air pressure you’re using is powerful enough.

If the air pressure needs changing, you can adjust it using the regulator located on the base of your spray gun. Just ensure you use an air dryer to keep the lines completely dry.

Adjusting a HVLP Spray Gun

When adjusting a HVLP spray gun, you need to understand 3 vital aspects. These are:

  • The air pressure
  • The fan pattern
  • The fluid volume

The Air Pressure

The air pressure of your spray gun correlates to the strength of the air that pushes out the paint. The majority of painting projects require air pressures between 18 and 25 psi for optimal results.

HVLP spray guns usually have a gauge that allows you to control the air pressure you desire. This gauge allows you to read the air pressure so you can fine-tune it as you go.

Furthermore, the hose that connects the air compressor to the spray gun can have an effect on the amount of pressure depending on how long or short it is.

The Fan Pattern

Another knob found in HVLP spray guns can also be adjusted but this is to adjust the fan pattern. By moving this knob, you can widen or narrow the paint coverage to get your desired result.

For larger painting jobs, such as automobiles or constructions, wider patterns are the best option. Smaller projects, on the other hand, will require narrow patterns. This will limit the chances of overspray and prevent any premature drying in certain areas.

The Fluid Volume

You can adjust or even stop the flow of paint coming out of your HVLP spray gun. This is done by adjusting certain nozzles on the gun.

If you’re unhappy with the paint’s spray pattern, you most likely need to adjust this nozzle. Thicker coats occur when larger amounts of fluid are ejected from the spray gun.

If you need to stop the flow of paint altogether, you can turn the nozzle fully in one direction and it will essentially block the flow of paint completely.

Testing

Once your spray gun is set up and adjusted, you need to ensure it is spraying accurately. You can do this through testing but there are some conditions that need to be met in order to do so.

Firstly, hold your gun about 6 inches away from the surface on which you’re going to paint. Hold down the trigger for a second or less. This will give you an accurate reading of your gun’s setup.

As we mentioned, as soon as you see that cigar-shaped pattern on the surface, with full coverage in the center and a gradual fade toward the outer section, you will know the gun has passed the test.

Common Issues

There are some common issues if you’re having trouble getting your spray gun set up correctly.

Firstly, you should check if your airflow is right. Adjust the gun if there is too much or too little airflow coming through.

Secondly, find out if your paint material is the right thickness. If the paint material is thick at the edges but thin in the middle, you probably have an airflow issue.

Another common fix is to check whether you’re holding your gun in the correct position. Stand about 6 inches from the surface. If you get too close or too far, the pattern will not work out as intended.

Lastly, you may be spraying too much paint. If this seems to be the problem, screw the material knob a little or turn the air pressure down.

Check all of these until you have achieved a smooth consistency on your test paper.

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