HVLP Spray Guns FAQ

Posted: July 24, 2015 By: Eastwood

What size compressor do I need to run this? How many PSI? How many CFM? – This will vary from gun to gun, and even with what tip you are using on the gun. For the most part HVLP guns need more air volume, and less air pressure than a conventional gun. Eastwood offers guns that use as low as 29PSI and 4CFM

What guns are good for clear coat? – Most guns good for general finish spraying are good for clear coat too. The important thing is to size the nozzle/needle properly for the viscosity of the paint so it goes on uniformly and with the proper thickness.

Which guns can spray water based paints? – Waterborne paints tend to cause more corrosion than oil based. Guns to spray these paint are either all stainless steel internally or have coatings to resist corrosion.

Why do I get streaks in my paint jobs? –
Streaks in the spray pattern, especially heavy bands at the outside edge, is an indication of low pressure at the tip. Turn up the pressure control knob until these bands are eliminated. If the sprayer is already at maximum, you may have to use larger diameter hose or shorten the length of the hose to reduce the pressure drop. Also, make sure any paint filters in the system are clean, because there will be a pressure drop across a restricted or plugged screen. Sprayers are rated for a maximum tip size. Using a tip that is larger than the maximum size or a tip that is worn larger will cause low pressure. The tip should also be the proper size for the type of material being sprayed.

What size needle and nozzle should I use? –
Although every job may have slightly different requirements, for most materials it is best to choose a mid-size, or No. 3, needle and nozzle. If your paint is thicker than standard oil-based enamel, you may want to consider a larger size. Remember that there is no one tip that is perfect for all jobs. Needles and nozzles are quick and easy to change out. So try different sizes until you find what works best.

Why does my gun spit a small stream of paint after I release the trigger? –
The cause of the problem is that the needle is not seating properly in the seat. You will need to either purchase a kit for the gun needle and seat or you may only need to clean the needle and seat assembly. Residue or debris may cause the needle to move off to the side before seating.

How often does a gun need to be rebuilt? How can I make it last longer? –
This depends on what material you’re spraying and how many gallons sprayed per day. For example, with lacquers, guns don’t need rebuilding as often because lacquers don’t have solids in them. In contrast, the high solids in blockfillers are abrasive and require more frequent gun rebuilding.

One way to increase gun life before repacking is to thoroughly clean your gun at the end of every day. Be sure to trigger the gun before removing the diffuser and when installing the diffuser. If you don’t, the diffuser will score around the ball on the new needle which can lead to premature wear. Your gun will develop a leak and this will cause spitting.

What is tip wear? How can I compensate for it?  –
Tip wear is gradual, usually over days or weeks. The operator will attempt to compensate by doing the following:

  • Increase fluid pressure (an attempt to achieve an acceptable pattern). This will increase fluid delivery even more.
  • Back away from the part (an attempt to achieve a larger pattern). This may result in a dryer spray pattern.
  • Increase gun speed (an attempt to prevent runs and sags).

Why do I get “Orange Peel” when spraying HVLP?
“Orange Peel” happens when the paint on the surface starts to dry before paint under it. The main causes are: Paint applied too thick due to too much or too little air pressure, paint viscosity too heavy for needle/nozzle, holding the gun to close to the painted surface and weather causing the paint to dry too fast.

What is the difference between conventional style spray guns, HVLP and turbine guns?
Conventional spray guns typically operate at 40- 60PSI out of the gun. Typically they atomize paint better, but loose more than 50% of the paint to overspray. HVLP guns use more air at a lower pressure usually around 10PSI. They produce a smaller spray pattern, and don’t atomize as well, but deliver nearly 70% of the paint to the surface. Turbine HVLP guns don’t use an air compressor. They have their own turbine based air supply to deliver higher volumes of air at lower pressures.

Why am I not getting a good paint flow at the tip? –
Is the tip plugged? Is the pressure set too low? Are the filters plugged? Is the paint too thick for the gun to spray easily?

What do the numbers 1.0, 1.2, 1.4, 1.8 mean? –
That is the size of the hole in the tip of the spray nozzle in mm. Larger holes are used for thicker paints, like primer. There is typically a corresponding sized needle for each size nozzle.

Where do you order repair and replacement parts from? –
Right here. Eastwood carries a full line of parts and accessories for all the guns we sell.

Do all these guns come with an air regulator with gauge? –
Not all of these guns include the regulator/gauge at the air inlet of the gun, but Eastwood sells them separately in both analog and digital gauge versions.

What are the signs of tip wear? –
Flow rate increases – As the tip wears, the physical opening in the tip increases. An increase from .015” to .017” (two one-thousands of an inch) may result in a 33% increase in flow rates. How quickly this happens  depends on the factors listed above.

Pattern size decreases – The tip will wear out in the top and bottom portions of the tip opening. This will result in a smaller pattern size. It will continue to decrease in size as the tip wears.

What parts of the gun need periodic lubrication? –
The fluid needle packing A, the air valve packing B and the trigger bearing screw C require daily lubrication with a non-silicone/nonpetroleum gun lube. The fluid needle spring D should be coated lightly with petroleum jelly or a non-silicone grease (i.e.. lithium). Lubricate each of these points after every cleaning in a gun washer.

Can I get different sized tips for these guns? –
Eastwood carries all the parts and accessories for all the guns we sell. If different sized tips, needles and air caps are available you can get them from us.

What sort of storage does this come with? Does it have a plastic carrying case? –
Many of the guns we sell do come in storage cases. We also carry an empty case specifically for DeVilbiss gravity feed guns.

What is the best general purpose HVLP spray gun?
What’s the difference and purpose between the DeVilbiss Starting Line and Finish Line? – The Starting Line series are designed to cost less and be more entry level friendly, but they still feature all DeVilbiss’ years of spray gun expertise and will give years of reliable service. The Finish Line series is a full on professional gun designed for years of heavy usage when your livelihood depends on it.

Which guns can use the DeKup system? –
Eastwood has adapters to fit the DeKups, Gunner and 3M PPS systems for most guns.

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