HVLP painting gun question

[Soundguy]

I have noticed the cheaper hvlp guns do use a lil more air than a high dollar hvlp.. almost as much as a syphon gun.. maybee 15 psi less... however... they still make less overspray and DO put alot of paint on target. a syphon gun can't touch the amount of paint on target that a hvlp layes down.

only thing i've seen that lays more paint is a pressure pot gun..

soundguy

 

[Car Doc]

Sound guy,

I have a regulated air supply in my paint booth but I still use a reg on my guns and the un-regulated supply line while I am in there.

I have found the reg on the gun is so much better control of the spray pattern as long as it is a good working one. I have a bad one on my clear coat gun right now I am probably going to throw it as far as my bad shoulder will let me next time I use it.

I think its a matter of hose flex when I let off and get back on or something that allows the pressure to fluctuate but I can very definitely tell the difference. as always ymmv

With that said a 17 dollar reg is a 17 dollar reg same as a 17 dollar hvlp gun does it compare to a $450 Sata or Binks no heck no its not meant to.

 

[Jay4200]

I have used these guns a couple of times now too, but I found that I had to set the regulator to 35 to 40 psi to get the gun to work properly. Not sure why they are called HVLP. :confused2:

I was wondering the same thing - I saw a poster giving a review give the same 35-40psi numbers (which puts it well into compressor-regulator territory). OTOH, it certainly isn't the 90psi or so that the siphon guns evidently need...

One thing I learned (after blowing through a gallon of paint at about 3% transfer efficiency) was that the paint transferred better with higher pressures. I expected the opposite and kept turning it down - I figured the crappy transfer was the way it was. I wouldn't have ever figured it out, except I turned the pressure up way up by accident, and the paint suddenly started go actually go onto the metal instead of just foofing off into the atmosphere. Once I cranked the pressure up, the transfer was pretty good. The second gallon covered 3-4 times what the first did. Unfortunately, I don't remember exactly what pressures I was running, but I think it was up near 90 - it was a few years ago.

JayC

 

[Soundguy]

that's kinda my point..it's a 17$ gun.. thus a cheap reg is about all ya need

i've always found having a reg on the gun effects me moving the gun due to stiffness of the hose past that. but as another member said. That's likely more of a personal choice issue.

soundguy

Sound guy,

I have a regulated air supply in my paint booth but I still use a reg on my guns and the un-regulated supply line while I am in there.

I have found the reg on the gun is so much better control of the spray pattern as long as it is a good working one. I have a bad one on my clear coat gun right now I am probably going to throw it as far as my bad shoulder will let me next time I use it.

I think its a matter of hose flex when I let off and get back on or something that allows the pressure to fluctuate but I can very definitely tell the difference. as always ymmv

With that said a 17 dollar reg is a 17 dollar reg same as a 17 dollar hvlp gun does it compare to a $450 Sata or Binks no heck no its not meant to.

 

[Car Doc]

Yup and like you and a few others have said a good paint job its more in prep than paint gun anyway at that point its operator skill how he makes the paint go on not with what. :thumbsup:

 

[bjr]

I have the HF HVLP gun and like it just fine and I'm just a guy that tries to paint some implement about once or twice a year. I've painted my propane tanks as well. What catches me every time I go paint is the orifice section in the gun where the main needle goes is always plugged with hardened paint. Yes I try to clean the gun after every use. I get the paint to flow and do okay then but still get a lot of runs. bjr

 

[ray66v]

I have used these guns a couple of times now too, but I found that I had to set the regulator to 35 to 40 psi to get the gun to work properly. Not sure why they are called HVLP. :confused2:

Like many things in the refinishing industry, the name and the wording are confusing.

The low pressure aspect is at the output of the air cap. A professional HVLP gun will put out about 10-12 psi at the cap, with 30-50 psi going into the gun

Most HVLP guns do a very poor job of atomizing the paint if you do not run them at high input pressures. If you don't atomize the paint, it generally won't lay out real flat, and you can have problems like solvent popping with automotive finishes.

It's not an airless. They still can make lots of over spray at those pressures, due to the volume of material transferred, forget the no over spray myth. The best way to reduce over spray is to learn to apply paint on the item your painting, and not the air. This means finding the correct distance, learning to control the trigger, and aiming properly. With practice, your transfer rate will increase.

A good rule of thumb when determining the best pressure for a given gun is: With material in the gun, open the fan control all the way and spray the gun into the air. While spraying, increase the pressure until you see the spray pattern, (we call it the fan), go from a nice oval to a distorted shape, decrease the pressure until it goes back to a nice oval. Note the pressure at that point. This is usually the pressure that will give you the best atomization with that gun, which will usually result in the nicest paint job.

Gravity feed HVLP guns are designed for applying high solids automotive materials. If you are spraying other products, you can actually use a traditional spray gun, make less over spray, and do a great job.

 

[Soundguy]

I have the HF HVLP gun and like it just fine and I'm just a guy that tries to paint some implement about once or twice a year. I've painted my propane tanks as well. What catches me every time I go paint is the orifice section in the gun where the main needle goes is always plugged with hardened paint. Yes I try to clean the gun after every use. I get the paint to flow and do okay then but still get a lot of runs. bjr

you pretty much have to clean the gun fully after each use.. down to spraying on a white cloth till no more color shows int he napth running thru it.. then wipe down exterior and clean cup too.

runs are bad technique, too thin of paint, or too much paint ( and 5 other things too ).


soundguy

 

[Jay4200]

Gravity feed HVLP guns are designed for applying high solids automotive materials. If you are spraying other products, you can actually use a traditional spray gun, make less over spray, and do a great job.

Are you saying that will a thinner paint, a regular gun will have better transfer efficiency? I suspect I'd be spraying low-cost oil-based paint, such as Rustoleum enamel.

Is it even possible to properly prep a surface without a sandblaster? I'd like to avoid using one, but wonder if I'm just wasting my time.

JayC

 

[ray66v]

Are you saying that will a thinner paint, a regular gun will have better transfer efficiency? I suspect I'd be spraying low-cost oil-based paint, such as Rustoleum enamel.
JayC

You can spray industrial enamel like Rustoleum with any kind of gun, you would have to reduce it to the right viscosity.

House paint, and industrial enamel are a little on the thick side so they do spray better with a gravity feed gun, a pressure feed, or airless. These kinds of paint don't need to be atomized, so you can use a lower air pressure, and let them flow out. But, if you add enough reducer, you can spray them with an old siphon gun.

Lighter products that are mostly solvent, like: Lacquers, stains, varnishes, and acrylic enamel, will all spray better in a convention gun.

Is it even possible to properly prep a surface without a sandblaster?
JayC

Yes, no, and maybe. This depends on an awful lot of things.

Sandblasting an item of any kind of size requires a good sized compressor, a good air drier, and the right media.

If you sand blast it with crude basic equipment, you could end up blowing water vapor all over, and it could begin rusting before you even finish it.

There are lots of way to prep something for paint, from a simple cleaning and scuffing, to using a wire wheel on a grinder.