air pressure for painting

I am considering purchasing a LPHV mid ranged priced gun from supplier of auto parts in London Ont. near where I live.
What might be the initial air pressure for the first finish coat second (if necessary) and final coat
I will be using only one gun not a large quantity / volume type that costs $60.00 or more and not a touch up type that has a small nozzle.
The one I saw at the supplier was around $30 to $40.00.
For what I am doing it will probably last for a number of years if taken proper care of.
 
The air pressure would vary from gun to gun and paint to paint. Generally the thinner the paint the less pressure needed. Start with about 40 psi and see how it goes.
 
Most any compressor that has a 10 gal tank or bigger is likely to work fine since most paint guns use a low pressure system. But that said moisture in the compressed air is a very very big problem so you have to have something in the system to remove the moisture or the paint will not work very well
 
The nozzle tip needs to be 4.0 for what your doing.The paint manufacture should have listing for air pressure.What many people don't know is air pressure at the gun not the tank.A 10 gallon tank will never supply enough air delivery for a hvlp gun.Also the paint gun should list the cfm output the compressor needs to be to properly supply air to the gun constantly.
Tom
 
Dear Tom
The Gun I am looking at has the supply bottle above the gun handle not below it. I /maybe mistakenly/ understand that this type takes less air pressure to work properly than the syphon type with the supply bottle below the gum. Wm.
 
It can be confusing,The gun your looking at is the best way to go,but they use a lot of air.You need high pressure at the gun but you will get low pressure at the nozzle.Again look on the specs on the gun for required cfm from compressor.To small of a compressor and you will make a couple of passes on what your painting Then you will be waiting for compressor to build back up.It will get frustrating.
Tom
 
The gun you are describing is a gravity feed gun. Really the only benefit of a gun of that type is you can use every drop of paint. With other type sprayers you need an ounce or so of paint in the bottom of the cup for it to pick up. This means if you work with a high dollar catalyzed finish you don't have to throw away an ounce or so of paint just so the gun has something to pick up. A catalyzed finish can't be saved because once the hardener is added you have to use it or loose it. If though you are not working with a finish that has a shelf life of hours then it doesn't matter. Just keep filling the gun. Personally I prefer a siphon sprayer. I do keep a HF gravity feed sprayer for the occasion when I work with catalyzed finishes.
 
(quoted from post at 21:02:32 04/30/17) Start with about 40 psi and see how it goes.
So generally speaking for LPHV ... and if you are starting with 40psi, what is the minimum CFM and tank size you would need? Would 6 CFM and a 20 gal tank be enough? How much would adding a moisture filter reduce that capacity?
 
There are a lot of variables as already stated. Probably best if you get the specs from the paint gun you intend to use, then check to see if your compressor is up to the task.

I painted a whole truck with a 30gal direct drive compressor from Sears with a HVLP gun. Said if was 5.5hp but if you do the math, it was 110V and used a 15amp plug, it wasn't 5.5hp! It did the job but it ran pretty much the whole time. You do NOT want to be in a situation where the paint is mixed and you're waiting for the compressor to build up sufficient pressure to effectively atomize the paint. Or, worse than that, you're painting away and the pressure drops below the intended set point and the spray pattern goes from a fan to a narrow cone and you get a bunch of runs or just poor atomization.
Paint is too expensive (in my opinion) to risk any mishaps and do overs.

I've since got a 80gal 7.5hp compressor that I KNOW is up to the task. That takes at least that worry out of the equation.
 
One more point. Some guns will come with different size tips for spraying different material. Mine has a 1.8mm tip which is good for thicker things like primer and a 1.4mm tip which I use for base and clear coat. Some people use a separate gun just for each stage but for the DIYer that's not necessary. Just something else to consider when shopping for a gun.
 
thank you for all you combined inputs, ideas and suggestions. I will check out all the compressor info, the gun info and the paint info I can find. thank you again. Wm.
 

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Back
Top