Classic cars forum & vehicle restoration.

Old-Nail · Joined: 23 Nov 2007 Posts: 853

Does anyone know what PSI the average spray can emits the paint at?

SloResto · Joined: 17 Feb 2008 Posts: 36

Good question and I have no idea. My guess would be somewhere between 25 psi and 40 psi mimicking a low pressure spray nozzle with enough pressure to atomise and propel acrylic lacquers and enamels.

For an accurate answer you would need to ask the spray can manufacturers.

Good luck.

ukdave2002 · Joined: 23 Nov 2007 Posts: 4124 Location: South Cheshire

Most paint shops will make up cans of paint these days (Halfords do it) I guess they might know.

Old-Nail · Joined: 23 Nov 2007 Posts: 853

Hmmm... it was just a thought.

I've been reading about these HVLP spray set ups and fancied trying one out, that lead me to wonder what exactly that 'low' pressure was.

Finally I don't know what your local Halfords is like but I find it difficult to believe the staff at my one would know the difference between new year and New York... they have completely mastered the art of indifference by their 17th birthday!

Uncle Joe · Guest

For a while now, I've been looking at HVLP guns myself. Typically, the good ones seem to work at about 30psi, but use maybe 16cfm to do it. dont know if this helps with your question, but I doubt that an aerosol can pass that amount of air.

magic9r · Joined: 13 Dec 2008 Posts: 33

The point abouth HVLP is the High Volume bit, they still use shedloads of air, the dynamics of the airstream result in a higher percentage of paint deposition.
How is an aerosol relevant to this?
Regards,
Nick

Jim Walker · Posted: Sun Dec 14, 2008 2:48 pm Post subject:

I have used a Volumair set up for years, which as its name implies is high volume low pressure. I have a conventional spray gun, but only use it for touching in. Unfortunately the Volumair seems not to have been produced for many years or I would heartily recommend it. Mine is at least 30 years old and still works perfectly.

The advantages are that it produces less airborn overspray, better cover without sags because the paint leaves the nozzle slightly warmed rather than cooled as with pressure spraying, more economical paint usage and greater ease of movement because only a power lead is trailing behind you. Having said that my 'blower is carried on a shoulder strap, but I believe some HVLP systems stand on the floor.

My sprayer has repainted almost everything from funeral limousines to wheelbarrows. It was claimed it could also handle almost anything from creosote to emulsion paint with a change of needle and jet, though I have never tried anything other than cellulose, enamel and two pack paints.
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clascar · Joined: 27 Oct 2008 Posts: 83 Location: mid cheshire

I use HVLP guns with my conventional compressor. I like the smaller ones the best,
. They are not as air hungry and I get good results with minimum overspray. I also have an apollo HVLP stand alone system which is good for bigger jobs. The apollo also heats the air slightly which can be a help in cooler conditions.
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Greeney in France · Posted: Wed Dec 24, 2008 10:32 pm Post subject:

I have a gravity fed HVLP but dont seem to get on with it, it never seems correctly set up, what is the best compressor pressure?
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Jim.Walker · Joined: 27 Dec 2008 Posts: 1229 Location: Chesterfield

Greeney, I have been trying to log on to (hopefully) answer your question about the best compressor air pressure. However, I changed my computer and have been unable to log on for about three weeks. I must say that Rick has been extremely patient and helpful in trying to help me overcome the problem. My user name has changed slightly and I have yet to set up my avatar etc. if it does not come up with this post.

I don't think you are likely to have any degree of success employing a compressor, unless some kind of expansion tank in the air line would answer, or perhaps a very small HVLP gun as mentioned earlier.

All the HVLP guns I have come across employ a BLOWER, not a compressor, with an output of high volume (rather like a hair dryer) fed to the gun through a pipe with an internal diameter of about 18mm so as to not restrict flow. There is so little pressure the output can quite easily be stalled by a hand over the end of the pipe. The blower internal action on the air also warms the air up slightly and the recommendation on mine is to wait for the output to warm up before commencing use.

Greeney in France · Posted: Fri Jan 02, 2009 8:41 am Post subject:

Thank you Jim, I will take a photo of it. The gun looks the same as a normal gravity gun fed by air in the normal way but has HVLP written down the side Embarassed

I much prefer my Sealy gold even over my DeVilbiss I think its what you get used to
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clascar · Joined: 27 Oct 2008 Posts: 83 Location: mid cheshire

I wouldn't go back to a conventional gun again. The big advantage of HVLP is the reduction in overspray and dust. They are also more economic on paint. HVLP guns do come for use with ordinary compressors, and look like an ordinary gun. Just to add to the confusion there are LVLP guns as well. from what I can find out these gun needs to be scrupiously clean to get consistent results. I can't gauantee this so I haven't bothered.
_________________
When I exhibit a car I get the Shudders. People queue up to tell me.
You should have done that, you should have done this. Ray