PPG HVLP Painting Question

[Tony Jacuzzi]

Painters :

I have been painting with an HVLP Sharpe detail gun with a 1.0 tip using PPG concepts for a while. I was just reading over the PPG DCC product catalog and they state that 10 psi at the gun is the right pressure for this paint product. The Sharpe gun manual says 29psi max. I have been painting at the 29 max, my results have been OK but I always need to polish as I always seem to end up with a "dry" spot. Should I be turning down the pressure at the gun, and what can I expect when I do.. Thanks Tony J

 

[Don Ferrette]

Hey Tony one of the very best things you can add to your gun is a good guage/regulator right at the gun's air inlet like the Sata guage/regulator. I went with the Sata unit not just because I now use the Sata MiniJet 4 but because it is real easy to read & very accurate. The Sata guage has color coded area that is easy to see a quick glance while spraying. All I do is just before paint is poured into the gun cup is check the guage to be sure the needle is in the middle of the green range (1.5 bar) while the trigger is held wide open, quick & simple. There probably are cheaper guage/regulators out there but for me the $55-$60 for the Sata piece is definitely worth it. Here's a link to one on Ebay- http://cgi.ebay.com/ebaymotors/SATA-PAINT-...sspagenameZWD1V

As for the "dry spot" well perhaps you might be releasing a touch too soon at the end of your spray pattern & leaving a spot not properly "wetted" with paint. I can't say for sure but I had a dry spot happen once when I ran the paint cup dry right at the end of a shoot. Hope this helps. B)

 

[dannyual767]

Painters :I have been painting with an HVLP Sharpe detail gun with a 1.0 tip using PPG concepts for a while. I was just reading over the PPG DCC product catalog and they state that 10 psi at the gun is the right pressure for this paint product. The Sharpe gun manual says 29psi max. I have been painting at the 29 max, my results have been OK but I always need to polish as I always seem to end up with a "dry" spot. Should I be turning down the pressure at the gun, and what can I expect when I do.. Thanks Tony J

Tony, I'm just an inexperienced painter trying to learn. Anyway, terms can be confusing and one of those is "10psi at the gun." I read that this is really an internal pressure at the tip that we users can't measure! This 10psi equates to something close to 29psi read on a guage/regulator assembly right at your gun's air inlet point.

I hope this helps some. Maybe someone else can elaborate on this.

 

[Topfuel666]

I use guages on all my guns. Sata and others recommend doing so to measure the pressure going into the gun accounting for pressure drops in the feed line. My setup indicates 23psi at the regulator and 10 psi at the gun. I use 1/2" hardlines to the moisture trap and then 5/16" hose to the gun.

Dry spots could be running out of paint or you pulled away / released at the end as Don said.

Bill

 

[Rusty]

Painters :I have been painting with an HVLP Sharpe detail gun with a 1.0 tip using PPG concepts for a while. I was just reading over the PPG DCC product catalog and they state that 10 psi at the gun is the right pressure for this paint product. The Sharpe gun manual says 29psi max. I have been painting at the 29 max, my results have been OK but I always need to polish as I always seem to end up with a "dry" spot. Should I be turning down the pressure at the gun, and what can I expect when I do.. Thanks Tony J

Tony, I'm just an inexperienced painter trying to learn. Anyway, terms can be confusing and one of those is "10psi at the gun." I read that this is really an internal pressure at the tip that we users can't measure! This 10psi equates to something close to 29psi read on a guage/regulator assembly right at your gun's air inlet point.

I hope this helps some. Maybe someone else can elaborate on this.

This is exactly right 29psi at the gun is suppose to equate to 10 psi at the cap....I set my regulator at appr. 50-60 psi then down to 29 psi at the gun.....if u use to much pressure at the gun u can actully blow out the center of your fan pattern and get a dry area in the center....the pattern will look kinda like a skinny figure 8.

 

[Don Ferrette]

This is exactly right 29psi at the gun is suppose to equate to 10 psi at the cap....

Well no it's not really "exactly right". With an HVLP detail gun 29psi at the gun inlet will be right on the line of too much (assuming no issues with gun). Most current HVLP paints shot in smaller quantities tend to spray best at 1.3-1.5 bar which typically is right around 21-22psi at the gun air inlet and 10-11psi at the cap. This is set with the trigger pulled wide open, do not try to set with the gun idle and for this I consider an accurate, easy to read guage/regulator at the gun air inlet to be well worth the cost (which is why I use the Sata piece). Too much pressure will more often result in runs and sags because the higher pressure is pushing the paint away from the center of the pattern. Now keep in mind the key word here is detail not a full sized, higher capacity gun. Personally the only time I've seen the middle of a pattern get "blown out" is the paint flow needle is in too far, the tip/cap size is too small or the cap is partially clogged but hey that's just me.

 

[Rusty]

This is exactly right 29psi at the gun is suppose to equate to 10 psi at the cap....

Well no it's not really "exactly right". With an HVLP detail gun 29psi at the gun inlet will be right on the line of too much (assuming no issues with gun). Most current HVLP paints shot in smaller quantities tend to spray best at 1.3-1.5 bar which typically is right around 21-22psi at the gun air inlet and 10-11psi at the cap. This is set with the trigger pulled wide open, do not try to set with the gun idle and for this I consider an accurate, easy to read guage/regulator at the gun air inlet to be well worth the cost (which is why I use the Sata piece). Too much pressure will more often result in runs and sags because the higher pressure is pushing the paint away from the center of the pattern. Now keep in mind the key word here is detail not a full sized, higher capacity gun. Personally the only time I've seen the middle of a pattern get "blown out" is the paint flow needle is in too far, the tip/cap size is too small or the cap is partially clogged but hey that's just me.

ON my detail guns I run them at the same pressure as my full size HVLP guns and airbrushes get more pressure than full size guns....but u definitely need to set the pressure with the trigger pulled. Most painters I know run guns with the paint flow adjustment all the way open and regulate the paint flow with the trigger. All guns or paint don't spray the same and u will be amazed sometimes at what a good cleaning will do with the way your gun sprays. The only real time I have had problems with runs and sags MY ARM AND EYES WERE OUT OF ADJUSTMENT! LOL

 

[Don Ferrette]

The only real time I have had problems with runs and sags MY ARM AND EYES WERE OUT OF ADJUSTMENT! LOL

Now THAT'S funny Rusty! :lol:

You are right about proper gun cleaning, the number one killer of spray guns & SUPER critical on HVLP stuff. One thing I found interesting is that alot of the "high end" spray gun suppliers are now recommending using acetone to clean the HVLP guns out. Supposedly it's more effective at cutting loose the residuals. I have been using laquer thinner for years but may give this a go next time I shoot some paint. B)

 

[Rusty]

The only real time I have had problems with runs and sags MY ARM AND EYES WERE OUT OF ADJUSTMENT! LOL

Now THAT'S funny Rusty! :lol:

You are right about proper gun cleaning, the number one killer of spray guns & SUPER critical on HVLP stuff. One thing I found interesting is that alot of the "high end" spray gun suppliers are now recommending using acetone to clean the HVLP guns out. Supposedly it's more effective at cutting loose the residuals. I have been using laquer thinner for years but may give this a go next time I shoot some paint. B)

I have always used laquer thinner too...I may try acetone depending on how the price compares....high and higher I am sure. Some the tiny holes in the air cap can be a pain to keep clean and a bigger pain when they plug up.