The Ford Barn

Bruce_MO · 09-12-2015, 04:42 PM

I have an old DeVilbiss siphon spray gun and I recently added a regulator and gauge at the gun... previously guessed at air pressure at the gun using a chart I had for regulator-to-gun pressure drop for length and diameter of my hose.

Now that I'm using it, I'm confused...

1) When a type of paint specifies a pressure "at the gun", do they mean before or after you pull the trigger? I'm supposing it's the pressure that's atomizing the paint, i.e., after you pull the trigger. But I'm pretty much a amateur at this and don't do that much painting.

2) What's a good "at the gun" pressure to use for single-stage acrylic enamel?

Thanks in advance for your insights.

mcorrell · 09-12-2015, 05:00 PM

I used to do a lot of painting with enamel. I adjusted the pressure while spraying the gun. I usually used about 50 -60 psi with a quality suction type gun. You will also have to learn how to adjust the pattern for best coverage for a given surface. For instance, on sheet metal or large flat surfaces I like a 8 in or so wide pattern. For chassis or where to have multiple small surfaces like a tube frame i like a 3 in wide pattern.

Fred K-OR · 09-12-2015, 06:22 PM

I set my compressor pressure at about 40 to 50 lbs. May vary depended on what I was doing.

Osage Orange · 09-14-2015, 08:25 PM

I set pressure at the gun at 45, IIRC, and that was DuPont acrylic enamel and the proper recommended reducer for temp and humidity. Build primer went higher, with the fan wider at 8 to 10 inches but staying close to your work.

chap52 · 09-15-2015, 01:42 PM

Go on "youtube", lots of painting and spray gun set up videos there. Getting ready to paint my truck when the Arizona weather cools down a bit so I have been "schooling" myself on you tube.
Check out tpcglobal.com for paint kits.

ian Simpson · 09-16-2015, 09:00 PM

Sponsored Links (Register now to hide all advertisements)

As a hopeless, self taught amateur, I set the pressure at the tank, and then spray hundreds of dollars worth of paint on a piece of scrap sheet metal, changing the pressure until I am satisfied with the result.

Watched seasoned professionals do the same thing to accommodate different atmospheric conditions.

Main difference? They did it in one or two test shots, not my twenty-one or two.

09-12-2015, 04:42 PM	#1
Bruce_MO Senior Member Join Date: May 2010 Posts: 433	Enamel painting questions I have an old DeVilbiss siphon spray gun and I recently added a regulator and gauge at the gun... previously guessed at air pressure at the gun using a chart I had for regulator-to-gun pressure drop for length and diameter of my hose. Now that I'm using it, I'm confused... 1) When a type of paint specifies a pressure "at the gun", do they mean before or after you pull the trigger? I'm supposing it's the pressure that's atomizing the paint, i.e., after you pull the trigger. But I'm pretty much a amateur at this and don't do that much painting. 2) What's a good "at the gun" pressure to use for single-stage acrylic enamel? Thanks in advance for your insights.

09-12-2015, 05:00 PM	#2
mcorrell Senior Member Join Date: Aug 2014 Location: Canotn, NC Posts: 163	Re: Enamel painting questions I used to do a lot of painting with enamel. I adjusted the pressure while spraying the gun. I usually used about 50 -60 psi with a quality suction type gun. You will also have to learn how to adjust the pattern for best coverage for a given surface. For instance, on sheet metal or large flat surfaces I like a 8 in or so wide pattern. For chassis or where to have multiple small surfaces like a tube frame i like a 3 in wide pattern. __________________ 1929 (early) Model A Special Coupe - restored to original 1964 Buick Wildcat convertible

09-12-2015, 06:22 PM	#3
Fred K-OR Senior Member Join Date: May 2010 Location: Stayton, Oregon Posts: 3,806	Re: Enamel painting questions I set my compressor pressure at about 40 to 50 lbs. May vary depended on what I was doing. __________________ Fred Kroon 1929 Std Coupe 1929 Huckster

09-14-2015, 08:25 PM	#4
Osage Orange Member Join Date: Sep 2011 Location: Powell Siding (near Cleveland), MO Posts: 82	Re: Enamel painting questions I set pressure at the gun at 45, IIRC, and that was DuPont acrylic enamel and the proper recommended reducer for temp and humidity. Build primer went higher, with the fan wider at 8 to 10 inches but staying close to your work.

09-15-2015, 01:42 PM	#5
chap52 Senior Member Join Date: Jun 2013 Location: Marana Arizona Posts: 1,776	Re: Enamel painting questions Go on "youtube", lots of painting and spray gun set up videos there. Getting ready to paint my truck when the Arizona weather cools down a bit so I have been "schooling" myself on you tube. Check out tpcglobal.com for paint kits.

09-16-2015, 09:00 PM	#6
ian Simpson Senior Member Join Date: Apr 2014 Posts: 709	Re: Enamel painting questions Sponsored Links (Register now to hide all advertisements) As a hopeless, self taught amateur, I set the pressure at the tank, and then spray hundreds of dollars worth of paint on a piece of scrap sheet metal, changing the pressure until I am satisfied with the result. Watched seasoned professionals do the same thing to accommodate different atmospheric conditions. Main difference? They did it in one or two test shots, not my twenty-one or two.