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PSI while spraying

#1
Is the only downside to higher PSI while spraying (general question, epoxy/base/clear) that you will have excessive overspray?

I have been spraying epoxy at varying pressures, and I'm amazed at how smooth I can get it over a 80-220 grit surface. After a couple coats it's close to glass. Today I had some epoxy that had been mixed overnight, and it was spraying like it had thickened up a little too much, so I upped my pressure to 30 and it turned out incredibly smooth.

So now I wonder, is the only downside excessive overspray?
 
#2
Too high of a pressure will split your fan and make excessive overspray and dry spots. But, a little higher will atomize better. 30 isn't really that high.
 
#3
It depends on the gun, 30 is way to high for some guns and not enough for others.
My guns vary from 18 to 40 psi.
You need to start at what the mfg. recommends, most are better at a little more,
like 3 to 5 psi more.
 
#4
Call me crazy if you like but I believe the spray gun makes a certain sound when its at the right PSI.
Listen to the sound while holding the trigger full open and raise the PSI until it just starts to change pitch and sound more like a "hissing" sound.
Then look at your PSI. From there you can adjust up or down to get the pattern looking right. Like JC said it will vary by the gun.
 
#5
Call me crazy if you like but I believe the spray gun makes a certain sound when its at the right PSI.
Listen to the sound while holding the trigger full open and raise the PSI until it just starts to change pitch and sound more like a "hissing" sound.
Then look at your PSI. From there you can adjust up or down to get the pattern looking right. Like JC said it will vary by the gun.
There is a video by Collision Hub that has a SATA rep talking about the sweet spot of the gun. If you hold your hand in front of the gun (empty cup of course), pull the trigger then move the gun towards your hand, you will hear the tone change. That's the spot. Any closer, and it sounds violent.
 
#6
There is a video by Collision Hub that has a SATA rep talking about the sweet spot of the gun. If you hold your hand in front of the gun (empty cup of course), pull the trigger then move the gun towards your hand, you will hear the tone change. That's the spot. Any closer, and it sounds violent.
I’ve tried in the past to look up that video and I always come up short. I hear that very distinctive sound that you guys describe, specially with the SATA 5000, not so much with other guns.
 
#9
Surprised to see the fast travel speed of the gun, but 80%+ overlap to make up for it. Opposite of what I do.:oops:
Yes, me too. I shoot a 50% overlap because it was drilled into my head long ago. My travel speed is about 1/2 or less of what he was doing depending on which gun and what I am spraying.
 
#11
Call me crazy if you like but I believe the spray gun makes a certain sound when its at the right PSI.

i havent pulled the trigger on my guns for much more than woodworking projects in a couple years, but when i was having quite a bit of work in my shop and spraying auto finishes quite a bit , i was pulling the trigger quite often. i came accustomed to that sound youre talking about.
 
#15
I do this test most every time I spray, but a tiny bit more time pulling the trigger can make it look to heavy or too light. Seems like there is a 10 psi swing where I can make it look the same on a piece of paper.
When I set the pattern on paper I pull the trigger full open for 1 second (I say 1/1000) and then let go. Depending on the speed I am travelling when spraying I may back the fluid knob out a little more but most of the time it isn't necessary.
 

EddieF

Top Banana
#16
Too much & not enough airflow patterns in pic are the most help i'll say.
Easy to understand how horns blow the paint when too much or little psi.
 
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