The Stovebolt Site Forums The Shop Area Paint and Body Shop paint gun problems?

Hi All,

I have been painting my bar grill frame and hood latch sheet metal. I have been using the TCP Global single stage acrylic urathane paint,4:1 mix but you can add reducer if you like. I am using a devilbiss FLG3 finish line gun, hvlp. I used a 1.8 tip for the primer and 1.5 tip for the paint. I also tried the 1.3 tip for the paint. What I see is happening is that the paint is not atomizing correctly. It seems to go on real dry and without a lot of material despite adjusting fan and needle all the way out. This was with the 1.3 tip, it did not put out enough paint although I had everything backed out. Did not have a nice fan patter either.
When I switched to the 1.5 tip, it still did not atomize correctly and was more sporadic with heaving droplets and did not cover well, I had to go over the area several times for it to cover because it was too dispersed. It is difficult to describe what was happening but I have not been able to get good results with my set up???
I used medium reducer, the temp was 80 degrees. Any ideas what is going on, this novice painter is confused ?
thanks,
skipper

As you are pointing out, it's not an adjustment problem, so something else.

What is the humidity? Check for loose fittings on gun. Play with the air pressure. Clean gun again and look at a manual when assembling.

I am in the california bay area so the humidity is low. I do seem to have to fiddle with the air pressure. It is difficult to find a happy medium. I have a gauge on the gun but it did not seem to work at the recommended 25 psi? I had to run a bit higher about 33 psi. Yes, perhaps I need to take it all a part and soak . I been using laquer thinner, is that OK?

Should I alway use reducer even if optional? Perhaps my paint was too thick and needed more reducer. I added 10 percent to the paint.

make sure the paint pot is pressurized. I am not familiar with your particular gun but, on mine, every now and then the air supply into the pot (very low pressure) gets plugged so the pot actually has vacuum and no pressure.

Also, it almost sounds like your paint may not be stirred up enough, or is a bit too thick still.

Can you elaborate on how you are adjusting the air pressure? Do you have a regulator at the gun, and are your readings taken while trigger is half pulled (air only)? What are you using for an air supply (size of compressor)?

As Bartamos said, Is it possible that the gun may not be completely clean inside?

How long are you waiting for the paint to induce after mixing/ before shooting?

What is your distance from nozzle to panel? Sounds like you might be too far away. Post a pic of your spray pattern on test paper- that might help us!

My gun did similar things after I first used it, where it sprayed nicely. I learned the hard way about gun cleaning... Don't do a half arsed job after your done. COMPLETELY disassemble and clean the entire gun in, out, top, bottom to ensure that it runs flawlessly next time. Epoxy is hard to remove from the inside of a gun let me tell you.

I'm betting a dirty gun, especially if you lent it out to somebody. I will never do that again.

To adjust the pressure I squeeze the trigger half way and then adjust the pressure.
My compressor is a 60 gallon Quincy, it is a pretty good one.
I waited about 10 minutes after mixing to paint.
I had to get close, about 4 inches in order to get enough paint coverage.

I could be that the gun is dirty. I do clean it after every time I use it. I have been using laquer thinner, should I use something else?

I am far from a pro, painted 6 vehicles so far as a hobby. My latest gun is a Devilbiss FLG4. I clean mine with cheap lacquer thinner.
4 inches is way too close, should be getting good coverage much farther away.
I've never used that same paint but every paint I've used required thinning.
Is the vent hole in the cup clear?
Make sure the gun is clean, soak the nozzle in lacquer thinner, pull out the needle and make sure there is no paint buildup on it.
Sounds to me like the paint is too thick or the air pressure is too low.

I agree with the paint is too thick. I always use thinner when spraying single stage paint.Also like said above make sure to take the gun apart each time and soak all the little parts in thinner. I use laquer thinner