Paint Gun Issue

S

Savvy

Member
I have a DeVilbiss Startline Blue with 1.8 tip.
I'm spraying PPG K36 Primer 5:1 on a clean sandblasted spare tire cover.
The pressure coming out of the compressor is 85lbs.
The pressure regulator at the base of the gun is set to 35lbs.
The paint hits the metal and sets up like grains of 90 micron aluminum oxide.
Adjusting the pressure doesn't help.
I used the gun last spring at a different location spraying the same paint...no problems.
The air is dry and clean.
I took the gun apart and soaked it in lacquer thinner for two days, then cleaned it all up.
Remixed new paint.....same result.
Any input / suggestion would be appreciated.

Cheers!
 
Check and see what reducer you are using. It may be fast drying, and if it is that is your problem. If it is slow drying reducer, then you need to add more reducer to your paint. Marv
 
A lot of these products have a pot life of 45 minutes, thats at 70 degrees, start knocking off time for temp increase. There are a few high build primers out there that will just drive a guy nuts, look for something with a more forgiving pot life if you can't resolve the problem.
 
It sound like what Marv said ...maybe too fast of reducer. What is the temp where you are painting? And also is the metal you are shooting in the sun and heating up by chance? A few factors to look at......
Ron in AZ
 
I'm no paint expert by any means but someone on Fordbarn recommended warming the paint on a food warmer....claimed that it worked wonders....others agreed.
 
Joe/Ct said:
I'm no paint expert by any means but someone on Fordbarn recommended warming the paint on a food warmer....claimed that it worked wonders....others agreed.
Click to expand...

Used to do that years ago with enamel paints (had a special coffee urn style electric pot with a spigot on the bottom to dispence the heated paint) This eliminated any use of thinner. Never heard of this process being used for lacquer or two part catylized urethanes.
 
I'm not familiar with your spray gun at all, but one of the situations that I've seen over the years is the nozzle being plugged. Un-screw the nozzle and soak in in some lacquer thinner for about 10 minutes and try again. Another thing that you might try is just running lacquer thinner through the gun to clean it. It sounds like you are getting too much air and not enough material through the gun.
 
I have had this exact same issue with Dupont Fill and Sand primer. Adding more reducer took care of the problem.

-Lyndon
 
You stated that your mix ratio is 5:1, that would be for primer and activator,but you made no mention of using any reducer. If you add 1 part reducer (5:1:1) you won't have any problems.
 
I don't know that model of gun. I know you said you took it apart but depending on how far apart you took it if there are any of the packings around the fluid or air needles you should never leave it soaking in thinner. I have been using my JGA and MBC DeVibiss Guns for about 45 years in my collision repair shop and have never had to rebuild either gun, never left them soaking in thinner either.
 
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