I have a fairly decent spray gun made by Greco that is giving a problem. As you see the horns of the cap are collecting lacquer and causing the gun to give me a inconsistent spray pattern. I use the 3M PPS and hang the gun upside down to prevent the lacquer from dripping out.

If it matters I spray a two part catalyzed lacquer that I have used for 10 years or more with no issues.

Any guesses as to what is causing the snotty build up?
A quick scrape with a sharp edge followed by soaking overnight in lacquer thinner clears it up but it comes back over time.

Many of those two part coatings can and will react with moisture or air. Even though you don't have it catalyzed it will still happen.

When I painted cars, when I was finished spraying, i’d remove the needle & aircap & they’d go into a clean cup of lacquer thinner. Next day, get ‘em out, blow them off, quick wipe down & re-assemble for the next job. Day in, day out.

Has that gun been dropped lately?

Too much catalyst, I have a Kremlin 10.14 I spray with and they had to back the amount of cat they mixed into it because it was starting to set up to fast Mine use to do the same thing. I would also check the tiny pin holes where the air bleeds thru to give you the pattern they could be clogged.

One of the hole ont the spray gun head is mildly clogged, make the spray pattern uneven and when you spray the paint was titled to that side .

quote:

Originally posted by recoatlift:
When I painted cars, when I was finished spraying, i’d remove the needle & aircap & they’d go into a clean cup of lacquer thinner. Next day, get ‘em out, blow them off, quick wipe down & re-assemble for the next job. Day in, day out.

Yeah, this.

I have a gun similar to yours and have found letting all parts soak over night works wonders.

I think your ratio might be a little off also,it does happen with Bink's and Develvius guns also.
It also happened when I work at Ford back in the sixties,We had a paint gun can and kept a spare spray gun in thinner for quick change when it happened for a fast switch out.
Seem to happen on days of lots of rain.
Our paint was fed thru lines thru the oil house and was heated,would actually burn your skin if you horsed around and sprayed you buddy

Whenever you are finished spraying for the day, always flush your gun with clean thinner and blow out your passages. Take your gun apart and soak it in Acetone for a day, then scrub, blow out your passages, use a cleaning needle to clean out your aircap, then reassemble.

I'm the guy who makes the post-catalyzed lacquer so I know. You can speak to me directly if you need any further assistance.

If I understand what you are describing, this is happening as you are spraying. You start out clean and before you are done it is snotty. This happened to me when I lent my gun out to a friend and he dropped it. One of the air horns was bent just enough that the other horn was blowing materials against it because the two air streams were not aligned anymore.