I know better.  Big time, I know better.  Never hurry a cleanup in a gun, I tell everyone.  yeah, right.
Yesterday I had to leave in 15 minutes, and decided to put the last coat of two-part clear on a guitar I have about finished.  Mixed the clear, cranked up the compressor, and shot the beast.  Disaster!!!
I had the same thing the day before and shot a coat in a hurry, then poured some thinner into the gun and sprayed it out, making my departure on time and a bit smug that I got the clear on okay.
Yesterday's disaster was in the form of the beast spitting cotton onto the back of the instrument in big globs, giving me a near heart attack.
There's no real harm done except for the extra twenty-seven days of sanding ahead of me.  (Well, maybe I stretch that a bit.)
I disassembled the gun and found clear in fine sheets around the needle, little specs in the mixing chamber, and cotton balls in a couple of other spots.  I know just spraying thinner through the gun, especially with two-part, doesn't sufficiently clean it, but allowed myself to rush my job.
Fortunately for me, this is on hardwood, (maple) and not a balsa plane.  I can't imagine the grief it would cause on a ship!!!
Lesson here, guys CLEAN THAT GUN RIGHT, don't be a doofus like me!

Good advice, good advice.

You're welcome, Coach.  maybe Mark S. or Randy P. will jump in here with advice on better solvent to use for cleaning than the lacquer thinner I use.  Or . . . I could just ask my guy where I buy my supplies?  Oh heck, Mark and Randy are more fun to talk to.

Hey Will,, as you know,, cleaning the gun is part of the spraying process,, DOH!,, LOL

the real tragedy is when you get urethane cured in a gun and ruining the gun,, I sprayed a car one time,, spot repair,, and as I was putting on the last coat of clear, a customer came in needing an estimate,, It was in the 90s that day, it was about 4 pm,, and they customer had a cool car, and loved to talk. By the time I got his estimate done, It was time to go home,, guess what,, sigh,,

When I clean my guns, I use laquer thinner to flush the gun,, I use a flux brush to scrub it inside and out, I take off the air cap, fluid tip, and needle,, then I flush scrub it with more thinner,, I reassemble the gun, then flush it with Urethane reducer using air pressuer just like I was spraying..

Other than that, What Dandy Randy says,, of course he did fail to mention his special technique using small mammals (bats) to help clean his equipment,, muah ha ha

Excuse me, they are micro-gremlins. The bats are unwelcome guests.