Last week i had an outside performance/competition and as im playing i notice my bell "smoking". This isnt the first time i have noticed it (indoor performances too), it was jus constant though last week, any thoughts on what it could be or why ?

that is what i thought until i remembered doing it at U of M

how often do you clean your horn? it may be dust or build up inside your horn and when you play the amount of viberation in your how could cause some of the build up in your horn to let loose and it fly out your horn since air is being put through the horn. But if you havn't cleaned it, get a snake and warm water and clean it.

i heard warm water strips the laquer

hot water does, not luke warm water though. normally the tempature of the water is just a little more hot then the room temptature (based on around 72F) so only really hot water will. but also, on the outer slide, don't leave it to soak because of the water key (spit valve), the cork in it will act like a woodwind cork and the aheasive will dissolve and the cork will come off and then it won't work unless you put a new one in or something else...so yah, not hot and don't let it soak, run a trombone snake through it to get all the build up out, and do that about once a month and hopefully you'll not have that happen again.

If you're a strong player, you can actually see your breath in a room at... room temperature. But generally, you won't see it out of the bell unless you are at marching band practice on a thursday night at 9:30 in November getting ready for SCSBOA championships blowing your brains out...

Oh and on a "horns down" after playing you can usually see your mouthpiece 'smoke' for a minute or two.