But having to play notes beyond my technical level has been the case since I started the band, as I've been the only horn the for four years I've been in it, with the exception of a few months a while back when a high school player joined us for a semester.
So I've been trying to figure out why the lip callus problem has popped up now, all of a sudden. It may well be that it's connected to my having to take allergy medication regularly for the first time in years, which dries mucus membranes, and my mouth, and so my lips. Philip Farkas talks about people using the "dry lip" method of playing having way more lip trouble.
UPDATE 12/1/08 - This entry got a hit from a Google search, so I thought an update would be in order. I think the dry lips from the allergy med was the part of the problem. Another was that the mouthpiece I was using was old and had lost its slippery sheen, so I bought a new one. Another factor was that I'd been practicing an average of two hours over the course of the day, and really working on the high register. Stopping the allergy med, the new mouthpiece and dialing back practice time all seem to have helped. Also, I've tried to be better about applying "A&D" ointment, an over the counter product that's basically like Chap Stick but with vitamins A and D added, after playing and overnight. The callus is smaller, thinner and seems to be disappearing.
Maestro and cousin Steve, both brass specialists, suggested using a different mouthpiece with a broader rim and smaller cup. I've used a Farkas Very Deep Cup from the very beginning because the tone is so much more appealing. Other mouthpieces I've tried produce, for me, a sound not worth pursuing. In fact, looking into it all, discovered there's a Farkas Extremely Deep Cup, and if the callus completely goes away, might try one of those.
UPDATE 12/7/08 Trying to decide whether or not to try using a little vinegar to clear any lingering lime deposits in the horn, Googled around and found this great write-up on horn maintenance, the best I've come across. This passage really jumped out:
NOTE: Never play a mouthpiece with plating worn off on the rim or inside the cup. Get it replated or replaced to avoid the possibility of lip infection.
I think what precipitated my problem was that the outermost layer of the dry lip couldn't slide on the old mouthpiece and got partially separated from the layer next down, sort of like a blister. Then that thickened into a callus.