I'm glad to have sparked some interest in the master himself, Mr. Mendez. Several folks have e-mailed me off-TPIN for more info, so I'll do my best to recall other details of the clinic.
As I've already stated, he was very personable and approachable, and patiently answered every question, often throwing in some playing demonstations to illustrate his point. Specific items I can recall:
1. Pressure - "Use as little pressure as necessary. You don't need pressure. Watch." With that, he held the third valve button of his Olds Mendez trumpet between the thumb and forefinger of his right hand, very gently, and brought the mouthpiece to his lips. He then played, in eighth notes, low C, second line G, middle C, E, G above the staff, and high C, and back down again, clean and clear as a bell. "Anybody want to try?" he asked, but we all just laughed.
He did let each of us try his horn. I'd never seen a trigger before, much less two, so I asked about those. His mouthpiece had a very small diameter cup and a tiny hole. I later came to learn it was close to a copy of a Bach 10 1/2C, with a slightly wider, flatter rim. It also had a lot of mass to it, not unlike the mega mouthpieces we see so much today, so he may have been ahead of his time in the design category.
2. Playing high - Range wasn't what Mendez was all about, but he had a decent range, and certainly an impressive range to us Jr. High School and High School kids. In the concert, he played a few high F's and one High F sharp (or so he said ... in retrospect, listening to his recordings, those are the notes therein). In any case, he was very patient in answering, "Before you can play high, you must play low." He suggested a lot of lip slurs to improve one's range. Didn't have much more to say. The inference was to perfect what you could comfortably play now, that the rest would come.
3. Playing Fast - Some of the guys thought he must have some gimmick or trick to play the way he did. Obviously, no trick was involved. "Practice, practice, practice," he said. "There are no shortcuts. If you want to play fast, first you must learn to play slow."
He demonstrated double and triple tonguing, and confessed it had taken a LONG time for him to learn them. He said his nickname as a child in his hometown in Mexico was "Mr. Tu-Ku-Tu," because everywhere he went, he was always verbally practicing the multiple tonguing syllables.
4. Playing with power - "To play loud, first you have to play soft." He told us about being on the road and still needing to practice, so he'd practice pianissimo in his hotel room, so as not to disturb the other guests. Then he played some very soft, intricate passages that were barely audible, to demonstrate. Amazing.
5. Breath control - He was BIG on breath control, and talked about the need to constantly improve one's lung capacity. He said he used to swim underwater a lot to do this, but that just a brisk walk every day would also do the trick. He had another suggestion, which involved playing as long as you could in one breath, then trying again, adding one more measure. Then again, with one more measure, etc.
6. He also told us people like to see music being played, as well as hear music being plated. He admonished us against playing with our instruments pointed down all the time, like clarinet players. From that day on, it was "bells up" for all of us. If you ever see a clip of him playing, its hard not to be astonished at his showmanship. He was VERY, VERY mobile, pointing the horn all over the place, first at the front row, then the back left of the auditorium, then the front right, for example. On the high notes, he pointed the horn practically straight up. Man, coupled with his sound and technique, it was one exciting experience!
7. Finally, the thing he said that stayed with me the most was to "Make every note a solo." Every single one. If you do that, the piece plays itself.
That's about all I can recall. It was a long time ago, but obviously made quite an impression on me. In retrospect, it was one of the formative experiences of my life.