This is best experienced in lessons, of course, but here is a basic walk-through of the concept.
1. Play a pedal B-flat. This is usually a great note on the trombone! Just take a huge breath and blow, letting the lips basically flap in the breeze. Note the air usage - or what I sometimes call 'blow profile' - it should be full & free.
2. Play a high b-flat (did you take the same great breath for that as for the pedal? I hope so!) Compared to the pedal, I would describe the blow profile here as focused & faster. I really like to keep the concept of "free" here as well. "Fearless" is another good concept in the upper register!
So, using the extremes, we have described the difference in air flow and focus between high and low notes. This basic relationship exists also when the notes are closer together.
3. Play back and forth between low B-flat and F on the bass clef staff, and notice that the basic blow relationship is as above - albeit on a smaller scale, due to the closer proximity of the notes. This is the practical application of air flow & focus. I consider it the key to flexibility studies brass instruments - and is the reason I prefer term "Blow Patterns" or "Flexibility Patterns"over "Lip Slurs". We play a wind instrument, after all - not a lip insturment!
So we have flow, focus, full, free, faster, focused, free, and fearless. Going further with 'F-words' - how about "Flop and Flip"? Again - this is best demonstrated in lessons, but here goes:
1. Play a few downward slurs from F to B-flat on the bass clef staff. By our description above, these downward slurs go from a faster more focused blow to a fuller, rounder one. Make sure you have a forward, pro-active blow worthy of a wind instrument. When done this way, the downward slurs have a feeling similar to flopping down into a big stuffed chair. Let's call this a 'flop'.
2. Now do a few upward slurs from the same F up to the middle b-flat. The blow profile hereis from a full and round to a more focused and faster air stream - all relative to the register, of course. Again, make sure it is a pro-active, forward streaming blow. Now - not being able to imagine flopping upwards, how about the picture of a 'flip'? Not unlike flipping a Frisbee or something. Click here for an exercise crafted to underscore this concept.
Anyway - with such descriptive license, the idea of flipping and flopping does add to the blow profile picture. I use all of these conceptswhen doing my flexibility studies. Try it - and remember: it is a wind instrument, not a lip instrument!
Full, free, faster, focused, free, fearless, flop, flip. Any more?