Of course, mouthpieces wear off, slowly but surely. The specific manner a mouthpiece is battered by the reed makes it wear away in places and in this way the behaviour of the reed shows itself. Here we interest ourselves in the particular way in which this happens.
Now what does this wear look like under a magnifying glass? It is to be seen most easily in silver plated mouthpieces: the brass shows through, but ebonite mouthpieces show similar marks although in a slightly different way. Ebonite mouthpieces namely show a high gloss on the spots of wear and get dirty with a calcified sediment in the non-battered spots.
We find wear along the inside of the rails up to a length of about 3½ centimeter from the tip (for alto). Marks of wear can often be traced down to the rear end of the window. Yet, in the first half up to three quarters of a centimeter no sign of wear is to be found. The tip rail only shows a very fine line-like stain on its inside, where it meets the baffle, but not right into its corners. It all looks more or less like the red colouring in the drawing below. Study reveals that no wear is to be found on the rear end of the window.
- The reed is supported on the inside of the rails: the flat side of the reed therefore must bulge a little and that indeed is the case. This deforming of the reed will have different causes that work together at the same time: the underpressure in the chamber during half the cylcle of the reed vibration, the lip pressure of the embouchure which rests mainly on the centre of the arched vamp of the reed and finally (and probably the most important reason) moisture, which makes the reed swell on the inside.
- Marks of wear are at least a centimeter longer than the length of the lay. This can only be explained when we assume the reed to vibrate over a much greater length than the length of the facing alone(!). You would almost suspect the overpressure in the mouthpiece chamber during the other half of the cycle to push the reed away from the mouthpiece.
- Underpressure in the mouthpiece chamber makes that the tip is loaded on its innermost rim alone.
- Use a ligature that provide for a minimum of damping in order not to hamper vibrations that obviously are there.
- A broad tip rail as it were takes away the foremost rim of the reed tip; after all, the tip rail is loaded along its inside. In order to maximize the sensitivity of the reed tip, the tip rail really could be very fine. Accuracy of form is a prerequisite, though. Such mouthpiece tips would be extremely prone to injury, too.
But it also follows that mouthpieces vary in sound according to the broadness of their tip rails, or to put it differently, that the width of the tip rail is another defining factor in sound production.