A mouthpiece can require some special attention sometimes. Refacing especially can be worthwhile.
Refacings are changes to or reparations of the lay. Within margins it is possible to repair damaged or worn out facings. Especially with old much loved mouthpieces this is a chance to take. But also with new mouthpieces, that for some reason or other appear not to work correctly, the fault often lies with the facing.
What can you expect in such a case? You can expect a facing to be made crisp and clean again and that both rails are made to balance once more; the tip is made accurate again and the table is flattened if need be.
Besides you can look for a change of facing. Changes in facing have a major effect in response and sonority. In this way you can also adapt a mouthpiece to a certain type of reed or to an embuchure habit. Refacings do not only deal with (larger) openings but also with:
– making the facing longer (for a better response in the lower range)
– a change in the width of the tip rail (what can make a mouthpiece sound brighter or darker in sound)
– a change in the type of curve (to make the mouthpiece correspond better with embouchure habits or a reed)
What can you expect? You can expect the existing facing to be diagnosed prior to any work is done and a good deal of consultation. You can expect the facing to be made according to what has been agreed upon. Yet, you cannot expect magic. It is possible to make a lay according to specifications; it is impossibile for me to make you sound one way or the other. Any mouthpiece will do only so much for you.
Both ebonite and metal mouthpieces can be done, although some treatments are easier in the one case than in the other. In practice, only material can be removed. Adding material is possible in cases of restoration of antique wooden mouthpieces. Metal mouthpieces can be replated (either in silver or in gold), but manually the layer will never quite reach the original thickness and so will wear away again slightly faster.