Shimming is used primarily on flutes, sometimes on saxophones and more rarely on some clarinets. Using this technique, thin pieces of paper or plastic are put under the pad to level it. This requires a great deal of experience and patience. The padding of a professional flute with this technique takes about 5 to 7 times longer than the padding of a clarinet. If done properly however, the results can be superb.
As with the floating technique, a perfect mechanism is required to get a good result. The pad is first put into the pad cup, after which thin washers are inserted under the pad to level it parallel when it touches the tone hole. The handling of the soft pads requires expertise as the shimming process can compress the pad, sometimes requiring a recovery period of 1 to 2 days without playing to allow the pad to recover to its original shape.
The development of the
represents a big improvement to this technique by replacing the traditional cardboard base of the pad with a stable plastic base. This high-quality pad costs more but is worth the extra expense.