However, it is not only the absolute silver -- or gold -- content of an alloy that is decisive for a flute’s tonal characteristics. There are several other factors which also play an important role: 1. The crystal structure The crystalline structure of a gold or silver alloy is formed by drawing the pipe, which results in considerable hardening of the metal. If the pipe is heated once again (anneals), re-crystallisation takes place. This simply means that the metal will again become permanently soft, and the original crystals will reshape. In earlier times this “annealing” of the pipe was one of the great secrets of a flute maker, since it was simply impossible to visualize the metal structure. Today, however, microscopic examinations and hardening tests allow exact determination of the thermal and mechanical processing of an alloy. 2. The alloy Pipe manufacturers generally only provide a general formula for the alloy, such as Ag 925 or Au 14ct. Additions in the per-thousand sphere, although they considerably influence the vibration characteristics of an alloy, are not given. (The addition of Germanium or Silicon to 24ct gold, for example, leads to a considerable increase of hardening). Through a modern analysis process, it is possible to exactly define the effects of such “additions” and, thus, to control tonal quality today. 3. New alloy 22ct gold proved to be especially good in our experiments. This alloy, which comprises only gold and silver, but without any copper additions, combines the positive tonal characteristics of gold and silver.