Posted by Chuck on October 30, 2000 at 12:18:50:
In Reply to: tuba with all the fixins' posted by Ryoko on October 29, 2000 at 19:43:57:
Scratches are repaired by buffing with a slightly abrasive compound (usually jeweler's rougue). Note that this does remove material. In severe cases, the tuba may need to be replated; a much more involved and expensive job.
Dents are worked out in the small branches with dent balls (a polished (or chrome plated) steel ball on the end of a rod or cable). On large branches and the bell, they are removed by rolling the metal between a polished steel roller and a polished iron. There are variations on the theme, such as burnishing between two polished irons.
Dent removal is more of an art than anything else. Since the area of a dent represents deformed metal, removing it involves the problem of what to do with the extra material, since the brass has been stretched (and you can't un-stretch it). Sort of like working with pie dough. A good tech can blend the dent area in so that you never see it. However, since the whole process is basically deforming metal, be aware that the playing characteristics of the instrument may change, sometimes for the better, sometimes not.