As with many steps in the finishing process, each finisher will have his/her variation on technique, but Karl Kornfeld demonstrated the process to us recently. He first takes a magic marker to mark completely around the top of the tone hole. Karl uses a green marker, although he said that any color would work. He prefers not to use blue since the protective tape used on the flute is blue. He then takes a small piece of a flat file and wraps it with a piece of 1200 grit sandpaper. The flat file provides a flat surface for the sandpaper to work with in the process. He then takes the wrapped flat file and gently sands the tone hole crown until the green marker ring disappears. Karl shared, "If it's done correctly, it looks like a silver ring that is glowing green." Glowing? Well, in other words, because the tip of the magic marker is wider than the tone hole crown, a bit of marker will remain inside the tone hole -- which gives the "glow" after the green marker on the crown is sanded down. After sanding the crown, if it looks like the silver ring is not complete (spots of green still visible on the crown), that means that there may be a low spot. In this case, the crown must be leveled a bit more to make it flat. Karl said that the lowest spot on the tone hole crown determines how much leveling needs to be done.
Obviously, all this hand work takes extreme care and expertise. The exact amount of pressure to use and actual technique comes from much practice. As Karl mentioned, this process is extremely critical for seating pads properly -- and for making sure the entire flute mechanism fits and functions as it should as well!
|Marking the tone hole crown.
|Crowns marked all the way around.
|Flat file wrapped in 1200 grit sandpaper.
|Leveling the tone hole crown by sanding.
|Green ring gone (silver ring "glowing green" now).
|Green marker left on this ring shows a low spots.