Piano Hammer Reglueing
Occasionally on an older piano that has been subject to dry conditions, or one that experiences heavy use, it is not uncommon for the glue joint where the hammer meets the hammer shank to become loose, usually indicated by a noticeable clicking sound when that note is played. Heating the joint facilitates the removal of the hammer for piano hammer reglueing.
Top image shows before piano hammer reglueing, bottom image shows after reglueing
The old glue is removed by sanding, because new glue does not like to stick to old glue, and new glue is applied. Here is an example of hammer reglueing on an older Young Chang grand piano I serviced recently in Rockland County NY. The black coloring is a result of the heating process and is wiped clean upon completion of the repair.