More Adjustments and Then Finishing
After installing the three legs and the pedals, the process moves to the finish tuning. Tuning is the process of adjusting the strings to have the correct pitch to produce the musical scale. In the keys which have three strings, the middle string is tuned first. A tool called a "mute" is inserted to silence the strings on either side. The right and left strings are then tuned based on the pitch of the middle string.
In addition, a finish tuning is performed, and the action is regulated to ensure flawless movement. Here, a senior piano technician with many years of experience takes charge. The closer a piano gets to completion, the greater the requirement for a master piano technician to perform the adjustments.
Next is the voicing process. This task adjusts the hardness and resiliency of the hammer felts to alter the tone and balance the notes. Specifically, in a process called filing, sandpaper is used to smooth the surface of the hammer felt and remove irregular fuzzing, to soften the felt when it has become too compressed, and to re-shape the hammer head. For notes that are strung with two or three strings, the hammer is shaped so that it strikes each string in the same way.