The Structure of the Celesta
Celesta hammer shanks
Hammer shank design
The shanks of hammers in grand pianos are vertically thick and very hard. In contract, the shanks of hammers in celestas are thin vertically but thick horizontally, and supple. They are similar in shape to the soft mallets used for playing sound bar percussion instruments such as the marimba or vibraphone (metallophone).
Sound bars are made high-carbon steel, a very hard metal also used in automobile suspensions.
The wooden parts of hammers are made from birch, while the tips are made from felt. The surface of the felt hardens after some time due to striking the hard sound bars, flattening the sound. Just as with tuning a piano, the pins must be replaced and the hammers sanded to bring the instrument back to its proper springy feel.