Harp

The harp, sometimes called a plate, is one of the primary structural components of the pianos tone generating system.
It withstands up to 18-25 tons of combined pressure (produced by the strings tuned--at pitch). The plate must not only maintain the integrity of the pianos mathematical scale but also complement the tonal quality of the instrument by not impeding it with any unnecessary vibration. It must be constructed of enduring material that prolongs strength and stability.

There are two different ways to manufacture a plate. One, the traditional way, is called a sand-cast. A sand-casting allows the bell quality cast iron to harden naturally.

The second way a plate is produced is by vacuum casting. Vacuum-cast harps require less hand-finishing before being installed in a piano. This seemingly more efficient process may enable the timbre of the metal to change.

Sand-cast harps have stood the test of time.

Look at any vintage piano of note: Steinway Pianos, Mason & Hamlin, Chickering...or other fine pianos all contain
a sand-cast harp.

Schwetchen. harps are fabricated in the conventional sand-cast method.