The Cast-Iron Frame

A one-piece iron plate let pianos take thicker strings and higher tension, and the instrument filled the hall.

Related

RomanticPianoTimbreModern

The strings of a wooden-framed piano cannot be pulled too tight, or the frame bends. A one-piece cast-iron plate allowed thicker strings at higher tension, and for the first time the piano could fill a large hall.

Time and place

Boston, 1825. The maker Alpheus Babcock patented a one-piece cast-iron frame, first used in square pianos. Chickering applied it to grands in the 1840s, and Steinway combined overstringing with a full plate in 1859. European makers followed later, adopting it widely in the second half of the century.

What happened

Total string tension rose throughout the nineteenth century, and wooden frames braced with iron bars could not keep up. The cast-iron plate is a ribbed metal bed to which the pin block, hitch pins and soundboard are fixed, so the frame rather than the wooden case carries the load. Strings could then be thicker and longer, the bass deeper, the sound louder, the tuning more stable. Overstringing slanted the bass strings across the longer treble strings, shrinking the case while lengthening the scale. Manufacturing became industrial, with casting, foundry work and assembly at the centre of the piano factory.

What changed

The piano moved from the parlour to the concert hall. Composers wrote for larger rooms, piano parts could stand against violins and orchestras, and Liszt and later Rachmaninoff wrote that volume into their music. Piano making became heavy industry, with output and exports growing alongside the railways. The price was a more uniform tone, as the light, transparent pianos of the early nineteenth century retreated into historical performance. The grand piano in a hall today still rests on a structure settled in the 1850s.

Listen for the turn

Begin with Chopin's First Ballade, written when tension was lower, its sound carried by colour and rubato rather than power. Then Liszt's Gnomenreigen, where rapid soft passages and sudden accents must stand in a hall, the iron frame beginning to do its work. Finally a Rachmaninoff prelude, thick in the bass and long in resonance, the voice of the modern iron-framed instrument. In sequence, they trace the piano from room to hall.

Related

This turn belongs to Romantic and leads toward Modern; see Piano and Timbre.

Sources

• Grove Music Online, entry Pianoforte — iron frame and patents checked, not quoted
• The New Grove Dictionary of Music and Musicians, 2nd ed., entry Steinway — overstringing checked, not quoted

Used for fact-checking only; all prose is original.