dependent on springs which are prone to wear and tear. Upright pianos have the
advantage over grand pianos that they are more compact and do not need a spacious room.
Many parts of a piano are made of materials selected for their sturdiness. In quality
pianos the outer rim is made of a hardwood, normally maple or beech, so that the
vibrational energy will tend to stay in the soundboard rather than dissipating. The rim is
normally made by laminating flexible strips of hardwood to the desired shape, a process
that was developed by Theodore Steinway in 1880.
The thick wooden braces at the bottom of grand pianos, or at the back of upright pianos,
are not as acoustically important as the rim and are often made of a softer wood to save
weight.
The pinblock, which holds the tuning pins in place, is made of laminated hardwood, often
maple, and generally is laminated for additional strength and gripping power.
Piano strings, also called piano wire, must endure years of extreme tension and hard
blows and are made of high quality steel. They are manufactured to vary as little as
possible in diameter since all deviations from uniformity introduce tonal distortion. For
acoustic reasons, the bass strings of a piano are made of a steel core wrapped with copper
wire to increase their flexibility.
The plate, or metal frame, of a piano is usually made of cast iron. It is advantageous for
the plate to be quite massive. Since the strings are attached to the plate at one end, any
vibrations transmitted to the plate will result in a loss of sound transmission to the bridge
and the soundboard. Some manufacturers now use cast steel in their plates, for greater
strength. The casting of the plate is a delicate art, since the dimensions are crucial and
the iron shrinks by about one percent in cooling.
The inclusion in a piano of an extremely large piece of metal does not look good so piano
makers overcome this handicap by polishing, painting and decorating the plate. Plates
often include the manufacturer’s ornamental medallion and can be strikingly attractive.
In an effort to make pianos lighter Alcoa worked with piano manufacturers, Winter and
Company, during the 1940s to make pianos using an aluminium plate. The use of
aluminium for pianos, however, did not become widely accepted and was discontinued.
The numerous parts of grand and upright pianos are generally hardwood, such as maple,
beech or hornbeam. After World War II plastics were incorporated into some pianos but
these proved disastrous because they crystallised and lost their strength after only a few
decades of use. In the late 1940s Teflon, a synthetic material developed by DuPont, was
used by Steinway instead of cloth but the experiment was abandoned owing to an
inherent ‘clicking’ which developed. In addition, Teflon was ‘humidity stable’ whereas
the adjacent wood parts would swell and shrink with humidity changes.
The Kawai firm has built pianos with action parts made of more modern and effective
plastics such as carbon fibre and these parts have held up better.