Piano Materials

This Piano Materials article takes a brief look into some curiosities about the reasons behind the usage of different materials in piano construction.

Many parts of a piano are made of materials selected for extreme sturdiness. In quality pianos, the outer rim of the piano is made of a hardwood, normally maple or beech. According to Harold A. Conklin, the purpose of a sturdy rim is so that "the vibrational energy will stay as much as possible in the soundboard instead of dissipating uselessly in the case parts, which are inefficient radiators of sound." The rim is normally made by laminating flexible strips of hardwood to the desired shape, a system that was developed by Theodore Steinway in 1880.

The thick wooden braces at the bottom (grands) or back (uprights) of the piano are not as acoustically important as the rim, and are often made of a softwood, even in top-quality pianos, in order to save weight.

The pinblock, which holds the tuning pins in place, is another area of the piano where toughness is important. It is made of hardwood, and generally is laminated (built of multiple layers) for additional strength and gripping power.

Piano strings (also called piano wire), which must endure years of extreme tension and hard blows, 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. The bass strings of a piano are made of a steel core wrapped with copper wire, to increase their flexibility. For the acoustic reasons behind this, see Piano acoustics.

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 loss of energy to the desired (efficient) channel of sound transmission, namely 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 during cooling. The inclusion in a piano of an extremely large piece of metal is potentially an esthetic handicap. Piano makers overcome this handicap by polishing, painting, and decorating the plate; often plates include the manufacturer's ornamental medallion and can be strikingly attractive.

The numerous parts of a piano action are generally hardwood or plastic. The choice between these two materials is controversial. Some varieties of plastic, incorporated into pianos in the 1950's and 1960's, were clearly disastrous, crystallizing and losing their strength after one or two decades of use.

The Steinway firm once used Teflon, a plastic, for some action parts, but ultimately abandoned the experiment. More recently, the Kawai firm has built pianos with action parts made of more modern and effective plastics; these parts have held up better and have generally received the respect of piano technicians.

View from below of a 182-cm grand piano. In order of distance from viewer: softwood braces, tapered soundboard ribs, soundboard. The metal rod at lower right is a humidity control device.The part of the piano where materials probably matter more than anywhere else is the soundboard. In quality pianos this is made of solid spruce (that is, spruce boards glued together at their edges). Spruce is chosen for its high ratio of strength to weight. The best piano makers use close-grained, quarter-sawn, defect-free spruce, and make sure that it has been carefully dried over a long period of time before making it into soundboards. In cheap pianos, the soundboard is often laminated; i.e. made of plywood.

Piano keys are generally made of spruce or basswood, for lightness. Spruce is normally used in high-quality pianos. Traditionally, the white keys were covered with strips of ivory, but since ivory-yielding species are now endangered and protected by treaty, plastic is now universally used. The Yamaha firm innovated a plastic, since imitated by other makers, that mimics the feel of ivory on the player's fingers.

The requirement of structural strength, fulfilled with stout hardwood and thick metal, makes pianos heavy. Even a small upright can weigh 300 pounds (136 kg.), and the Steinway concert grand (Model D) weighs 990 pounds (480 kg). The largest piano built, the Fazioli F308, weighs 1520 pounds (691 kg).

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