|The Plate / Harp.
So strong that it can withstand twenty tons of string tension! So precise that it can provide a minutely accurate framework for the tone producing elements! This is the challenging function of the plate. Only one material has been found capable of being worked to intricate tolerances, yet so rigid that it will not yield. This material is Cast Gray Iron. The plate is designed to take into account every detail of the scale such as space for the bridges and anchor points for all the strings and is fitted exactly to the dimensions of the rim. The entire grand piano plate is cast in one piece, an assignment few foundries can handle. After the plate is removed from the mold, it must be uniform in texture and totally free from shrinkage strains. It is chipped, ground and filled. The casting next is thoroughly sealed with baked on japan, hand rubbed to a smooth surface, then sprayed with gold finish and, as a final touch, lacquered to a rich golden luster. The strings are made of special steel wire, precision drawn through diamond dies with an ultimate tensile strength of from 300,000 to 400,000 pounds per square inch, the strongest made. In the bass, more weight is needed to make the strings vibrate more slowly and thereby produce the lower pitches. This is accomplished by wrapping an additional copper wire around the steel wire.
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