CONSUMER INFORMATION GUIDE
The piano back is composed of a number of vertical
wooden posts, extending almost the full height of the piano, which are braced by
other horizontal pieces top and bottom. This framework is jointed and glued
together in various ways, each method aimed at attaining the greatest structural
support possible from the materials used. Woods used for piano backs include
pine, spruce, and ash.
The metal plate is a gray-iron casting with
tremendous compressive strength that is needed to withstand the enormous overall
tension of the strings. An additional desirable property of gray-iron is its
damping ability (the ability to absorb vibration without movement or
transference of sound, such as ringing). Gray-iron also exhibits high resistance
to metal fatigue.
The tuning-pin block (wrest plank) of a vertical
piano extends horizontally across the upper framing of the wooden piano back and
is securely glued to the latter. The tuning-pin block, made up of several or
many laminations of hard rock.