The main reasons for having new strings installed in a piano are if the piano will not stay in tune, or to provide access to the soundboard and bridges for repair. However, on a grand piano it is also cosmetic. The inside of a grand when properly is as beautiful as the outside. With beautiful wood tones, silver and copper strings accented with bright felt and shinny tuning pins.
Piano restringing is not for the novice. A piano in tune has approximately 20 tons of tension on the frame and metal plate. Each piano has a sequence in loosening the string tension so unequal tension is not asserted on the cast iron plate (harp). Cast iron is very strong , however it is not flexible. The wrong stress will crack the plate and render the piano virtually useless.
After the piano has been disassembled, the restringing process begins with gauging of all the strings. All pianos have a certain scale, which means, from the highest treble string to the lowest tenor string the strings are graduated in thousands of an inch. It’s very important to use the exact gauge of string intended for that instrument so as not to exert improper tensions in the wrong areas. The string tension is now lowered to remove all tension from the plate, again loosening in the proper sequence so as not to exert uneven tension. Now the strings, tuning pins, plate bolts, and plate can now be removed.
The soundboard and bridge repair can now be addressed . Any lose ribs are re-glued to the soundboard and spruce shims are glued into any soundboard cracks. The bridge caps are now scraped and recoated with graphite, and any bridge repair is now preformed. The soundboard and bridges are then refinished.
The metal plate is then cleaned, sanded, and sprayed with a golden bronze color. New pin block material is now installed along with the refinished metal plate. Plate mounting screws are shined and sprayed and then installed . Tuning pin holes are now drilled and new strings, pins , pin bushings, dampers and string felt are now installed.
The piano is then slowly brought up to tension with 4 chip tunings and 2 final tunings.