Restringing is a major aspect of piano restoration. Strings generally are not swapped out periodically on a piano as they are on lower tension instruments such as guitars, violin, etc. The reason for this is twofold. First, piano wire is heavy gauge, high-quality, high carbon steel. By nature, the material lasts a long time. Second, it usually is not wise to restring without considering replacing at least bridges and pinblock. The reason for this is topic for another discourse. There are exceptions to this rule in some unique circumstances. There are two types of wire common in industry that share the same calibration. One is music wire used in machine shops, cable construction, and other applications. In pianos, Piano Wire is used. Both are similar in that they are manufactured according to international gauge standards. The difference is that Piano Wire is high carbon, high-tensile wire manufactured to higher purity standards.Pianos utilize upwards to 16 different diameters of wire. The tenor and treble wires are plain wire of various diameters, while the bass section is solid core wire with one or two layers of wrapping (generally copper), to add the required weight while maintaining flexibility.The design of each model is different according to the stringing scale (design) of the piano.When rebuilding, in most cases the string scale is copied from the original. In cases where improvement can be made according the craftsman’s preference, or when strings are missing, mathematical formulas are used to calculate the correct diameter of wire. The piano designer uses several formulas to establish the Tension, Length, Pitch, and Weight. Examples of the formulas used are listed below:

TENSION: T = P2L2W over 675,356

LENGTH (speaking length): L = 821.8 √T over P √W

PITCH: P = 821.8 √ T over L √ W

WEIGTH (weight of string): W = 675,356 T over P2 L2

Restringing is one of the final stages in restoration of the piano’s super-structure. It is a tedious task and rather hard on the hands. Wire must be cut from spools to length, wrapped around tuning pins and forcefully hammered into the pinblock, one at a time. This stage reveals the accuracy of the rebuilder’s work. If all previous steps were done correctly the instrument will have correct intonation and dynamics. There is no easy way to retract previous work at this point. For myself, I trust the science, my own skills, and then say a prayer that everything is right. Thankfully, this instrument pictured (you’ve seen previous stages in other posts) has turned out exceptionally well.The piano will have a first tuning called “chipping”. Since the action is not yet in the instrument the strings are plucked, or chipped, by hand to sound. This will get the notes in chromatic sequence and establish uniform tension across the range of the piano. Following chipping, the instrument will receive five rough tunings before it can be fined tuned.The aesthetics come to life once the piano is restrung. I passionately believe there are few man-made things whose beauty come anywhere close to that of the inside of a piano.Pictures:Completed StringingPin Block DrillingTuning PinsWrapping String Coil Piano Wire Bass StringsPartial Plain Wire Stringing Complete