Overspun strings from 18th- and 19th-century English square pianos

Abstract

Analyses of overspun strings identifi ed the base wire as yellow brass of the maximum composition achievable by the traditional process of cementation, but the red wire wrapped around the 18th-century samples differed from that of the 19th-century wire in two respects: the overspinning in the 18th-century samples was silvered and contained only 1.4% zinc, an amount adequate to deoxidize
copper but not enough to strengthen it. The 19th-century wire was not silvered but contained 6% zinc, allowing the wrapping to take a permanent set. It is proposed that the silvering on the 18th-century samples may not be simply decorative but a practical means of maintaining mechanical contact between the two wires.