Harpsichords and other wire-strung musical instruments were made with longer strings about the beginning of the 17th century, and so required stronger music wire than previously. Antique iron harpsichord wire was found to contain phosphorus and no carbon. In replicating antique wire it was found that low-carbon iron containing 0.16% phosphorus could be easily drawn to appropriate gauges and strengths for restringing antique harpsichords. Antique wire was analyzed by secondary ion mass spectrometry for all elements except carbon which was determined by field ion microscope atom probe. -- AATA