Seminar May 6, 2022: Joseph Curtin, Deformation & Creep: The long-term effects of string tension

Bringing an instrument up to tension causes immediate though subtle deformations in its shape. These deformations increase over time and lead to sunken necks, distorted archings, and many other problems. The mechanism responsible, known as ‘creep,’ is inherent to many materials from plastics to concrete. Wood exhibits two varieties of creep: visco-elastic and mechano-sorptive. While both depend on initial deflection, visco-elastic creep increases sharply with temperature and humidity, while mechano-sorptive creep increases with the frequency and amplitude of humidity cycling, meaning it can proceed very quickly. This talk reviews some of the science of creep and then considers practical ways makers can reduce its effects on their instruments.