Degradation in Weighted and Unweighted Historic Silks

The influence of type of silk, age, and weighting agent on the physical and chemical deterioration of silk fabrics was evaluated by comparing the strength, elongation, amino acid content, viscosity, and infrared spectra of 54 undyed, historic silk fabrics with new silk plain weave fabric. Fiber fracture patterns also were characterized. Metallic elements present on the silks in various amounts, as determined by neutron activation analysis, were tin and to a lesser extent iron, aluminum, chromium, copper, barium, and arsenic. In general, tenacity, elongation, and viscosity were inversely related to the age of the silk. The variety of fiber fracture patterns in the historic silks reflected the diverse histories and causes of deterioration.