We have developed a reproducible protocol for studying the effect of microwave radiation on the mechanical behavior of Bombyx mori cocoon silk. In the course of this work, we identified multiple improvements that can be made to ASTM F 1317-98, the standard according to which microwave oven power output is calibrated.
Exposure to microwaves does not significantly affect mechanical properties of silkworm silk, if samples are kept in a desiccator after degumming (or after degumming and microwaving) and prior to testing in a dry environment. This finding contrasts with previous work in which samples were not kept in a desiccator, and were tested in a relatively humid environment.
Because the effect of microwave radiation on the mechanical behavior of silk is sensitive to ambient moisture, meaningful comparison or pooling of test results acquired in different laboratories is contingent on standardization of both the sample storage environment and the environment in which samples are tested. Interpretation of the extensive existing literature on silk mechanical properties must take account of the reality that the sample storage and testing environments are not standardized and are usually not reported.