The cleaning of a number of 18th-century Boucher tapestries woven in wool and silk at the Beauvais workshops provided an excellent opportunity to evaluate the treatment on the strength of the silk fibers. The authors describe the unique problems inherent in achieving statistically reliable data from restricted sampling on a historic artifact. The results of this empirical study indicate that, at least with the Boucher tapestries, it is extremely likely that the silk threads have been strengthened.