Silk is made of natural protein, and can be damaged by heat, light, hydrolysis, etc. It deteriorates during burial, storage, display, studying and conservation treatment such as cleaning. Ancient silk fabrics are very precious, so their deterioration in museums has long been a concern for many conservators. To better preserve these textiles, early detection and quantitative assessment of damage is essential. Modern cultivated silk samples were artificially aged by simulating three main natural aging factors: light, heat and hydrolysis. Using these samples, the potential of viscometry for the quantitative assessment of silk damage was studied systematically by comparing with tensile strength testing. The results of this research show that viscometry is sensitive to the small changes in silk molecular weight resulting from deterioration. The technique is a useful method for the detection of ancient silk fabrics.