Characterization and preservation of weighted silk

The preservation of silk textiles from the late nineteenth and early twentieth centuries is one of the most difficult problems facing textile curators and conservators today. During this period, silk was treated (weighted) with metal salts to increase the weight and size of the fiber. Silk weighting is recognized as a probable cause of the rapid deterioration of silk textiles. This study provides a systematic investigation of weighted silk using visual and instrumental analysis of historic silks and a comparison of possible preservation treatments on both historic and new weighted silk.; The deterioration found on a sample group of thirty-four historic textiles (1850-1930) was characterized using a visual rating scale (1-5). The most deteriorated silks were further documented using fabric surface photographs and fiber micrographs which illustrated corresponding fabric and fiber deterioration. The types and amounts of weighting agents present were characterized using several analytical methods. Neutron activation analysis revealed that light colored silks contained tin and dark colored silks contained iron in amounts of over 10,000 ppm. Amounts of lead over 800 ppm and arsenic over 500 ppm were indicated by inductively coupled plasma analysis.; To identify a possible preservation treatment, eight formulations were applied to historic silk and weighted new silk: a deacidification agent, four antioxidants and a combination of antioxidants. Both historic and new silks were compared to untreated controls using spectrophotometer color change measurements. The new silks were exposed to different amounts of light and also evaluated for strength loss. The historic silk testing indicated that only the deacidification agent and the ultraviolet light absorber produced acceptable color change levels. The results of new silk testing indicated that only the ultraviolet light absorber retarded deterioration as measured by both tensile strength and yellowness values. The other antioxidants retained strength but increased yellowing. The deacidification agent retarded yellowing but had no effect on strength. A color acceptability rating by a panel of textile experts confirmed treatment yellowness measurements.; This study provided a systematic approach to the characterization of weighted silks. Preservation treatment research indicated that an ultraviolet light absorber has potential in retarding deterioration. The identification of a preservation treatment will have a profound effect on the museum community, however, additional research will be necessary.