Caroline Solazzo

Proteomics characterization of membrane metal threads used in historical textiles

Caroline Solazzo §; Timothy P. Cleland §; Aleksandra K. Popowich £

§ Smithsonian's Museum Conservation Institute, 4210 Silver Hill Road, Suitland, MD 20746, USA; £ Department of Chemistry, University of Alberta, 11227 Saskatchewan Drive, Edmonton, Alberta T6G 2G2, Canada

Membrane metal threads, which were made by coating animal skin (leather, parchment, vellum) or membranous material (intestine, peritoneum, stomach) in a thin layer of metal, were the most common variety of metal thread used in textiles from the 13th century onwards. Membrane standards, made from metal-coated or metal-free pig peritoneum or cow intestine, with or without egg-based adhesives, were used to develop a method for small scale sample extraction and nano liquid chromatography Orbitrap tandem mass spectrometry (nanoLC-Orbitrap MS/MS) analysis. Collagen peptides were used to determine the animal species of origin, while tissue specific proteins, such as smooth muscle proteins detected in the intestine standards, were used to distinguish between membrane types. Additionally, analysis of standards with a thin layer of egg adhesive allowed for the distinction between egg white and yolk adhesives. Proteomics analysis of a thread from a 14th century Italian textile revealed that the ancient thread was made of cow tissue, likely either intestine or stomach membrane, without the use of egg-based adhesives.

An extensive program for the characterization of membrane metal threads in medieval textiles is being developed at the Museum Conservation Institute. In addition, the composition of membrane metal threads is determined in other types of textiles: here we will present a study of the materials and fabrication of six traditional Chinese children’s hats. The handmade hats are dated early twentieth century and are predominantly in the form of animals; they are exquisitely made using a variety of decorative techniques including embroideries, appliques, silvered and gilt leather strips in addition to metal-wrapped threads. Children wore them from infancy to early teens for protection against not only cold but also evil spirits as well as to bring good health and fortunes.