Microscopic analysis, the only sure way to identify fiber content, is essential for dating fabric and learning when fibers began being used. For example, evidence of acrylic yarn dates a quilt to the 1950s or later. Chemical solubility tests detect synthetic fibers' composition. Evidence of nylon, for example, proves a quilt was sewn after 1940, Crews said. Thin layer chromatography helps identify chemical compounds in dyed fabrics.
Researchers often examine fabrics with UV-visible spectro scopy, which uses light to determine dyes.
All this helps establish when quilts were sewn and reveals information about technological developments. More accurately dating quilts helps determine monetary and historic value, Crews said. Crews and her Department of Textiles, Clothing and Design team already are revising quilt history. Crews and Jenny Yearous, a former graduate student and now curator of collections at the North Dakota State Historical Society, have used some James quilts to shave at least a decade off previously established quilt-making timelines. Most experts assumed quilters began using sewing machines in about 1860, Crews said.