Fig. 4From: Developing a non-invasive tool to assess the impact of oxidation on the structural integrity of historic wool in Tudor tapestriesNIR spectrum of a historic wool yarn. The peak observed at 2180 nm is used to indicate the presence of proteins as it relates to different functional groups that reside along the protein backbone. Note the step circled around 1820–1840 nm where the detector changes to accommodate longer wavelengthsBack to article page