Ultraviolet-induced visible fluorescence and chemical analysis as tools for examining featherwork

Feathers are found in cultural heritage collections of tribal arts from the Americas, Africa, and the Pacific as well as in contemporary art, European and American fashion, and in taxidermy and ornithology specimens. Although museum conservators routinely evaluate feathers by looking at insect damage and mechanical wear, as well as fading as evidence of light exposure, examination of feathers for visible fluorescence under an ultraviolet source is atypical. Recent research by both the authors and bird biologists indicate that ultraviolet fluorescence examination can provide valuable information about the identification and pigmentation of feathers found in museum collections. A number of feather pigments, including psittacofulvins found only in red and yellow pigments in birds in the Psittaciforme family, as well as porphyrins found in rusty brown owl plumage, may be identified by their specific ultraviolet-induced visible fluorescence. Feathers whose pigments are not directly fluorescent may still undergo appearance changes under an ultraviolet source as a consequence of light aging. Fluorescence is demonstrated to be an early marker of chemical change, and can be used to detect such change before it can be measured colorimetrically. The authors evaluate different methods of analysis, including ultraviolet-induced visible fluorescence, reflectance spectroscopy, fluorescence spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, gas chromatography/mass spectroscopy, and rates of pigment extraction for detecting light-induced physical and chemical changes in feathers. Results indicate that ultraviolet-induced visible fluorescence may be the most sensitive indicator of light-induced degradation. Museum featherwork, some with records of estimated display, was found to display ultraviolet-induced visible fluorescence changes analogous to photoaged feather samples.