AIC's 42nd Annual Meeting

Feathers are found in cultural heritage and scientific research collections of tribal arts from the Americas, Africa, and the Pacific as well as in contemporary art, European and American 18-19th century fashion, and in taxidermy and ornithology specimens. While 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 nondestructive ultraviolet fluorescence examination can provide valuable information about the identification and pigmentation of feathers found in museum collections, but must be used with caution as both light exposure and adventitious materials may compromise fluorescence. The authors also evaluate different methods of chemical analysis for detecting light induced chemical changes in feathers.

Recent research conducted jointly by UCLA and the Getty Conservation Institute illustrated the importance of identifying feather pigmentation systems in the design of a preventive strategy. The difference in susceptibility to fading of undyed feathers can be a tenfold dose depending on the colorant systems present in the feather and the emission spectrum of the light. Feathers with color derived from the scattering of light through small scale feather structures are known to be more light stable than feathers with coloration based on biological pigments. 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. The Psittaciforme family includes culturally significant birds such as parrots and macaws and cockatoos, whose plumage comprises not only red and yellow feathers but also green feathers colored by mixtures of structural colors and psittacofulvins.

Feathers that are not directly fluorescent may still undergo appearance changes under an ultraviolet source as a consequence of light aging. Such changes are not readily measured colorimetrically as they may result in chemical and not appearance changes. The authors will describe a variety of analytical techniques applied to light aged feather samples in order to present the most sensitive methods for detecting chemical changes that parallel fluorescence changes.