Quantifying Appearance Attributes and Monitoring Appearance
Changes  The amount of research investigating the risks of light
damage to fine art materials is very small, but the amount
directed at ethnographic and natural history materials is even
smaller. More might have been done if the fundamental properties
of many of these products were easier to characterize. museum
lighting  museum lighting  Feathers of a great horned owl (Bubo
Virginianus). Under visible light (left) and ultraviolet
illumination (right), porphyrins—pigments found primarily in new
feathers—show up as intense pink. Photo: Renee Riedler
Ethnographic Materials with Biocolorants and Structural Colors
Unlike paints and dyes, biological colors are divided into those
created by biopigments and those produced by a handful of
physical phenomena that constructively and/or destructively
interfere with reflected light. Structural colors are
notoriously difficult to measure in a repeatable manner.
Iridescence, for example, cause an angular depende