Colored feathers in museum collections: A spectroscopic study of 3 bio-pigments and their lightfastness

Abstract Yellow to red feathers in ornithological and ethnographical museum collections are known to be sensitive to light exposure. However, only a few studies on the interaction of light with the color of feathers have been published. This work provides fresh insight into the sensitivity of feathers for better conservation and exhibit of ethnographic collections, with a specific focus on carotenoids, psittacofulvins and porphyrins-based feathers. A first approach was to evaluate the use of Fiber Optics Reflectance Spectroscopy (FORS) in the visible range to characterize the chemical nature of the bio-pigments. It was implemented on 19 ornithological specimens preserved in the Museum national d’histoire naturelle (MNHN) in Paris, and on assigned feathers from more than 40 objects from the collections of the musee du quai Branly - Jacques Chirac (mqB-JC). Then, microfading tests were carried out on molting feathers or picked up on dead birds. Two different setups were used in order to determine a reproducible protocol for these 3D materials. Several variables were considered including the positioning of the feather and the duration of measurements. In addition to the visible range, the near-infrared (NIR) region was also investigated to determine if the color fading is concomitant to any structural modification. Then the developed protocol was applied on some loose lumps of feathers from objects of the mqB-JC collections. The data were compared against each other and to the Blue Wool Standards fading rates.