"Investigating Structurally and Pigmentary Colored Featherworks via Noninvasive Methodologies" ACS Omega
The kingfisher's brilliant blue feathers were once used like paint to create works of art. The technique, known as tian-tsui, was popular during China's Qing Dynasty. And because tian-tsui uses delicate feathers, previous scientists struggled to study them using traditional analytical techniques. So, researchers reporting in ACS Omega developed new methods of investigating these featherworks without harming them. The team found that multiple bird species and layered pigments provided a one-of-a-kind palette.
Color in artworks and artifacts is a complex phenomenon occurring across material class and length scales from macro to nano." - Madeline Meier
The shades of blue in kingfisher feathers are the result of a phenomenon called structural color. Rather than being created by pigment molecules, structural color is created by tiny, ordered structures in the feathers that interact with light to create the observed coloring - in this case, blue or purple. To gain insights into several featherwork pieces and the feathers that went into making them, Madeline Meier and colleagues combined different imaging and spectroscopy techniques that rely on the ways the feathers reflect and scatter light.
The Field Museum, Image No. A113975c, Cat. No. 118334, Photographer John Weinstein (screen) and Madeline Meier (inset)
The team analyzed a decorative tian-tsui screen estimated to date from the late 18th to the early 19th century that features intricate scenes in a variety of colors. In one panel, analysis revealed that the blue feathers belonged to the common kingfisher, and the purple came from the black-capped kingfisher. The green feathers had different nanostructures than the blue feathers, leading the researchers to conclude that the green ones belonged to another bird entirely: the mallard duck. Unexpectedly, they discovered that the magenta areas contained mercury(II) sulfide - likely from a red pigment called cinnabar that was used in Chinese artworks of this era - layered beneath purple feathers from the black-capped kingfisher.
"Color in artworks and artifacts is a complex phenomenon occurring across material class and length scales from macro to nano," adds Meier. "It really illustrates the skill and material knowledge that went into fabricating these beautiful works."
Headdress (清朝 点翠头饰), Qing dynasty (1644 - 1912), 18th - 19th century China. Promised gift of Barbara and David Kipper. The Art Institute of Chicago.
Next, the researchers will apply the techniques to other tian-tsui artworks, including a series of headdresses that date from the 18th and 19th centuries. They'll also conduct further research, using synchrotron methods, to more deeply understand how nano-sized changes to feather structures lead to changes in perceived color. The team hopes this work can inform future cultural heritage research into these understudied artworks.
This project was conducted at the Center for Scientific Studies in the Arts in collaboration with the Field Museum of Natural History and the Art Institute of Chicago. This work made use of the EPIC facility of Northwestern University's NUANCE Center, which has received support from the IIN and Northwestern's MRSEC program. The authors acknowledge funding from the Mellon Foundation, the Sarah Cao Endowed Fund, the Jianfeng and Kaili Family Endowment Fund, the Wang Family Endowed Fund, and the Zhang Family Charitable Fund.
