In June 2006 the Getty Conservation Institute and conservation scientist Jan Wouters launched the Asian Organic Colorants project, a collaborative scientific research project to identify traditional Chinese organic colorants. The project aims to develop a strategy for the analysis of organic colorants used as textile dyes and organic pigments in Asia. The Dunhuang Academy in Mogao, China, and the Wall Paintings Conservation Department of the Courtauld Institute of Art, London, are also participating in the project.

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Detection and identification of traditional Chinese organic colorants present a challenge, not only because of the relatively low concentration of these colorants compared with inorganic pigments and binding media but also because many of the biological sources used to create them have not been well studied. Much less is known of these colorants than of the dye and organic pigment sources used in Europe and the Americas.

A review of published literature has identified more than one hundred biological sources, including fresh and dried plants, resins, and insects historically used as colorants in China and surrounding regions. Based on their frequency of citation, over twenty genus-level sources have been selected for further research. The Asian Organic Colorants project will create reference samples from these selected sources on organic and inorganic substrates for study at the GCI laboratories. Lake pigments and dyed silk and wool yarns will be analyzed through liquid chromatography with a photodiode array UV-Vis detector and mass spectrometer detector (LC-PDA-MS). Noninvasive and low-invasive techniques will also be used to develop a systematic strategy for the analysis of the colorants. From this analysis, the project will create analytical databases and disseminate this information to the conservation community.

The results of this project will complement the extensive research conducted on wall paintings in Cave 85 at the Mogao Grottoes in Dunhuang, China, by the GCI and the Dunhuang Academy (see Conservation, vol. 14, no. 2). The work at Mogao provides a unique opportunity to develop wall painting mock-ups for the evaluation of organic pigments and paints.

At Cave 85, conservators have identified mineral pigments and binding media in the paintings and have found evidence that organic colorants or lake pigments were also used. The Courtauld Institute of Art will provide critical expertise to the project on the use of historic paints in the Mogao Grottoes.

For more information visit the Asian Organic Colorants and wall paintings conservation project Web sites.