Preparation of Reference Samples from Biological Sources
Bulk reference samples will be prepared from each biological source, and historic recipes will be used when available. When unavailable, modern laboratory practice, based on aqueous extractions and fermentations only, will be used to prepare the samples. Dyeing of wool and silk will be performed with or without preliminary mordanting with alum. Pigments will be prepared on a hydrated aluminum oxide base. Paints will be prepared by suspending pigments in a diluted animal glue medium or by concentrating the dye extract and adding glue.
All preparations will be documented in specifically designed data sheets to ensure reproducibility and later large-scale production. Initial small-scale production will allow for refinement of procedures and confirmation of the biological source by Liquid Chromatography-Photodiode Array-Mass Spectrometry. Finally, large-scale productions will be prepared. All preparations and reference samples will be cataloged in a database.
Wall Paintings Mock-Ups
The Dunhuang Academy and the GCI have been studying the wall paintings in Cave 85 at the Mogao Grottoes for nearly two decades. The compositions of the plaster walls, ground layers, and inorganic paint layers are well researched and understood. The Dunhuang Academy has prepared one hundred fifty plaster wall painting mock-ups using clay and other materials available on site. Each coupon has a traditional ground layer applied to half of its surface and seven strips of common inorganic paints used in the grottoes.
For shipment of the coupons to the GCI laboratories, the Getty Museum Preparations Department constructed a specially designed crate to protect the fragile coupons during road and air transit. Designed by Bruce Metro and Rita Gomez, the 42" x 26.5" x 32" crate was built by Gomez and Cary Stehle and shipped from the Getty to the Dunhuang Academy in January 2007. Under the supervision of Dr. Fan, the coupons were loaded into the crate and sent to the GCI, arriving in March 2007.
At the GCI, organic paint prepared with the reference pigments will be applied to the mock ups. The plaster, ground, inorganic paints, and lake pigments provide crucial combinations to evaluate an analytical scheme. From each biological source, five mock-ups will be produced: one for investigating the best possible analytical procedure(s), one for natural ageing in the grottoes, one for accelerated ageing at the GCI, and two for the GCI reference collection for future research.
Page updated: January 2011