China's Terracotta Army Covered in Egg

April 18, 2008 -- China's terracotta army, a collection of 7,000 soldier and horse figures in the mausoleum of the country's first emperor, was entirely covered with beaten egg when it was constructed, according to German and Italian chemists who have analyzed samples from several of the figurines.

According to the research team, the egg served as a binder for colorful paints, which went over a layer of lacquer.

Co-author Catharina Blaensdorf, a scientist at the Technical University of Munich in Germay, explained to Discovery News that "egg paint is normally very stable, and not soluble in water...This makes [it] less sensitive to humidity and moisture."

Egg proteins would have also ensured the adhesion of the paint to the lacquer, while also giving the paint thickness and texture, added Blaensdorf's colleague Ilaria Bonaduce, of the University of Pisa in Italy.

For the study, which has been accepted for publication in the Journal of Cultural Heritage, the researchers took samples from warrior figurine faces, kneeling archers, swans and paint fragments found on the ground inside the 210 B.C. mausoleum. They chemically separated the flakes to isolate the ingredients, and then inserted them into a machine that determined their composition.

The researchers thought animal glue might have served as a binder, but all of the data pointed to egg instead. The pigments, they found, were bone white, lead white, cerussite (which sparkles), quartz, cinnabar, malachite, charcoal black, copper salts, Chinese purple and azurite.