Conservation of the Polychromy

The terracotta figures were coated with two layers of qi lacquer before being colorfully painted. After being imbedded in humid soil for more than 2000 years, the qi lacquer is waterlogged and partly degraded. As a consequence, the lacquer shrinks and develops cracks as soon as the relative humidity decreases. Finally the lacquer, togehter with the paint layer detaches from the terracotta and gets lost.

In co-operation with Prof. H. Langhals from the Ludwig-Maximilians University in Munich two promising conservation methods were developed, the PEG and the EB method (polyethylene glycol method and electron beam method). The principle of both methods is the replacement of the water in the qi lacquer layer, combined with the consolidation of the detached lacquer to the terracotta. The respective consolidant is applied to the polychrome terracotta surface with poultices. In the PEG-method, PEG-200 with a PA-dispersion (PA: polyacrylate) is used. The hygroscopic PEG keeps the terracotta humid and therefore stabilizes the polychromy, while the PA fixes the lacquer to the terracotta. For the EB-method an electron beam accelerator, in which fragments previously soaked with a methacrylate mixture can be consolidated, is necessary. During radiation the monomers polymerize and hence consolidate the polychromy. The improvement of the described procedures, as well as the search for further alternatives, was the subject over the entire term of the project.

Dr. Beata Oginski (2004-2007)

Dr. Daniela Braun (geb. Bathelt, 2001-2004)

Dr. Ingo Rogner (1997-2001)

Ulrike Ring (1991-1993)

Prof. Dr. Christoph Herm (1995-1996)

Dr. Cristina Thieme (1991-1996)

Dr. Dipl.-Rest. Catharina Blänsdorf (1998-2007)