Scientific examination of mural paintings of the Koguryo tombs

Within the framework of the UNESCO workshops on the Conservation and Preservation of the Koguryo mural paintings which were held in Pyongyang in 2004 and 2005, paint samples were collected from several different tombs (Tokhun-ri, Yaksu-ri, Susan-ri, Jinpa-ri) located in the sub-urban Pyongyang and analyzed by optical, polarized and FTIR microscopy, environmental scanning electron microscopy coupled with energy-dispersive X-ray analysis (ESEM-EDX), X-ray diffraction (XRD), Pyrolysis Gas Chromatography Mass Spectrometry (Py-GC-MS) as well as Raman spectroscopy in order to characterize the composition of pigments, the execution technique adopted and the murals’ state of conservation. The first scientific results seem to suggest the adoption of a “fresco technique”, even though it’s not yet clear whether it was intentionally achieved by painters. To verify this more samples need to be analysed as well as confirmation from an historical literature survey. The external surface of all the paint layers showed the presence of a recrystallized calcite layer, with embedded clayish deposits. Traces of organic materials such as waxes, silicones and natural resins (probably applied during past restoration interventions) have also been detected. The scientific examination results guided the selection of the most appropriate conservation and restoration intervention techniques.