Authors: Kamilla B Kalinina (corresponding author) ; Sander Habets ; Evelina A Tarasova ; Svetlana L Petrova 
Vladimir Beklemishev graduated from the Saint Petersburg Imperial Academy of Arts with a Grand gold medal in 1887 . He was a pensioner of the Academy of Fine arts in Paris and Rome in 1888-1892. He made the sculptural group "Fugitive Slave" in Italy in 1890-1891. The undoubted source of inspiration for V. Beklemishev was ?Slaves? by Michelangelo (Florence, Museum of the Academy of fine arts).
This sculpture was created under the influence of the anti-slavery novel ?Uncle Tom's Cabin? by American author Harriet Beecher Stowe, who was very popular this period of time. Together with the paintings of famous Russian artists such as I. I. Levitan, V. A. Serov, I. E. Repin, V. I. Surikov, sculptural group "Fugitive Slave" was presented at the World's Columbian exposition in Chicago in 1893, devoted to the 400[sup.th] anniversary of the discovery of America by Columbus . After the exposion, the sculpture was gifted to the Museum of Saint Petersburg Imperial Academy of Arts in 1918, which later donated it to the State Museum of the Great October Revolution in 1930. After the Second World War (1941-1945), the Museum of the Great October Revolution got its own building (a mansion of M. Kshesinskaya) where "Fugitive Slave" was to moved to. The sculpture group was however heavily damaged during this transition. As a consequence of this damage, the decision was made for the sculpture to be stored between walls of the Eastern Gallery staircase of the Winter Palace and the Church in February 22, 1947, as explained by a note that was found with the statue. No other record of this decision was made, so in time, the location of the ?Fugitive Slave? sculpture was forgotten and the statue was eventually considered lost or even destroyed. However, in April 2010, while performing routine electrical work, the sculpture group was once again discovered, virtually in the same state as it was stored decades before.
The sculpture is made from gypsum and coated in a bronze imitated covering. At the moment of finding, the sculpture was heavily damaged and needed serious restoration, including repairs of the bronze imitated layer. This situation permitted us to do a detailed examination of the materials and techniques used in making this bronze-like covering.
This paper examines the pigments and binding media by used Vladimir Beklemishev for creating the bronze-like layers.
The study was performed on several samples from different parts of the sculpture by means of optical microscopy under visible illumination, Scanning Electron Microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (SEM-EDX) and Gas chromatography-mass spectrometry (GC-MS). Optical microscopy and SEM of the sample cross-sections revealed the layer by layer build-up of each sample. The combination of optical microscopy and SEM with EDX, allowed for identification of most of the pigments that were used. GC-MS was used for the analysis of proteins, glycerolipids, waxes, and terpenoid resins. This enabled various organic materials to be identified by marker recognition, molecular profile identification, and quantitative evaluation.
Materials and methods
A Trace GC System Gas Chromatograph (ThermoFinnigan, USA), coupled with a Mass Selective Detector single quadrupole mass spectrometer equipped with a Programmed Temperature Vaporization Injector (PTV) was used. The mass spectrometer was operated in the EI positive mode (70eV). The MS transfer line temperature was 270[degrees]C and the MS quadrupole temperature 170[degrees]C. For the gas chromatographic separation, an HP-5MS fused silica capillary column (5%diphenyl-95%dimethyl-polysiloxane, 30m x 0.25mm i.d., 0.25mm film thickness, J&W Scientific, Agilent Technologies, Palo Alto, CA, USA) coupled with a deactivated silica pre-column (2m X 0. …