M. Járó - L. Költő szerk.: Archaeometrical research in Hungary (Budapest, 1988)
Analysis - WITTMANN Zsuzsa, BÉLAFI-RÉTI Katalin, DÉCSY Zoltán, ERDŐHALMI-TÖRÖK Klára, KISS—BENDEFY Márta, VASSÁNYI István, VELLEDITS Lajos: Examination of painting materials used by Mihály Munkácsy for his painting "Studio"
How could the beeswax be used on the grounded support? As a component of a material system (called ground II), was it brushed warmly? No! As Végvári wrote [7], "Munkácsy. . . painting most of his pictures, put the bitumen from the pail with his own hand. . .". The beeswax and the other materials could be kept in fluid form by oil of turpentine. Oil of turpentine consists of monoterpenes and sesquiterpenes independently of its origin [4]. The isoprene unit is (C 5 H 8 ) n , where n = 2,3 and their molecular mass are 136 and 204 respectively. These molecular ions and the molecular ion of a ketone (Cis H 2 4O/22O) of sesquiterpene can be found in the mass spectrum. The different resinous materials such as varnish resins used during the conservations could be dissolved in chloroform too. These materials are diterpenes or triterpenes [4]. In the mass spectra of the both sample parts - dissolved and not dissolved in chloroform (Figs. 4, 7) - the molecular ions can be found with molecular mass of 302,248, 234, on account of their incomplete solution in chloroform. The most important compound of the terpene resins is diterpene carbonic acid (C 2 oH 3 o0 2 molecular mass 302) in the form of isomers which depend on the origin of the resin . The oxidized products of the diterpenes are the resin acids. Thus, the diterpene carbonic acid (C20H30O2 ) forms from pimaradiene (C S H 8 ) 4 (272). Pimanthrene Ci 6Hi 4 (206) is a product of dehydrogenation of pimaric acid. We have found that the mass spectrum of sandarac — among the spectra of diterpene resins - (Fig. 4/b) contains as main molecular ions with molecular mass 302 and 272. The ions (188, (206,) 234, 248, 438,456) may belong to a triterpene resin, namely to mastic (Fig. 4/c) with small difference of the intensity and molecular mass of some ions The ions (30, 44, 70, 84, 86, 96, 111, 124, 138,154,162,170,210,224, 260) of glue from ground I can be found in the spectrum of the sample-part not dissolved in chloroform (Fig. 7). There is another material system with great molecular mass in the sample. Perhaps it is surprising here, but the mass spectrum of gum arabic (Fig. 7/a) contains the ions in question (43, 57, 68, 73, 85, 98, 114, 126). The difference of the intensity of some ions in the two spectra (Figs. 7 and 7/a) comes from the decomposition of gum arabic by • i •. • i • i • i < j < i < i • J ' • i i • i > i • i j •. ' i • 111 j 11111 11. i * 11111 ' i • i ' i » 1111 1 , 450 500 550 600 6SO 100 TSC 8QO„ /L Fig. 7 Mass spectrum of the sample part not dissolved in chloroform (from sample 2)
