A Transylvanian Diptych Wooden Icon: Wooden Support and Painting Materials Investigations

Transcription

1 A Transylvanian Diptych Wooden Icon: Wooden Support and Painting Materials Investigations IOAN BRATU 1*, ZAHARIE MOLDOVAN 1, IRINA KACSO 1, CONSTANTIN MARUTOIU 2, LAURA TROSAN 3, VICTOR CONSTANTIN MARUTOIU 2 1 National Institute for R&D of Isotopic and Molecular Technologies, Donath Str., Cluj-Napoca, Romania 2 Babes-Bolyai University Cluj-Napoca, Faculty of Orthodox Theology, 18 Avram Iancu square, Cluj Napoca, Romania 3 Ethnographic Museum of Transylvania, Cluj-Napoca, Romania In order to preserve a wooden icon belonging to the Transylvanian Ethnographic Museum collection the scientific expertise of the wooden support and of the picture materials (ground, pigments, binder and varnish) used for the Virgin Mary with the Child and Diptych diptych icons (8228 inventory number) was performed by FTIR spectroscopy, EI-MS spectrometry and DSC thermal analysis. FTIR spectroscopy and DSC methods offer information about the wooden support whereas EI MS and FTIR methods were employed for binder, varnish and pigments structural characterization. These structural data can be correlated with the artistic, theological and historical analysis of this religious patrimony object. Keywords: orthodox icons / lime wood / wood fungal attack / painting materials / FTIR / mass spectrometry In the Romanian provinces, especially Moldavia and Transylvania, the icons have met a special development, displaying personal traits with certain notes of originality. As concerning the technique the majority of icons from these spaces are worked in tempera on wood, assimilating with the occidental painting on easel [1, 2]. There were also icons in caustic and mosaic, bone icons, ivory icons, steatite or wooden icons, sculpted, knocked, engraved in metal or precious metals. However, in the Romanian Counties, the wooden icons represent the majority. The painting is made on wood in the shape of an icon and represent the movable memorial, or directly on the church wall (the non-movable memorial). The painted memorial can be encountered in churches inside the altar s apse, in the area of the altar or behind the altar table [3-6]. As an icon body the most usual material used was the wood and the painting technique was tempera [7-9]. In Transylvania, in the XVIII century, the painting has evolved on the line of post-byzantium tradition, the icons differentiating themselves through particular stylistic traits connected to typology, models, chromatic range, and decoration that place them in different geographic areas. The description of the wood, of the base, the information related to the technique and pigments are all motioned in the slip, but on the basis of a visual analysis. Many times, the person who writes the slip can not make very exact determinations. That s why the gathering of evidence for future treatments of preservation or interventions on restoring the icon [10-15]. The icon 8228 (fig. 1a) is a Diptych Wood Icon. Virgin Mary with Baby Jesus on the central panel. Information from the analytic slip reveals the fact that the date of the icon is somewhere near the XIX th century. The dimensions of the icon are: 31.7/49.5/3 cm panel, 21/32.5/2 cm door (fig. 1b). Technique: oil on wood, sizing layer, central panel is composed of a wood piece which is continued on the sides and in the superior side with vegetal ornaments, sculpted and painted. Fig. 1 Diptych Wood Icon: Virgin Mary with Baby Jesus (MDP, a); Diptych, interior, 8228 (Ic.P, b) Conservation state: Back side - thick wood panel, composed of one piece of wood; -the panel I covered with a layer of sizing on the back; -curbing tendency, with the concavity inside the panel; -metal hanger on the superior side, recently added; -raft in all of the thickness of the wood fiber, on a length of 8.5 cm starting from the inferior cant. Front side -a single wood door, attached to the panel with two leather hinges and metal nails (the hinges are rigid and deteriorated); -the door of the diptych is painted on the exterior; -adherent grime deposits, the browning of the painting layer the fading of the colors; -painting layer lacking in different areas and of different dimensions -areas of cracks in two waters, especially in the halo area and in the decorative areas sculpted in wood; -multiple inchoate rifts starting from the inferior cant of the panel; * ibratu@gmail.com; Tel.:

2 -on the interior side of the door and on the panel, paper is applied having the role of memorial; -dust and grime deposits on the interior of the door and of the panel; -yellow and inflated paper; -the writing is kept in a good conservation state; -brown color stains. There are already several publications [16-23] dedicated to the use of analytical techniques in art objects and conservation studies. The aim of this paper is to investigate the wooden support status and the painting materials of the mentioned diptych using several methods such as FTIR spectroscopy, DSC thermal analysis and mass spectrometry. Experimental part FTIR spectra were registered with a JASCO 6100 spectrometer in the cm -1 spectral range with a resolution of 4 cm -1 using KBr pellet technique. Differential scanning calorimetry (DSC) was carried out by means of a Shimadzu DSC-60 calorimeter, the sample was heated in the range of C with a heating rate of 10 C/min in crimped aluminum sample cell. The purge gas was nitrogen purged of 60 ml/min. For data collection the Shimadzu TA-WS60 and TA software were employed. The Mass Spectra were obtained by Electron Impact at energy of 70 ev. The sample was introduced in mass spectrometer without any derivatization. The sample was heated until a vapor pressure of sample was enough for production of mass spectrum. Results and discussions Wood investigation FTIR analysis A detailed analysis of the FTIR spectra in different spectral domains is presented. The vibrational modes of the specific wood components (lignin, cellulose, hemicelluloses and carbohydrates) are identified in the FTIR spectra recorded in cm -1 spectral range, as can be observed in the figure 2 and table 1. The wood components (lignin, carbohydrates, cellulose, and hemicellulose) are identified as compared to literature data [24, 25]. A systemathic assignment of the specific bands of different wood components, based on literature data [26-29] is presented in table 1. The 8228 icon does not contains its wood essence in the corresponding catalogue. Based on comparative FTIR analysis (fig. 2) one can assume lime as wood essence. One can observe also that the rear side of the diptych is more deteriorated that the front part, the lignin and carbohydrates content being appreciably diminished. The absorption band at~1643 cm -1 is more intense in the spectrum of IcP (inner side) than in the MDP (outer side) icon spectrum. So, the quantity of the adsorbed water is higher for IcP wood as compared to the MDP wood. It is also possible, that the crystallinity degree of the wood [30] is quite different (being lower) for these two icons wood samples, MDP and IcP (table 2) and lower also that of a recent lime wood. The crystallinity index (Cr.I. or T.C.I.) defined elsewhere [25] as the ratios of different IR absorption bands, is reported for these wood samples in the table 2. If one compares the lignin/cellulose (L/C) ratio (L/C being defined also elsewhere [21]) by taking into account different analytical FTIR bands can be noticed (table 3) a lower L/C ratio for the actual (new) lime wood as compared to those of the historical samples. L/C ratio diminishes in time, so it is quite possible that the cellulose content can be diminished in time, being less stable that the lignin content. If one compares the FTIR spectra of the wooden supports with the oxalate sodium salt spectrum, (fig. 3) one can notice that some vibrational bands of the oxalate ion can Fig. 2 FTIR spectra of the 8228 icon support wood and of lime wood, cm -1 spectral domain Table 1 CHARACTERISTIC BANDS OF THE FTIR SPECTRA OF THE ICON LIME WOOD REV. CHIM. (Bucharest) 64 No

3 Table 2 CRYSTALLINITY DEGREE OBTAINED BY DIFFERENT METHODS Table 3 LIGNIN/CELLULOSE (L/C) RATIOS FOR NEW LIME WOOD, FOR INNER AND EXTERNAL ICON SIDES Fig. 3 FTIR spectra ( cm -1 spectral region) of: new lime wood (dash-dot-dot), of the sodium oxalate salt (dash), of the MDP and of IcP wooden supports (line and dash-dot, respectively) be identified in the wooden supports spectra also, especially for the back side (IcP wood) of the diptych. DSC analysis Wood is a polymeric material consisting of two major chemical components: lignin (18 35%) and carbohydrate (cellulose and hemicellulose) (65 75%). The characteristics of wood depend on its moisture content, age and conservation status. Because of its complex structure and interaction of components in wood, it is difficult to distinguish the decomposition processes corresponding to each component [31]. Investigating thermal decomposition of wood [32], cellulose has been by far the most frequently studied component which shows two exotherms at around 350 and at 510 C, respectively [33, 34]. Most of the literature reviewed on the thermal properties of lignin proposed that lignin decomposition begins at ~ 280 C, the maximum rate occurring between 350 and 450 C and the completion of the reaction occurs between 450 and 500 C [33, 35]. The characteristic temperatures increase with the ageing period and decrease with the material degrading [31]. Microorganism also contribute to degradation of the wood over time, the secretion of oxalic acid and the biomineralization process is strongly favored by fungi that act as calcification nuclei. At the final stage of fungal colonization, crystals of calcium salts appear in the surroundings of decayed wood fibers, the transformation of calcium oxalate into carbonate takes place between 400 and 550 C (peak temperature at 490 C) [36, 37]. By comparing the data resulted from DSC measurements of the wood sample: dried intact lime wood and of the old icon wooden support (fig. 4), one can see two exothermic peaks similar in value, but the wooden icon support presents an extra endothermic narrow signal having the maximum at 490 o C. First two peaks are characteristic to lime wood. The sharp peak located at 490 o C, is probably due to the presence of oxalates as a result of the fungal attack on the icon lime wooden support. Painting materials investigation FTIR Spectroscopy The FTIR characteristic frequencies of gypsum (fig.5) are identified at 3543 and 3403 cm -1 being the stretching vibrations of OH group specific to water molecules present in gypsum. In the cm -1 spectral domain the characteristic vibrations of the CH 2 - group are identified, probably assigned to the cholesterol. In the medium infrared range (fig. 5) the frequencies typically for CN vibration (2092 cm -1 ), for esters (1741 cm -1 ) and also for the degradation products of the egg yolk (1684 cm -1, oxo-cholesterol) are identified. Then, one can identify the specific frequencies of the C=O group (1629 cm -1 ), of proteins (1556 cm -1 ), of carbonates in small quantities (1405 and 870 cm -1 ), of sulfates ( cm -1 and cm -1 ) and of silicates ( and 468 cm -1 ). In the cm -1 spectral domain one can identify the calcium sulfate type, with or without one water molecule [38]. Based on this spectral identification, the proposed pigments are: -green: egg yolk+ultramarine+vermillon; -open blue: ultramarine; -red: lead minium; -dark blue: ultramarine+ Prussian blue EI-MS In the mass spectrum obtained from varnish of the icon 8228 several molecular ions can by seen: M 1 = 386, M 2 = 400 and M 3 = 414, (fig. 6) The peak at m/z 386 is the molecular ion of the cholesterol, a common compound of the egg yolk. The M 2 peak is attributed to the 7-oxo cholesterol, a compound resulted from cholesterol by an oxidation reaction along of the years and the molecular ion M 3 is attributed to Cholesteryl ethyl ester, a compound derived from cholesterol in presence of ethyl alcohol (used in the picture activities as fluidiser material). The compounds of Fig. 4 The thermograms of the lime wood and of the icon wooden support of Virgin Mary with Jesus child icon. 526

4 Fig. 5 FTIR spectra of the painting materials, cm -1 spectral domain. Fig. 6 EI Mass Spectrum obtained on a sample collected from 8228 diptych icon sterol ethers type were reported also as very useful biological markers in sediments [39]. The mass spectra obtained on samples collected from diptych Icon (8228) lead to conclusion that material contains egg yolk. Conclusions Wood analysis Lime wood has been identified as the wood diptych support of this icon and the rear part of this diptych could contain oxalate due to the back side fungal attack as FTIR spectroscopy and DSC method established. The crystallinity degree of the wooden supports is diminished in time whereas the lignin/cellulose ratio is increased. Painting materials analysis FTIR spectroscopy identifies gypsum as the painting ground. The used inorganic pigments were: ultramarine and Prussian blue for blue, lead minium for red pigment and vermillon for green one. Egg yolk as organic component and used as binder was identified. All identified molecular compounds of varnish, based on EI-MS data lead to the same conclusion that the egg yolk material was used in painting process. Acknowledgments: Financial support of the PN II 92095/2008 project is greatly acknowledged. References 1. PAPAIOANNOU, K., La peinture Byzantine et Russe, Rencontres, Paris, SOCOLOVA, M.N., Trud Ikonopista Sviato-Troitskaia Serghieva Lavra, ROUSSEAU, D.L icone, splendeur de son visage, Editions Sain-Paul, 6 rue Cassette , Paris, USPENSKY, L., Theologie de l Icone das l Eglise orthodoxe, Cerf, Paris, USPENSKY, L., LOSSKY, V., The Meaning of Icons, St. Vladimir s Seminary Press,New York, BACIU, A., MOLDOVAN, Z., BRATU, I., MARUTOIU, O.F., KACSÓ, I., GLAJAR, I., HERNANZ, A., MARUTOIU, C., Curr. Anal. Chem., 6, no. 1, 2010, p VÂRTACIU, R., Centers of Romanian Peinture from Banat, XIX-th Century, Ed.Eurobit, (in Romanian), Timiºoara, PORUMB, M., Dictionary of old paintings in Transylvania XIII-XVIII Century, Romanian Academy Publishing, (in Romanian), Bucharest, EFREMOV, AL., Romanian Icons, Ed.Meridiane, (in Romanian), Bucharest, SANDU, I.C.A., ROQUE, A.C.A., MATTEINI, P., SCHAFER, S., AGATI, G., CORREIA, C.R.,VIANA J.F.F.P., Microscopy Research and Technique, 75, 3, 2012, p SANDU, I.C.A., BRACCI, S., SANDU, I., LOBEFARO, M., Microscopy Research and Technique, 72, 10, 2009, p HÃRDÃLÃU, G.M., APVLVM XIX, 1981, p NICOLAUS, K., Manuel de Restauration des Tableaux. Ed. Kõnemann, Kõln, SANDU, I.C.A., LUCA, C., SANDU, I., Rev. Chim. (Bucharest), 51, no.7, 2000, p SANDU, I., LUCA, C., SANDU, I.C.A., CIOCAN, A., SULITEANU, N., Rev. Chim. (Bucharest), 52, no.9, 2001, p STUART, B., Analytical Techniques in Materials Conservation, John Wiley & Sons Ltd Barbara Stuart, Chichester, West Sussex, HERNANZ, A., BRATU, I., MARUTOIU, O.F., MARUTOIU, C., GAVIRA- VALLEJO, J.M., EDWARDS, H.C.M., Anal. Bioanal. Chem., 392, no.1-2, 2008, p EMANDI, I., IOVEA, M., DULIU, O.G., EMANDI, A., Int. J. Conserv. Sci., 2, no. 3, 2011, p MARUTOIU, C., BRATU, I., TRIFA, A., BOTIS, M., MARUTOIU, V.C, Int. J. Conserv. Sci., 2, no. 1, 2011, p HAHN, O., Analytical techniques in art, archaeology and conservation science, Springer Verlag, Berlin, SANDU, I.C.A.,VASILACHE, V., SANDU, I., LUCA, C., HAYASHI, M., Rev. Chim. (Bucharest), 59, no. 8, 2008, p SANDU, I.C.A., LUCA, C., SANDU, I., VASILACHE, V., HAYASHI, M., Rev. Chim. (Bucharest), 59, no. 4, 2008, p SANDU, I., LUCA, C., SANDU, I.C.A., VASILACHE, V., Rev.Chim., (Bucharest), 58, no. 10, 2007, p FAIX, O., Microchim. Acta, 94, no.1, 1988, p POPESCU, C.M., POPESCU, M.C., VASILE, C., Int. J. Biol. Macromol., 48, no. 4, 2011, p LUCA, C., SANDU, I.C.A., Rev. Chim. (Bucharest), 49, no. 9, 1998, p SANDU, I.C.A., LUCA, C., SANDU, I., POHONTU, M., Rev. Chim. (Bucharest), 52, no.7-8, 2001, p COLOM, X., CARILLO, F., NOGUÉS, F., GARRIGA, P., Polym. Deg. and Stab., 80, no. 3, 2003, p POPESCU, C.M., SAKATA, Y., POPESCU, M.C., OSAKA, A., VASILE, C., e-ps, 2, 2005, p POPESCU, C.M., LARSSON, P.T., OLARU, N., VASILE, C., Carbohyd. Polym., 88, no.2, 2012, p SANDU, I.C.A., BREBU, M., LUCA, C., SANDU, I., VASILE, C., Polym. Deg. and Stab., 80, no. 1, 2003, p.83. REV. CHIM. (Bucharest) 64 No

5 32. SANDU, I.C.A., LUCA, C., SANDU, I., ATYIM, P., Rev. Chim. (Bucharest) 52, no.1-2, 2001, p REH, U., KRAEPELIN, G., LAMPRECHT, I., Appl. Environ. Microb., 52, no. 5, 1986, p MARCOVICH, N.E., REBOREDO, M.M., ARANGUREN, M.I., Termochim. Acta, 372,no. 1-2, 2001, p SANDU, I.C.A., LUCA, C., SANDU, I., VASILACHE, V., SANDU, I.G., Rev. Chim. (Bucharest), 53, no. 9, 2002, p GENESTAR, C., PONS, C., Microchim. Acta, 162, no. 3-4, 2008, p CHAIYO, N., MUANGHLUA, R., NIEMCHAROEN, S., BOONCHOM, B.,SEEHARAJ, P., VITTAYAKORN, N., J. Therm. Anal. Calorim., 107, no. 3, 2012, p MOENKE, H., Mineralspektren, Acad. Verlag, Berlin, JOHNS, R.B., Biological Markers in the sedimentary Record, Elsevier Science Publishers B.V., Amsterdam, Manuscript received: