C

Pm

DEa

b

c

a

ARAA

KPMOG

1

aaMist

MraIlrtwimv

((

1d

Journal of Cultural Heritage 13 (2012) 107–113

ase study

igment identification in a Greek icon by optical microscopy and infraredicrospectroscopy

imitra Kovala-Demertzia,∗, Leuteris Papathanasisa, Rocco Mazzeob, Mavroudis A. Demertzisa,vagelia A. Varellac, Silvia Pratib

Department of Chemistry, University of Ioannina, 45110 Ioannina, GreeceUniversita’ di Bologna, sede di Ravenna, Via Tombesi dall’Ova 55, 48100 Bologna, ItalyDepartment of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece

r t i c l e i n f o

rticle history:eceived 4 January 2011ccepted 8 June 2011vailable online 23 August 2011

a b s t r a c t

Optical microscopy, cross-section and fragment Micro-FTIR spectroscopic techniques along with micro-chemical tests were used for the identification of pigments in two different samples of an icon.Representing the Last Judgement, and painted by the Greek master Ioannis from the village of Kapesovo

eywords:igments identificationicro-infrared spectroscopyptical microscopyreek icon

in the year 1771, the kneeling desk icon under investigation is a noteworthy contribution to the study ofmaterials in post-Byzantine visual arts. The main components found in the ground layer of both sampleswere gypsum, beeswax and a proteinaceous material. Cinnabar, Prussian blue and cerussite were identi-fied on the paint layers. The binding medium on the paint layers was weddelite. The materials used in thepainting and ground layers were characterized in order to clarify the painting technique. Proteinaceousmaterials have been identified as binders for the pigments, indicating a tempera painting technique.

. Introduction and aims of the research

At times neglected and often misinterpreted, post-Byzantinert denotes an interesting attempt to adopt Occidental featuresnd methodologies, while remaining faithful to the venerableedieval prototypes. Highly skilled professionals, with a surpris-

ngly updated knowledge, and an intense mobility potential, areeeking their identity experimenting with novel materials andechniques, without ever abandoning the great past.

The icon under consideration was donated to the Byzantineuseum of Ioannina, Greece, as part of a collection belonging to the

enowned Zosimaia academy. It is representing the Last Judgementnd was created as a kneeling-desk element in the year 1771 byoannis the painter (zographos), member of a distinguished artists’ine established in Kapesovo, a village in the then autonomousegion of Zagori, Epirus. The unambiguous provenance is combinedo a fascinating chromatic conception in red and blue, enrichedith golden shades. Thus, pigment analysis turns into a challeng-

ng scientific and aesthetic question, as it is amply evaluating theultilevel significance of the masterpiece; and subsequently pro-

iding a greater understanding on 18th century icon painting, and

∗ Corresponding author. Tel.: +30 26 50 08 42 5.E-mail addresses: dkovala@cc.uoi.gr (D. Kovala-Demertzi), me00280@cc.uoi.gr

L. Papathanasis), rocco.mazzeo@unibo.it (R. Mazzeo), mdemert@cc.uoi.grM.A. Demertzis), varella@chem.auth.gr (E.A. Varella).

296-2074/$ – see front matter © 2011 Elsevier Masson SAS. All rights reserved.oi:10.1016/j.culher.2011.06.003

© 2011 Elsevier Masson SAS. All rights reserved.

post-Byzantine visual arts on the whole. In Orthodox iconogra-phy, colours bear universally accepted theological connotations;permitting thus hue and brilliance to unequivocally comment thescenes and persons depicted [1]. Being an instant of supreme joyand ultimate sorrow, the Last Judgement is typically expressed bymeans of the most pure and vivid tones. Thus, saturated scarlet redand pure gold are adorning the faithful in royal splendour, whilealluding to the fire-faced Cherubs surrounding Christ, and to the FireRiver emerging from His feet.

The venerated egg tempera technique is actually the sole able tomeet all aesthetic and transcendental requirements of icon paint-ing on wood. Widely available in Orthodox countries, gypsum isthe traditional material employed for ground preparations, whilebeeswax, occasionally combined with low-cost inert flour or starch,is praised as a valuable and most ancient natural protective coating[2].

Joining in the same palette, natural cinnabar and imported syn-thetic Prussian blue should be considered a typical response forOrthodox painters during the late Ottoman centuries, since theseexperienced itinerant professionals were well aware of Modern artand science, and shared quite often the difficult task of reconcilingtradition and novel knowledge.

2. Experimental

The analytical procedure encompassed optical microscopy,micro-FTIR spectroscopy (ATR single measurements, mapping and

108 D. Kovala-Demertzi et al. / Journal of Cultural Heritage 13 (2012) 107–113

a and

Tm

cDcs1bsofl

wdsas

TR

Fig. 1. (a) Christ-Judge post-Byzantine icon in egg temper

ransmission mode with microdiamond compression cell) andicrochemical tests.An optical microscope Olympus BX51 M was used, and photomi-

rographs were recorded with a scanner digital camera OlympusP70. Samples were embedded in a polyester resin support, thenross-sectioned and polished with conventional methods usingilicon carbide card with successive grid from 120, 400, 800, to000. Dark field observation of the cross-sectioned samples haseen performed, and reflected light microscopy was utilized totudy the structure of the cross-sections under visible and ultravi-let light. Sample cross-sections were excited at 313 nm, while theuorescence emission was acquired in the whole visible spectrum.

A Thermo-Nicolet Avatar 370 spectrometer was used combinedith a Thermo Continuum IR microscope, fitted with a MCT type A

etector cooled by liquid nitrogen. Micro-FTIR analyses of the paintamples were performed by placing fragments of the paint samplesnd the cross-sectioned samples on the microscope motorizedtage and selecting the area through a 15 × Thermo-Electron

able 1esults of the studies in Optical Microscopy.

Sample OM stratigraphy Thickness �m CommentsVis

CJB (0) Ground, brownish-yellow 500 Several preparatio

CJB (1) Paint, blue 35 Dark blue particles5–20 �m) mixed wpigment particles

CJB (2) Surface, transparent layer 12 Layer barely seen

CJR (0) Ground, brownish- yellow Between the grounparticles are visiblepreliminary drawin

CJR (1) Paint, red-orange 68 Presence of darker

CJR (2) Surface, dark red 10 Layer not present i

(b) the same icon showing the paint samples CJB and CJR.

Infinity Reflachromat objective. Spectra were acquired in therange of 4000–650 cm−1. For ATR measurements, a micro slide-onATR with a silicon crystal was connected to the objective. ATRmapping was performed on selected area with a total of 35 (CJB)spectra collected with a step size of 20 microns. For transmittancemeasurements microdiamond compression cell was used.

In accordance to the historical and documentary research, twopaint samples (Christ Judge Blue [CJB], and Christ Judge Red [CJR])were collected from the icon, Fig. 1a red (CJR) and Fig. 1b blue (CJB)paint samples were taken, as illustrated in Fig. 1. Microchemicalanalytical tests have been used to identify the nature of pigments.

3. Results and discussion

3.1. Optical Microscopy

Both samples are characterized by a brownish-yellowground, consisting of several preparation layers with yellowish

UV

n layers Yellowish fluorescence, more evident betweenthe different layers

(irregular shape and sizeith finely ground white

Blue particles show no fluorescence, slightlyfluorescent matrix

Layer fluorescence white, a thin brown layer isalso visible near the surface (3)

d and the red layer black, probably traces ofg (indicated by arrows)

Yellowish fluorescence

crystals Where the layer is fractured, a light yellowfluorescence is visible probably caused by theinfiltration of a varnish layer (3)

n the entire section Dark pink fluorescence

D. Kovala-Demertzi et al. / Journal of Cultural Heritage 13 (2012) 107–113 109

F omicrr urface

flflauCwPpboi

TC

ig. 2. (a) and (b). Cross-sections of samples CJB and CJR respectively: optical photespectively): (0) ground layer, (1) paint layer, (2) surface layer and (3) outermost s

uorescence. On sample CJR, red orange crystals indicating yellowuorescence are visible, while the black particles present probablyllude to traces from a preparatory drawing, a practice commonlysed in post-Byzantine icon painting. On the paint layer of sampleJB, the irregular dark blue particles measure 5–20 �m, are mixedith a finely ground white pigment, and indicate no fluorescence.

hotomicrographs are displaying a dark red surface layer bearingink fluorescence for sample CJR, and a transparent surface layer

earing white fluorescence for sample CJB. The light yellow flu-rescence at CJR layer fragmentations is probably caused by thenfiltration of a varnish layer (Table 1, Fig. 2).

able 2haracteristic Infrared Bands on the sample Christ Judge Red (CJR) in cm−1.

Sample Materials Ch

CJRCJR-ground Gypsum 11

Beeswax 29Protein 16

CJR-layer Binding medium 33Impurities 11

CJR-Dark red layer Binding medium 33Red lake 32Weddellite 16Deposits 11

ograph under visible and UV fluorescence (200 × and 500 × original magnification.

3.2. Micro-FTIR Spectroscopy

Cross-section and fragment micro-FTIR spectroscopic analyseswere performed on different layers of the two samples CJB and CJR.ATR measurements were performed stratigraphically on differentpoints of the ground layer, Tables 2 and 3. The ground materi-als and the binding medium in the preparation layer proved tohave the same composition in both samples, Fig. 3. The prepara-

tion layer was composed of gypsum (3540, 3402, 1682, 1620, 1148,1100, 672 cm−1) [3], and beeswax (2955, 2918, 2849, 1736, 1462,1463, 1379, 730, 720 cm−1), with further traces of proteinaceous

aracteristic Infrared Bands in cm−1

47, 1100, 67252, 2917, 2849, 1737, 1473, 1460, 1377, 72955, 154304, 2953, 2916, 2848, 1730,1642, 1531, 1457, 1407, 1380, 1318, 72366, 1113, 1068, 786

40, 2953, 2919, 2850, 1652, 1549, 1535, 1463, 1453, 1379, 1260, 1243, 1162, 72086, 2919, 2850, 1652, 1567, 1473, 1411, 1080, 898, 85250132111, 1061, 1035, 781

110 D. Kovala-Demertzi et al. / Journal of Cultural Heritage 13 (2012) 107–113

Table 3Characteristic Infrared Bands on the sample Christ Judge Blue (CJB) in cm−1.

Sample Materials Characteristic Infrared Bands in cm−1

CJBCJB-ground Gypsum 3540, 3402, 1682, 1620, 1148, 1100, 672

Beeswax 2955, 2917, 2849, 1736, 1472, 1463, 1379, 730Protein 1658, 1547

CJB-layer Gypsum 1148, 1100, 673Beeswax 2955, 2918, 2849, 1462, 1737, 729, 719Prussian Blue 2087Cerussite 1412, 837, 676Binding Medium 3387, 2955, 2918, 2849, 1737, 1643, 1548Whewellite 1324

CJB-surface Varnish 2918, 2850, 1707, 1447, 1378, 1227, 1160, 1116, 1039, 959Oil 2918, 2850, 1731, 1447, 1378, 1160, 720

168333

mtb1bsa1

FG

WeddelliteCerussiteBinding medium

aterial [4]. The presence of gypsum, CaSO4.2H2O, is indicated byhe appearance of stretching bands v(OH) at 3540 and 3402 cm−1,ending vibrations at 1682 and 1620 cm−1, and two bands at110 and 672 cm−1, assignable respectively to the stretching and

ending modes of sulphate anions [3]. Occurrence of beeswax isuggested by the stretching bands v(CH2) and v(CH3) at 2955, 2918,nd 2849 cm−1 and the bending vibrations �(CH2) and �(CH3) at472 and 1463 cm−1; the shoulder at 1736 cm−1 corresponds to the

ig. 3. �-FT-IR spectra by ATR mode on the ground layer of the (a) CJB and (b) CJR. Designto gypsum.

48, 13187, 67640, 2918, 2850, 1648, 1553

C–O stretching band of the ester function. All these data are consis-tent with the presence of a waxy substance. The doublet at 730 and720 cm−1 is attributed to beeswax. Proteinaceous materials haverelevant peaks at 1658 and 1547 cm−1 [4].

The red pigment cannot be identified, since possible compoundsabsorb outside the detector range, thus the red layer spectrum isshowing sole the absorbance of the organic materials, e.g. egg tem-pera, bearing characteristic amide bands at 1643 and 1548 cm−1.

ated as B bands corresponding to Beeswax, as P to proteinaceous materials and as

D. Kovala-Demertzi et al. / Journal of Cultural Heritage 13 (2012) 107–113 111

F er ana

Scatad(TmaT

lF21cmawocitci

ig. 4. �-FT-IR spectra, mATR on cross-section, on the CJR paint layer (a) CJR-Red Lays B to beeswax, as W to whewellite, as L to red lake and as I to impurities.

ince relevant microchemical tests proved the pigment to beinnabar, the broad band in the 1200–1000 cm−1 region can bettributed to sulphate impurities in it, implying the presence ofhe natural mineral rather than vermillion. The dark red particlesre characterized by the absorptions of the binding medium, wed-ellite Ca(COO)2.5H2O, and some deposition material; a red lakeglaze) has been also identified in low concentration, Fig. 4, Table 2.he layer of glaze (Table 2, Fig. 4b) seems to contain proteinaceousaterial, most probably oxidized egg. This type of result needs

dditional information in order to interpret the data with surety.his probably was an egg tempera glaze.

As indicated in Fig. 5, ATR measurements of the paintayer on sample CJB suggest the presence of Prussian blue,e4[Fe(CN)6]3.nH2O, since the cyanide stretching vibration at087 cm−1 is highly specific for this pigment [5]. The bands at412, 837 and 676 cm−1 are associated to mineral lead carbonateerussite, PbCO3 [6]. The ATR spectrum yields no unequivocal infor-ation for the binding medium, the ester group (1737 cm−1) being

ttributable to egg yolk, as well as to beeswax contaminations,ith further bands at 730, 720 cm−1. Several dark blue particles

f the layer were analyzed in transmission mode, and the resultsonfirmed the presence of Prussian blue, cerussite and the bind-

ng medium; the ester shoulder at 1740 cm−1 is clearly assignableo egg tempera [7,8], while the absence of beeswax is definitelyonfining it to the ground layer. A layer of oil varnish is displacedn Fig. 5b, Table 3. The absorption peak in the surface coating is

d (b) CJR-Dark Red Layer. Designated as M bands corresponding to binding medium,

the carboxylic acid stretching band at 1707 cm−1 characteristic ofthe natural resins [9]. The spectral profile of the varnish is similar tothe natural triterpenoids resins dammar or mastic, the former beingintroduced into the market only in 1829 [9,10]. These two resins aretoo similar to be distinguished by infrared spectroscopy. These tworesins exhibit a multiple absorption in the region 1250–1000 cm−1,as well as at 1380 and a strong absorption at 1030 cm−1 [9,10].

The results are confirmed by the ultraviolet light microscopicobservation on a red and blue fragment, Fig. 6. The map wasrecorded on a representative area of the sample (80 × 120 �m)for a better definition of the component localization. In particu-lar, mapping permitted to confine the presence of beeswax to theground layer, and confirmed the use of egg tempera in the paintlayer.

3.3. Microchemical tests

A microchemical test was carried out to elucidate the natureof the binding medium. When adding a drop of NaOH 10% toa fragment of the CJR sample, the outer dark red layer imme-diately starts to dissolve, due to saponification of the organicmaterial present. This behaviour is characteristic for fatty acid

compounds–e.g. oils–or organic acids, including colorants. Con-firming the UV fluorescence, it is strongly suggesting that a redlake may have been used for glazing purposes. The red layer seemsunaffected, and partial desegregation occurs only when shifting

112 D. Kovala-Demertzi et al. / Journal of Cultural Heritage 13 (2012) 107–113

Fig. 5. �-FT-IR spectra on the CJB paint layer: (a) mATR on cross-section and (b) mATR on surface. Designated as M bands corresponding to binding medium, as C to cerussite,as PB to Prussian Blue and as W to whewellite.

Fig. 6. (a) CJB cross section photomicrograph (original magnification 200 ×) with the indication of the area selected for the ATR mapping. Chemigram mapping of (b) Prussianblue (2087 cm−1), (c) gypsum (672 cm−1), (d) beeswax (729 cm−1) and (e) egg tempera (1737, 1643, 1548 cm−1). Red and blue colours indicate areas of respectively higherand lower concentration.

of Cul

tdit

rfoalo

3

mocsOaoeasbristivmgbii

D. Kovala-Demertzi et al. / Journal

he sample with a glass rod. A similar, although less apparent,esegregation of the blue layer is observed in sample CJB, affirm-

ng the FTIR analysis conclusion that the technique used was eggempera.

Identification of cinnabar as the red pigment is based in theeactions: HgS + HNO3 → Hg2+ + H2S(g), Hg2+ + KI → HgI42−. A smallragment of the sample is placed on a glass slide; under the stere-microscope several crystals of KI and 1–2 drops of HNO3 in 1%queous solution are added. The red colour gradually fades awayeaving a slightly yellow solution, bearing the characteristic H2Sdour.

.4. Conclusions

The kneeling desk icon under investigation, the Last Judge-ent, was painted by the Greek master Ioannis from the village

f Kapesovo in the year 1771. Joining in the same palette naturalinnabar and imported synthetic Prussian blue should be con-idered a typical response for Orthodox painters during the latettoman centuries, since these experienced itinerant profession-ls were well aware of Modern art and science, and shared quiteften the difficult task of reconciling tradition and novel knowl-dge. For Ioannis and his numerous colleagues, natural cinnabar isn ancient colorant worth using for its smooth application, provedtability, and high aesthetic value. At the same time, Prussianlue constitutes an appealing option for those wishing a satu-ated radiant hue at a moderate cost. Since the chromatic results the same, there is no reason to insist in favouring the expen-ive natural ultramarine proposed in the earlier tradition. Faithfulo millenary concepts, Orthodox iconography is always ready tontroduce improved methodologies and innovative materials, pro-ided that the overall theological approach is not betrayed. Theain components found in the ground layer of both samples were

ypsum, beeswax and a proteinaceous material. Cinnabar, Prussianlue and cerussite were identified on the paint layers. The bind-

ng medium on the paint layers was weddelite. The materials usedn the painting and ground layers were characterized in order to

[

[

tural Heritage 13 (2012) 107–113 113

clarify the painting technique. Proteinaceous materials have beenidentified as binders for the pigments, indicating a tempera paint-ing technique. Since, there is not an extensive body of literatureconcerning the technique of construction of Greek icons in gen-eral [11], the present project together with art historical researchcould provide a greater understanding about the icon painting tech-nique and contribute to the general body of knowledge concerningon 18th century icons. This examination contributes to the bodyof knowledge concerning technical information, and will be of usewhen put in context with existing and future studies on the subject.

References

[1] E.A. Varella, Tetrachromy, in: M. Papanikolaou, J. Bowlt (Eds.), Behind the BlackSquare, State Museum for Contemporary Art, Thessaloniki, 2003, pp. 211–225.

[2] M. Regert, J. Langlois, E. Laval, A.-S. Le Ho. , S. Pages Camagna, Elucidationof molecular and elementary composition of organic and inorganic sub-stances involved in 19th century wax sculptures using an integrated analyticalapproach, Anal. Chim. Acta 577 (1) (2006) 140–152.

[3] P.K. Mandal, T.K. Mandal, Anion water in gypsum (CaSO4 center dot 2H(2)O)and hemihydrate (CaSO4 center dot 1/2H(2)O), Cement Concrete Res. 32 (2)(2002) 313–316.

[4] M. Odlyha, Investigation of the binding media of paintings by thermoanalyticaland spectroscopic techniques, Thermochim. Acta 269 (1995) 705–727.

[5] M. Ortega Aviles, P. Vandenabeele, D. Tenorio, G. Murillo, M. Jimenez Reyes, N.Gutierrez, Spectroscopic investigation of a ‘Virgin of Sorrows’ canvas painting:a multi-method approach, Anal. Chim. Acta 550 (1–2) (2005) 164–172.

[6] R. Mazzeo, S. Prati, M. Quaranta, E. Joseph, E. Kendix, M. Galeotti, Attenuatedtotal reflection micro FTIR characterisation of pigment–binder interaction inreconstructed paint films, Anal. Bioanal. Chem. 392 (2008) 65–76.

[7] D. Ajò, U. Casellato, E. Fiorin, P.A. Vigato, Ciro Ferri’s frescoes: a study of paintingmaterials and technique by SEM-EDS microscopy, X-ray diffraction, micro FT-IRand photoluminescence spectroscopy, J. Cult. Herit. 5/4 (2004) 333–348.

[8] S. Bianchin, U. Casellato, M. Favaro, P.A. Vigato, Painting technique and state ofconservation of wall paintings at Qusayr Amra, Amman-Jordan, J. Cult. Herit.8/3 (2007) 289–293.

[9] O. Katsibiri, R.F. Howe, Characterisation of the transparent surface coatings onpost-Byzantine icons using microscopic, mass spectrometric and spectroscopictechniques, Microchem. J. 94 (2010) 14–23.

10] S. Prati, G. Sciutto, R. Mazzeo, C. Torri, D. Fabbri, Application of ATR-far-infraredspectroscopy to the analysis of natural resins, Anal. Bioanal. Chem. 399 (2011)3081–3091.

11] L. Burgio, R.J.H. Clark, K. Theodoraki, Raman microscopy of Greek icons: iden-tification of unusual pigments, Spectrochim. Acta Part A 59 (2003) 2371–2389.