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The combined use of lead–tin yellow type I and II on a canvas painting by Pietro Perugino
Journal of Cultural Heritage 8 (2007) 65e68 http://france.elsevier.com/direct/CULHER/
Case study
The combined use of leadetin yellow type I and II on a canvas painting by Pietro Perugino Ilaria Borgia a, Brunetto Giovanni Brunetti a, Costanza Miliani b,*, Camilla Ricci a, Claudio Seccaroni c, Antonio Sgamellotti a,b a
INSTM and Centre SMAArt, Department of Chemistry, University of Perugia, via Elce di sotto 8, 06123 Perugia, Italy b CNR-ISTM (Institute of Molecular Science and Technologies), c/o Department of Chemistry, University of Perugia, via Elce di sotto 8, 06123 Perugia, Italy c ENEA, Unita` Tecnico Scientifica per i Materiali e le Nuove Tecnologie, C.R. Casaccia, s.p. Anguillarese, 301, 00060 Santa Maria di Galeria, Rome, Italy Received 20 October 2006; accepted 26 October 2006
Abstract This article reports the first occurrence of the combined use of lead and tin yellow type I and type II identified on the same paint layer. The two forms have been identified by Raman microscopy on a green layer from the background of the painting Gonfalone della Giustizia (confraternity of Justice banner) executed at Perugia around 1496 by Pietro Perugino. Ó 2007 Published by Elsevier Masson SAS. Keywords: Leadetin yellow; Raman; Perugino; Pigments; XRF
1. Research aim The history of use of leadetin yellow is complex due to the existence of two forms, namely type I and type II, that where first differentiated by Ku¨hn only around the 1970 [1]. Type I is lead stannate, Pb2SnO4, whose structure has been determined by X-ray diffraction, neutron diffraction and vibrational spectroscopy, is composed by chains of edge-sharing Pb(IV)O6 octahedra linked laterally by Sn(IV) and Pb(II) atoms, each one with pyramidal arrangement of three oxygen neighbours [1]. It is believed that leadetin yellow I corresponds to the giallolino fino mentioned by Merrifield [2], and probably first used in the Flanders. The less studied type II is a lead tin oxide with a defect pyrochlore structure where silicon occupies some tin sites (PbSn1xSixO3) making the colour a deeper yellow. Clark et al. have recently resolved its crystal structure by * Corresponding author. Tel.: þ39 075 5855522; fax: þ39 075 5855606. E-mail address: [email protected] (C. Miliani). 1296-2074/$ - see front matter Ó 2007 Published by Elsevier Masson SAS. doi:10.1016/j.culher.2006.10.006
powder X-ray diffraction showing that Sn and Si atoms are randomly distributed over the same type of sites with a Sn/Si ratio z 3/1 (i.e. x z 0.25) [3]. The earlier recipe of leadetin yellow II was found by Merrifield in the so-called Bolognese manuscript of the first half of the 15th Century [2]. According to the manuscript, the pigment can be obtained by either pulverizing a lead glass containing tin or, alternatively, by doping preformed yellow type I with silicon (Pb2SnO4 þ SiO2 / PbSn1xSixO3, at T ¼ 800e950 C). From other studies on the leadetin yellow, type II results to have been diffused in Florence during the 14th Century, and in Venice and Bohemia during the 16th Century [4]. In Italy it was replaced by the type I during the second quarter of the 15th Century [1]. However, the identification of leadetin yellow type II on 16th and 17th Century paintings, specifically of Venetian artists, such as Tintoretto or Veronese, shows that the use and diffusion of the leadetin yellows is still not clear [1]. It seems that leadetin yellow type II did not completely fall in
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I. Borgia et al. / Journal of Cultural Heritage 8 (2007) 65e68
disuse, at least in Venice, where the glass production was an important economic activity since Middle Age. Leadetin yellows type I and II were never found in the same painting with the exception of three canvas painted by Veronese, also from the Venice area [5]. However, in all these cases the two yellow pigments were identified in different areas or different paint layers. This seems to indicate that they were probably intentionally used to obtain different hues or were from different batches of yellow pigments purchased for the painting. During a wide study on several paintings by Perugino, aimed to the characterisation of its whole palette through Raman microscopy, scanning electron microscopy and portable X-ray fluorescence [6,7], leadetin yellow type I and type II were identified in the same paint layer in the painting Gonfalone della Giustizia (confraternity of Justice) executed by Perugino around 1496 at Perugia and conserved at the Galleria Nazionale dell’Umbria (see Fig. 1). 2. Experimental section In situ X-ray fluorescence (XRF) measurements were carried out at the Galleria Nazionale dell’Umbria (Perugia) using
Fig. 2. XRF spectrum of the blue zone, in the insert the cps results are reported.
a portable equipment made with a miniaturized X-ray generator EIS P/N 9910, equipped with a tungsten anode and a silicon drift detector. Stratigraphical investigations on cross-section were performed using a scanning electron microscope with an energy dispersion X-ray spectrometer (SEM-EDS). MicroRaman spectra were collected on the cross-section using a JASCO Ventuno using 532 nm excitation from an Nd:YAG laser. In the experiment, the laser was focused on the crosssection through the 100 objective lens and the laser power at the sample was always kept below 2 mW to avoid the laser-induced degradation of yellow pigments. 3. Results and discussion Non-invasive XRF investigations of the painting allowed the elemental mapping of the upper layers. The blue robe of
Fig. 1. Image of the painting Gonfalone della Giustizia (confraternity of Justice banner), Galleria Nazionale dell’Umbria, Perugia.
Fig. 3. Detail of the sampled area.
I. Borgia et al. / Journal of Cultural Heritage 8 (2007) 65e68
67
Table 1 SEM-EDS elemental composition of paint layers of the cross-section from the men’s robe
Outer layer (blue) Inner layer (green)
Na
Al
Si
Pb
Cl
K
Sn
Ca
Fe
Cu
3.67 0.15
11.06 0.28
25.83 1.56
37.26 10.12
0.81 0.15
13.44 0.16
e 0.78
4.81 0.17
3.11 5.88
e 80.76
a man belonging to the confraternity was found to contain both lead and tin atoms, together with copper. Fig. 2 shows a typical spectrum with the tin peaks (Ka ¼ 25.3 keV and Kb ¼ 28.5 keV). A small sample of the blue dress was collected along an existing lacuna and mounted as cross-section (see the detail, in Fig. 3). Observations with an optical microscope revealed the presence of two overlapping paint layers: a green layer making up the landscape on the background covered by a blue layer making the men’s cloth. Table 1 reports the SEM-EDS elemental composition of the two layers. The lower green layer is 70e100 mm thick and is made up of a copperbased matrix containing crystals of both lead and tin and, in some case, silicon. The upper blue layer is about 50 mm thick, and is mainly made up of crystals containing Si, Al, Na, and K, and was easily identified as lapis lazuli through microRaman measurements. The copper-based matrix in the green layer showed a low Raman scattering and no bands referable to malachite or verdigris, thus suggesting the use of a copper resinate. Several lead tin based crystals showed two different types of Raman features. The first characterised by a strong band at 135 cm1, a medium band at 195 cm1 and two weak bands at 291 and 450 cm1; and the second characterised by a strong band at 145 cm1 and a broad scattering at about 325 cm1. Two examples of these different Raman
Fig. 4. Raman spectra collected on crystals of (a) leadetin yellow type I and (b) leadetin yellow type II (532 nm excitation, spectral resolution 2 cm1, 100 objective lens, power 1.1 and 0.6 mW, respectively).
features are compared in Fig. 4. The first spectrum is assignable to leadetin yellow type I even though the low frequency peak at 135 cm1 (assigned to a lattice PbeO mode) is slightly blue-shifted from those reported by Clark et al. [3]. The second spectrum is assignable to leadetin yellow type II again with a slightly blue-shifted PbeO lattice mode (145 cm1 instead of 138 cm1 [3]). A possible shift of the PbeO lattice mode has been already reported, as a function of firing temperature, for lead antimonate yellow, a synthetic pigment structurally related to leadetin yellow type II [8]. It is difficult to provide a reason or explanation for the presence of both lead and tin yellow type I and type II in the same green paint layer. An intentional mixture of the two separate forms seems unlikely with the only other published case found within a very peculiar geographical and chronological context: a work by British artist John Bettes, the portrait of Lady Spenser, datable 1590 and owned by a private collection [9]. Anyhow, it is worth noting that also in this case the two crystallographic forms were identified by Raman microscopy. The presence of leadetin yellow type I associated to leade tin yellow type II could be explained by a stoichiometric excess of type I compared to the silica or to improper firing. However, in this case, the type II would be the intentional pigment used by Perugino, a surprising case considering the history of use of this material. In fact, as mentioned above, in the Renaissance Italian paintings, the occurrence of type II is very rare and the few identified cases are confined to the Venice area. On the other hand, we believe that the known contacts between Perugino and the Gesuati convent in Florence, where pigments and glass were made, represent a too weak bound to directly explain the data presented in this paper. In fact, among Florentine painters of the period, leadetin yellow type II has been never detected. It is important to highlight that the advancement of technology has allowed this discovery and that it is likely not to remain a single case. Earlier systematic studies on the relative frequencies of leadetin yellow I and II on paintings were carried out with the aid of X-ray diffraction [1] or by SEMEDS and were based, as distinguishing factor, on the presence or the absence of silicon [5]. Undoubtedly, the recently available Raman microscopy, due to its high spatial resolution, sensibility and specificity, represents a far more powerful tool to identify and distinguish the two crystallographic types. Hopefully, more Raman microscopy or micro X-ray diffraction studies of leadetin yellow samples will be carried out both to determine other occurrences of the combined presence of leadetin yellow type I and II and to help explain the reason behind this combined use.
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I. Borgia et al. / Journal of Cultural Heritage 8 (2007) 65e68
References [1] H. Ku¨hn, Leadetin yellow, Studies in Conservation 13 (1968) 7e33 (Reprinted with revisions in: Artists’ Pigments, a Handbook of their History and Characteristics, vol. 2, National Gallery of Art, Washington, 1993). [2] M.P. Merrifield, Original Treatises on the Arts of Paintings, John Murray, London, 1849. [3] R.J.H. Clark, L. Cridland, B.M. Kariuki, K.D.M. Harris, R. Withnall, Synthesis, structural characterisation and Raman spectroscopy of the inorganic pigments lead tin yellow types I and II and lead antimonite yellow: their identification on medieval paintings and manuscripts, Journal of the Chemical Society, Dalton Transactions (1995) 2577e 2582. [4] E. Martin, A.R. Duval, Les deux varie´te´s de jaune de plomb et d’e´tain: e´tude chronologique, Studies in Conservation 35 (1990) 117e136.
[5] N. Penny, M. Spring, Veronese’s paintings in the national gallery, Technique and Materials: Part I. National Gallery Technical Bulletin 16 (1995) 5e29. [6] I. Borgia, B.G. Brunetti, P. Moioli, C. Seccaroni, A. Sgamellotti, Four anomalous pigments in Perugino’s palette: Statistics, context, hypotheses, in: The Painting Technique of Pietro Vannucci, called the Perugino, Workshop Proceedings, Perugia 13e14 April, Nardini Editore, Firenze, 2003, pp. 29e41. [7] C. Ricci, C. Miliani, I. Borgia, B.G. Brunetti, A. Sgamellotti, C. Seccaroni, P. Passalacqua, The Perugino’s palette: integration of an extended in situ XRF study with aimed Raman scattering measurements, Journal of Raman Spectroscopy 35 (2004) 616e621. [8] K. Sakellariou, C. Miliani, A. Morresi, M. Ombelli, Spectroscopic investigation of yellow majolica glazes, Journal of Raman Spectroscopy 35 (2004) 61e67. ¨ ber den in der Malerei verwendeten gelben Farbstoff der [9] R. Jacobi, U alten Meister, Angewandte Chemie 54 (1941) 28e29.
Case study
The combined use of leadetin yellow type I and II on a canvas painting by Pietro Perugino Ilaria Borgia a, Brunetto Giovanni Brunetti a, Costanza Miliani b,*, Camilla Ricci a, Claudio Seccaroni c, Antonio Sgamellotti a,b a
INSTM and Centre SMAArt, Department of Chemistry, University of Perugia, via Elce di sotto 8, 06123 Perugia, Italy b CNR-ISTM (Institute of Molecular Science and Technologies), c/o Department of Chemistry, University of Perugia, via Elce di sotto 8, 06123 Perugia, Italy c ENEA, Unita` Tecnico Scientifica per i Materiali e le Nuove Tecnologie, C.R. Casaccia, s.p. Anguillarese, 301, 00060 Santa Maria di Galeria, Rome, Italy Received 20 October 2006; accepted 26 October 2006
Abstract This article reports the first occurrence of the combined use of lead and tin yellow type I and type II identified on the same paint layer. The two forms have been identified by Raman microscopy on a green layer from the background of the painting Gonfalone della Giustizia (confraternity of Justice banner) executed at Perugia around 1496 by Pietro Perugino. Ó 2007 Published by Elsevier Masson SAS. Keywords: Leadetin yellow; Raman; Perugino; Pigments; XRF
1. Research aim The history of use of leadetin yellow is complex due to the existence of two forms, namely type I and type II, that where first differentiated by Ku¨hn only around the 1970 [1]. Type I is lead stannate, Pb2SnO4, whose structure has been determined by X-ray diffraction, neutron diffraction and vibrational spectroscopy, is composed by chains of edge-sharing Pb(IV)O6 octahedra linked laterally by Sn(IV) and Pb(II) atoms, each one with pyramidal arrangement of three oxygen neighbours [1]. It is believed that leadetin yellow I corresponds to the giallolino fino mentioned by Merrifield [2], and probably first used in the Flanders. The less studied type II is a lead tin oxide with a defect pyrochlore structure where silicon occupies some tin sites (PbSn1xSixO3) making the colour a deeper yellow. Clark et al. have recently resolved its crystal structure by * Corresponding author. Tel.: þ39 075 5855522; fax: þ39 075 5855606. E-mail address: [email protected] (C. Miliani). 1296-2074/$ - see front matter Ó 2007 Published by Elsevier Masson SAS. doi:10.1016/j.culher.2006.10.006
powder X-ray diffraction showing that Sn and Si atoms are randomly distributed over the same type of sites with a Sn/Si ratio z 3/1 (i.e. x z 0.25) [3]. The earlier recipe of leadetin yellow II was found by Merrifield in the so-called Bolognese manuscript of the first half of the 15th Century [2]. According to the manuscript, the pigment can be obtained by either pulverizing a lead glass containing tin or, alternatively, by doping preformed yellow type I with silicon (Pb2SnO4 þ SiO2 / PbSn1xSixO3, at T ¼ 800e950 C). From other studies on the leadetin yellow, type II results to have been diffused in Florence during the 14th Century, and in Venice and Bohemia during the 16th Century [4]. In Italy it was replaced by the type I during the second quarter of the 15th Century [1]. However, the identification of leadetin yellow type II on 16th and 17th Century paintings, specifically of Venetian artists, such as Tintoretto or Veronese, shows that the use and diffusion of the leadetin yellows is still not clear [1]. It seems that leadetin yellow type II did not completely fall in
66
I. Borgia et al. / Journal of Cultural Heritage 8 (2007) 65e68
disuse, at least in Venice, where the glass production was an important economic activity since Middle Age. Leadetin yellows type I and II were never found in the same painting with the exception of three canvas painted by Veronese, also from the Venice area [5]. However, in all these cases the two yellow pigments were identified in different areas or different paint layers. This seems to indicate that they were probably intentionally used to obtain different hues or were from different batches of yellow pigments purchased for the painting. During a wide study on several paintings by Perugino, aimed to the characterisation of its whole palette through Raman microscopy, scanning electron microscopy and portable X-ray fluorescence [6,7], leadetin yellow type I and type II were identified in the same paint layer in the painting Gonfalone della Giustizia (confraternity of Justice) executed by Perugino around 1496 at Perugia and conserved at the Galleria Nazionale dell’Umbria (see Fig. 1). 2. Experimental section In situ X-ray fluorescence (XRF) measurements were carried out at the Galleria Nazionale dell’Umbria (Perugia) using
Fig. 2. XRF spectrum of the blue zone, in the insert the cps results are reported.
a portable equipment made with a miniaturized X-ray generator EIS P/N 9910, equipped with a tungsten anode and a silicon drift detector. Stratigraphical investigations on cross-section were performed using a scanning electron microscope with an energy dispersion X-ray spectrometer (SEM-EDS). MicroRaman spectra were collected on the cross-section using a JASCO Ventuno using 532 nm excitation from an Nd:YAG laser. In the experiment, the laser was focused on the crosssection through the 100 objective lens and the laser power at the sample was always kept below 2 mW to avoid the laser-induced degradation of yellow pigments. 3. Results and discussion Non-invasive XRF investigations of the painting allowed the elemental mapping of the upper layers. The blue robe of
Fig. 1. Image of the painting Gonfalone della Giustizia (confraternity of Justice banner), Galleria Nazionale dell’Umbria, Perugia.
Fig. 3. Detail of the sampled area.
I. Borgia et al. / Journal of Cultural Heritage 8 (2007) 65e68
67
Table 1 SEM-EDS elemental composition of paint layers of the cross-section from the men’s robe
Outer layer (blue) Inner layer (green)
Na
Al
Si
Pb
Cl
K
Sn
Ca
Fe
Cu
3.67 0.15
11.06 0.28
25.83 1.56
37.26 10.12
0.81 0.15
13.44 0.16
e 0.78
4.81 0.17
3.11 5.88
e 80.76
a man belonging to the confraternity was found to contain both lead and tin atoms, together with copper. Fig. 2 shows a typical spectrum with the tin peaks (Ka ¼ 25.3 keV and Kb ¼ 28.5 keV). A small sample of the blue dress was collected along an existing lacuna and mounted as cross-section (see the detail, in Fig. 3). Observations with an optical microscope revealed the presence of two overlapping paint layers: a green layer making up the landscape on the background covered by a blue layer making the men’s cloth. Table 1 reports the SEM-EDS elemental composition of the two layers. The lower green layer is 70e100 mm thick and is made up of a copperbased matrix containing crystals of both lead and tin and, in some case, silicon. The upper blue layer is about 50 mm thick, and is mainly made up of crystals containing Si, Al, Na, and K, and was easily identified as lapis lazuli through microRaman measurements. The copper-based matrix in the green layer showed a low Raman scattering and no bands referable to malachite or verdigris, thus suggesting the use of a copper resinate. Several lead tin based crystals showed two different types of Raman features. The first characterised by a strong band at 135 cm1, a medium band at 195 cm1 and two weak bands at 291 and 450 cm1; and the second characterised by a strong band at 145 cm1 and a broad scattering at about 325 cm1. Two examples of these different Raman
Fig. 4. Raman spectra collected on crystals of (a) leadetin yellow type I and (b) leadetin yellow type II (532 nm excitation, spectral resolution 2 cm1, 100 objective lens, power 1.1 and 0.6 mW, respectively).
features are compared in Fig. 4. The first spectrum is assignable to leadetin yellow type I even though the low frequency peak at 135 cm1 (assigned to a lattice PbeO mode) is slightly blue-shifted from those reported by Clark et al. [3]. The second spectrum is assignable to leadetin yellow type II again with a slightly blue-shifted PbeO lattice mode (145 cm1 instead of 138 cm1 [3]). A possible shift of the PbeO lattice mode has been already reported, as a function of firing temperature, for lead antimonate yellow, a synthetic pigment structurally related to leadetin yellow type II [8]. It is difficult to provide a reason or explanation for the presence of both lead and tin yellow type I and type II in the same green paint layer. An intentional mixture of the two separate forms seems unlikely with the only other published case found within a very peculiar geographical and chronological context: a work by British artist John Bettes, the portrait of Lady Spenser, datable 1590 and owned by a private collection [9]. Anyhow, it is worth noting that also in this case the two crystallographic forms were identified by Raman microscopy. The presence of leadetin yellow type I associated to leade tin yellow type II could be explained by a stoichiometric excess of type I compared to the silica or to improper firing. However, in this case, the type II would be the intentional pigment used by Perugino, a surprising case considering the history of use of this material. In fact, as mentioned above, in the Renaissance Italian paintings, the occurrence of type II is very rare and the few identified cases are confined to the Venice area. On the other hand, we believe that the known contacts between Perugino and the Gesuati convent in Florence, where pigments and glass were made, represent a too weak bound to directly explain the data presented in this paper. In fact, among Florentine painters of the period, leadetin yellow type II has been never detected. It is important to highlight that the advancement of technology has allowed this discovery and that it is likely not to remain a single case. Earlier systematic studies on the relative frequencies of leadetin yellow I and II on paintings were carried out with the aid of X-ray diffraction [1] or by SEMEDS and were based, as distinguishing factor, on the presence or the absence of silicon [5]. Undoubtedly, the recently available Raman microscopy, due to its high spatial resolution, sensibility and specificity, represents a far more powerful tool to identify and distinguish the two crystallographic types. Hopefully, more Raman microscopy or micro X-ray diffraction studies of leadetin yellow samples will be carried out both to determine other occurrences of the combined presence of leadetin yellow type I and II and to help explain the reason behind this combined use.
68
I. Borgia et al. / Journal of Cultural Heritage 8 (2007) 65e68
References [1] H. Ku¨hn, Leadetin yellow, Studies in Conservation 13 (1968) 7e33 (Reprinted with revisions in: Artists’ Pigments, a Handbook of their History and Characteristics, vol. 2, National Gallery of Art, Washington, 1993). [2] M.P. Merrifield, Original Treatises on the Arts of Paintings, John Murray, London, 1849. [3] R.J.H. Clark, L. Cridland, B.M. Kariuki, K.D.M. Harris, R. Withnall, Synthesis, structural characterisation and Raman spectroscopy of the inorganic pigments lead tin yellow types I and II and lead antimonite yellow: their identification on medieval paintings and manuscripts, Journal of the Chemical Society, Dalton Transactions (1995) 2577e 2582. [4] E. Martin, A.R. Duval, Les deux varie´te´s de jaune de plomb et d’e´tain: e´tude chronologique, Studies in Conservation 35 (1990) 117e136.
[5] N. Penny, M. Spring, Veronese’s paintings in the national gallery, Technique and Materials: Part I. National Gallery Technical Bulletin 16 (1995) 5e29. [6] I. Borgia, B.G. Brunetti, P. Moioli, C. Seccaroni, A. Sgamellotti, Four anomalous pigments in Perugino’s palette: Statistics, context, hypotheses, in: The Painting Technique of Pietro Vannucci, called the Perugino, Workshop Proceedings, Perugia 13e14 April, Nardini Editore, Firenze, 2003, pp. 29e41. [7] C. Ricci, C. Miliani, I. Borgia, B.G. Brunetti, A. Sgamellotti, C. Seccaroni, P. Passalacqua, The Perugino’s palette: integration of an extended in situ XRF study with aimed Raman scattering measurements, Journal of Raman Spectroscopy 35 (2004) 616e621. [8] K. Sakellariou, C. Miliani, A. Morresi, M. Ombelli, Spectroscopic investigation of yellow majolica glazes, Journal of Raman Spectroscopy 35 (2004) 61e67. ¨ ber den in der Malerei verwendeten gelben Farbstoff der [9] R. Jacobi, U alten Meister, Angewandte Chemie 54 (1941) 28e29.