Proceedings of the Forum on the Conservation of Thangkas

Proceedings of the Forum on the Conservation of Thangkas Special Session of the ICOM-CC 15th Triennial Conference, New Delhi, India, September 26, 2008 Hosted by the Working Group on Ethnographic Collections, the Textiles Working Group and the Paintings Working Group Editors: Mary Ballard and Carole Dignard Published by the International Council of Museums – Committee for Conservation (ICOM-CC) © ICOM-CC 2009 Thangka Production in the 18th – 21st Centuries: Documenting the Introduction of Non-Traditional Materials into Himalayan Painting Practice Jennifer Mass, Jo-Fan Huang, Betty Fiske, Ann Shaftel, Xian Zhang, Richard Laursen, Courtney Shimoda, Catherine Matsen and Christina Bisulca ABSTRACT: This project investigates the materials and techniques used by Tibetan artists. Six Tibetan thangkas were analyzed by infrared reflectography, energy dispersive x-ray fluorescence, Fourier transform infrared microspectroscopy, Raman spectroscopy, scanning electron microscopy-energy dispersive spectroscopy, and high-performance liquid chroma-tography. The analysis has suggested that three thangkas of the eighteenth - nineteenth century have a traditional palette, which includes azurite, vermilion, orpiment, bronchantite, red lead, dolomite, magnesite, organic red with calcite or magnesite substrate, and alumino-silicate clay minerals. Another late nineteenth or early twentieth century thangka shows the use of Western pigments such as emerald green, ultramarine, calcite, gypsum, chrome yellow, gold color from brass powder, and red and yellow dyes with barium sulfate substrates. Two twentieth century thangkas made for the tourist trade revealed a twentieth century palette such as titanium dioxide, phthalocyanine blue, phthalocyanine green, and other pigments such as red lead, chrome yellow, barium sulfate, and gypsum. Introduction A Himalayan thangka, or rolled-up image, is a sacred painting (Figure 1) in opaque distemper that has a complex mount of textiles and hanging dowels (Figure 2). The production of Tibetan Thangkas has been influenced greatly by Buddhist nomadic monasticism and cultural exchange as well as economic exchanges between Tibet and the neighboring Himalayan countries. The scientific examination of twenty-five thangkas have been previously published (twenty-three 17th century Tibetan thangkas1, 2, 3, a 15th century Nepali thangka4 and an 18th-19th century Bonpo Tibetan thangka5). Currently, studies on the introduction of synthetic and Western pigments into Tibet are ongoing at Winterthur and the Philadelphia Museum of Art. This study, a collaborative effort between conservators and museum scientists, examines the evolution of Himalayan thangka painting materials through the analysis of six thangkas dating from the 18th through the 21st centuries. Special attention was given to foreign trade from China and India, which directly impacted the availability of artists’ materials in Tibet via local trading routes. The six Tibetan thangkas were selected to represent the evolution of the artists’ palette in Thangka production: one from eighteenth century, two from eighteenth to nineteenth centuries, one from late nineteenth century or early twentieth centuries, and two from the late twentieth or early twenty-first century.     108 Figure 1: A nomadic Buddhist gathering where thangkas were worshipped. Source: Tibetan Thangka Painting: Methods & Materials (Jackson & Jackson, 1984). Figure 2: Elements of a thangka. Source: A. Shaftel (1986), JAIC 25. Methodology Analytical methodology included the use of energy-dispersive x-ray fluorescence (EDXRF), Fourier transform infrared microspectroscopy (FTIR), Raman microspectroscopy, Liquid Chromatography - Diode-Array Detector- Mass Spectrometry (LC-DAD-MS) analysis, Fibre Optic Reflectance Spectrometry (FORS), and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS). Description of the Thangkas and Analytical Results Thangka A (Figure 3, left): The earliest thangka studied, dating from the 18th century. It is thought to be from either Lhasa or eastern Tibet. It depicts two Arhats, one of the attendants (Hvashang) and two of the Guardian Kings. Analysis has identified dolomite in the ground as well as cinnabar as a red pigment (Figure 3, right). Thangka B (Figure 4, left): This thangka, from the 18th-19th century, is thought to be from the Tsang region of Central Tibet. It is from a Gelugpa context, and depicts Sakyamuni surrounded by Gelug teachers. Analysis has shown the presence of antlerite and brochantite (Figure 4, right, top). Significant quantities of arsenic suggests that orpiment was used as a yellow pigment. (Figure 4, right, bottom).     109 1.4 4964 Tibetan Thangka s3 brown a *IMP00243 Dolomite, Chester Collection, #AHC3060, PMA, tran 1.3 1.2 1.1 1.0 Absorbance 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 2600 2400 2200 2000 1800 1600 1400 1200 1000 Wavenumbers (cm-1) 1400 Vermilion-RCL 1200 Abs 1000 800 600 400 200 60000 red pigment spot 1 50000 Arb 40000 Figure 3: Left: Thangka A.. Right, top: FTIR spectra of dolomite in ground. Right, bottom: Raman spectrum of red pigment: cinnabar is identified in the sample. 30000 20000 10000 350 300 250 200 150 Arbitrary units 4958 Tibetan Thangka S3 green b Abs 1091 990 0.10 3490 3565 0.15 0.05 0.00 Brochantite, SI-NMNH, #82331-1, PMA, tran 3565 0.6 Abs 1088 0.8 0.4 0.2 -0.0 3573 988 Abs 0.6 3489 Antlerite, SI-NMNH, #R6076, PMA, tran 0.8 0.4 0.2 3500 3000 2500 2000 1500 1000 Wavenumbers (cm-1) x 1E3 Pulses 12 10 8 Fe Cu Ca As Ca Fe Cu As 6 4 Figure 4: Left: Thangka B. Right, top: FTIR spectrum showing presence of antlerite and brochantite. Right, bottom: XRF spectrum suggesting use of orpiment as a yellow pigment.  2 0 0 5 10 - keV - 15     20 110 Thangka C (Figure 5, left): This thangka is from central Tibet, and depicts Amitabha surrounded by Sukhavati pure land/paradise, late 18th to 19th century. Its paint layer which contained a bright orange pigment, was partially masked by soot deposits (Figure 6). The green pigment malachite was identified (Figure 5, right). The green color in the silk mount was analysed and found to be a mixture of blue and yellow colorants: indigo and rutin (Figure 7). The exact Himalayan plant sources for these dyes are not known; perhaps they were imported. Figure 5: Left: Thangka C. Right: Cross-sections of green sample: Top: Visible light photomicrograph. Center: backscattered electron. Bottom: X-ray map images (bottom, red = Si, green = Cu) showing presence of copper green (malachite) overlying clay ground. Figure 6: Cross section of paint layer, Thangka C. Obfuscation of orange pigment at surface due to soot deposit during devotional use (brown surface layer partially masking the orange pigment).     111 Figure 7: LC-MS-DAD analysis of the green silk mount in Thangka C. Indigo (blue) and rutin (yellow) were identified. Ca Ba Fe 5 Cu As 10 - keV - Figure 8: Left: Thangka D. Right, top: Cross-section photomicrograph of chrome yellow applied over ultramarine blue (visible light, 200x magnification). Right, bottom: ED-XRF data of green colorant, revealing Cu and As.     112 Thangka D (Figure 8, left): This is a mid-20th century thangka depicting Tsonkhapa, founder of the Gelug lineage, possibly of Mongolian or Sino-Tibetan/Amdo, in the folk art tradition. The cross-section photomicrograph (Figure 8, top right) shows chrome yellow applied over ultramarine blue. ED-XRF analysis (Figure 8, bottom right) of a green colorant revealed the presence of copper (Cu) and arsenic (As). This data in conjunction with FTIR analysis indicated the use of emerald green pigment. Thangka E (Figure 9, left): Thangka purchased in 21st century China, depicting the White Tara, or bodhisattva of compassion and serenity. The thangka was made specifically for the tourist trade and marketed as very old. The Raman spectrum (Figure 9, right) shows use of phthalocyanine green (633 nm laser for CAMEO reference spectrum, top; 785 nm laser for thangka, bottom spectrum). The XRF spectrum (Figure 10) suggests the use of chrome yellow. Note high manganese (Mn) content due to ‘artificial soot’ on surface: the piece has been artificially aged by darkening with a manganese-based pigment (Figure 10). 4998 Phthalocyanine Green 12 1539 65000 60000 55000 50000 777 30000 1215 25000 Figure 9: Left: Thangka E. Right: The Raman spectrum shows use of phthalocyanine green (633 nm laser for CAMEO reference spectrum, top; 785 nm laser for thangka, bottom spectrum). 1340 35000 1285 686 Arbitrary units 40000 742 45000 20000 15000 10000 5000 0 -5000 200 400 600 800 1000 1200 1400 1600 Arbitrary units     113 x 1E3 Pulses 15 10 Mn Ba Fe Cr Ca Zn Pb Mn Ca Ba Cr Fe Zn Pb 5 0 0 5 10 - keV - 15 20 Figure 10: Thangka E, XRF spectrum suggesting use of chrome yellow. Note high manganese (Mn) content due to ‘artificial soot’ on surface. Figure 11: Left: Thangka F. Right: Visible light, backscattered electron imageing, and x-ray map images from a gilded region (green = Au, blue = Ti, and red = Si).     114 Thangka F (Figure 11, left): *IOD00216 Phthalocyanine blue, age 55 yrs, Krebs, Forbes 95, SCC, tran AL4965 hazy blue *IMP00078 Prussian blue, Winsor & Newton, PMA, tran 1420 1.2 1334 This thangka is modern in both its iconography and origin. Similar to Thangka E, it was purchased on the tourist market in Asia in 2006 as an ‘old’ thangka. A gilded area was examined by visible light, by backscattered electron imageing, and by x-ray mapping (Figure 11, right); the latter technique identified the presence of gold (Au), titanium (Ti) and silicium (Si), which are indicative of modern materials. The FTIR spectrum (Figure 12) showed the use of Prussian blue and phthalocyanine blue synthetic pigments. 2078 1.1 1.0 1422 0.9 Absorbance 1165 0.8 0.7 0.6 1164 0.5 0.4 2081 1333 0.3 0.2 0.1 -0.0 2200 2000 1800 1600 1400 1200 1000 Wavenumbers (cm-1) Figure 12: FTIR spectrum of Thangka F showing use of Prussian blue and phthalocyanine blue pigments. Discussion and Conclusions Thangkas A, B and C, the 18th and 19th century thangkas, were found to have a traditional Himalayan palette, consisting of vermilion, red lead, and lac dye reds, orpiment (As2S3), and iron ochre yellows, malachite, antlerite [Cu2Cl(OH)3], and brochantite [Cu4SO4(OH)6] greens, azurite and organic blues (likely indigo), carbon blacks, calcite whites, and grounds of clay, magnesite (MgCO3), or a mixture of the two. The mid-20th century Thangka D palette documents the importation of synthetic and Western pigments into the Himalayan region. These pigments include chrome yellow PbCrO4, artificial ultramarine, and emerald green [Cu(C2H3O2) 2. 3Cu(AsO2)2], as well as a barium white ground. They are used in conjunction with more traditional artists’ materials, including vermilion and red lead, magnesite and gypsum. In Thangkas E and F, the 21st century thangkas, we see the use of the phthalocyanine blue and green pigments, in addition to as yet unidentified synthetic red lake pigments.     115 While Prussian blue was identified in the previously mentioned study of a 18th-19th century Bonpo thangka5, it is notable that pigments introduced in the early 19th century in the West do not show up in Himalayan thangkas until the 20th century. However, further analysis of late 19th and early 20th century thangkas is necessary to more precisely determine the date of introduction of these materials. An 1840s account of pigments imported into Nepal and then into Tibet by the British East India Company included lead white, indigo, verdigris and sandalwood.6 Endnotes 1. Duffy, K. and J. Elgar, 1995, “An investigation of palette and color notations used to create a set of Tibetan Thangkas”, in book: Historical Painting Techniques, Materials, and Studio Practice, edited by A. Wallert, E. Hermens, and M. Peek (The Getty Conservation Institute: Los Angeles), pp. 78-84. 2. Duffy, K. and J. Elgar, 1999, “Examination of thangkas from Central and Eastern Tibet”, in book: Sixth international conference on ‘non-destructive testing and microanalysis for the diagnostics and conservation of the cultural and environmental heritage’, Rome, 17-20 May 1999, edited by M. Marabelli, C. Parisi, S. Gagliardi, G. M. Parisi and G. Torcinaro, vol. 3, pp. 1751-66. 3. Duffy, Kate and Jacki Elgar, 2003, “Five Protective Goddesses (Pancaraksha): a study of color notations and pigments”, in book: Scientific Research in the Field of Asian Art: Proceedings of the First Forbes Symposium at the Freer Gallery of Art, edited by Paul Jett, Janet G. Douglas, Blythe McCarthy and J. W. Winter (Archetype Publications Ltd: London). pp. 164-169. 4. Leona, Marco and Sandhya S. Jain, 2005, “Crossing the line: the interplay between scientific examination and conservation approaches in the treatment of a fifteenth-century Nepali thangka”. In book: Scientific Research on the Pictorial Arts of Asia: Proceedings of the Second Forbes Symposium at the Freer Gallery of Art, edited by Paul Jett, John Winter and Blythe McCarthy (Archetype Publications Ltd: London), pp. 125-134. 5. Richard R. Ernst, “Arts and Sciences. A Personal Perspective of Tibetan Painting”, Chimia, 55 (2001), pp. 900-914. 6. Hodgson, Brian Houghton, 1972 (1831). “The Commerce of Nepal”, in book: Essays on the Languages, Literature, and Religion of Nepal and Tibet: Together with further papers on the Geography, Ethnology, and Commerce of those Countries. Philo Press: Amsterdam, pp. 91-121. Hodgson was a British East India Company resident of Nepal for nearly two decades. In this paper originally published in 1831, Hodgson used Nepal as the subject and recorded its import and export with special commentary about Tibet. He briefly touched upon the early trade between Newar people of valley of Nepal and India and Tibet and then demonstrated Nepal as a trade center and bridge between British India and Tibet. Notable imported goods from India to Nepal and some of them were further exported into Tibet. Those were fabrics of many kinds, threads, coral, diamond, precious stones (emeralds, rubies, and sapphires), ambers of various kinds, chank,     116 coweis, gold mohur, golochan, indigo, animal skin of various kinds, saltpeter, brimstone, quicksilver, "singraf" or vermilion cinnabar, “China” and “Country” red lead, ruskappor, camphor, white sandal, Zangar or verdigris, white lead, minerals of various types, hardware, dried fruits, spices, and misc. Hodgson commented that there was a huge demand for opium and indigo from China and Mongolia through Tibet. Tibetan liked English broad cloth for clothing, and purchased some cotton fabric to cover paintings. Hodgson also mentioned another trade route between Russia and China. The Russian imports to China consist of products from Russia, England, and North America; the later two were often in large quantity, usually about half of the imports. Hodgson also noted the direct trade between Nepal and China. BIOGRAPHIES: Jennifer Mass, Betty Fiske, Courtney Shimoda, W. Christian Petersen and Catherine Matsen are from Winterthur/University of Delaware Program for Art Conservation (WUDPAC), USA. Jo-Fan Huang is from the Philadelphia Museum of Art. Xian Zhang and Richard Laursen are from Boston University. Ann Shaftel is a Fellow of IIC, a Fellow of AIC and a member of CAPC in Canada. She has an M.A. in Asian Art History and and M. S. in Conservation. She has worked preserving thangkas since 1970, including work for major museums worldwide and monasteries in Bhutan, Sikkém, Nepal and Tibetan communities in Northern India, including the Dalai Lama’s museum. CONTACT: Ann Shaftel, Tsöndrü Thangka Conservation, 6201 Shirley Street, Halifax, Nova Scotia B3H 2N3, Canada. Tel. (902) 422-2327. Web: www.TSONDRU.com. Email: [email protected] . Disclaimer These conference session papers are published and distributed by the International Council of Museums – Committee for Conservation (ICOM-CC), with authorization from the copyright holders. They are published as a service to the world cultural heritage community and are not necessarily reflective of the policies, practices, or opinions of the ICOM-CC. Information on methods and materials, as well as mention of a product or company, are provided only to assist the reader, and do not in any way imply endorsement by the ICOM-CC.     117