Characterization of Yellow and Red Natural Organic Colorants on Japanese Woodblock Prints by EEM Fluorescence Spectroscopy

Abstract

As part of a project designed to systematically identify colorants on Japanese woodblock prints, excitation–emission matrix (EEM), or three-dimensional, fluorescence spectroscopy, equipped with a fiber optic probe, was used to characterize natural yellow and red organic colorants on 18th-century Japanese prints without taking samples. This analysis technique collected emission spectra in the visible region for a sequence of excitation wavelengths at 10 nm steps from 250 to 600 nm. The resultant data set provided characteristic excitation/emission patterns that were used to identify several natural colorants, including safflower, madder, sappanwood, gamboge, flavonoids, berberines, and turmeric. In combination with other non-sampling methodologies, including x-ray fluorescence and fiber optic reflectance spectroscopy, most colorants on the prints were quickly and non-destructively characterized. Based on examination of 213 prints, several patterns of colorant use were observed. The prints often contained more than one yellow, red, or blue colorant. From 1781 to 1801, considered the Golden Age of the Japanese print, it was common to find multiple types of yellows, reds, and blues on a single print. The colorant madder was identified on many of the prints, while gardenia and berberine-containing dyes were found on none. This paper presents the theory, experimental parameters, and limitations of the EEM fluorescence technique. The technique is illustrated using the analysis results of four Japanese woodblock prints.

Keywords:

• EEM fluorescence spectroscopy
• Japanese prints
• natural organic colorants

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Erratum

Acknowledgements

The authors are grateful to Kathryn Richardson (Arnold Arboreteum) and Allaire Diamond (Williston, Vermont) for supplying Malus sieboldi and Coptis trifolia reference samples for analysis. Also commendations go to Arianna McQuillen and Kaeley Ferguson for conscientiously analyzing the set of Japanese prints by EEM fluorescence and FORS. Katrina Bartlett's assistance in the initial formulation of organic colorants, help in printing them to create reference samples, and their subsequent analysis early in this project are greatly appreciated.

ORCID

Joan Wright http://orcid.org/0000-0002-0870-5238

Sources of Materials

Cherry wood blocks, rice starch, animal glue, alum

McClain's Printmaking supplies

15685 SW 116th Avenue PMB 202

King City, OR 97224

Japanese Paper: Kizuki Hosho

Hiromi Paper Inc.

2525 Michigan Ave.

Bergamot Station Unit G-9

Santa Monica, CA 90404

Tanaka Nao Dye Supplies Store

Matsubara-dori, Karasuma nishi-iru

Shimogyo-ku

Kyoto 600-8427

Japan

www.tanaka-nao.co.jp

Traditional Japanese Colorants and Pigments

Workshop Kin no Himacho (Golden Fleece)

Matsubara-dori, Higahshinotorin higashi-iru

Shimogyo-ku

Kyoto 600-8086, Japan

www.hitsuji.co.jp

Japanese madder

Résumé - Dans le cadre d'un projet conçu pour identifier systématiquement les colorants sur les gravures sur bois japonaises, on a utilisé une matrice d'émission-excitation de fluorescence (MEEF), par spectroscopie de fluorescence frontale tridimensionnelle avec sonde de fibre optique, afin de caractériser les colorants organiques naturels jaunes et rouges sur des œuvres du 18^ème siècle, sans prélever des échantillons. Ce type d'analyse a permis de recueillir des spectres d'émission dans la région visible, entre 250 à 600 nanomètres, sur des longueurs d'onde d'excitation à 10 nanomètres d’intervalle. L'ensemble de données a fourni des modèles caractéristiques d’émission-excitation qui ont été employés pour identifier plusieurs colorants naturels, y compris le carthame, la garance, le bois de sapan, la gomme-gutte, les flavonoïdes, les berbérines et le curcuma (safran des Indes). En combinaison avec d'autres méthodologies sans prélèvement, y compris la spectrométrie de fluorescence des rayons X et la spectroscopie de réflexion par fibre optique, la plupart des colorants ont été identifiés rapidement et de façon non destructive. L'examen de 213 impressions a permis plusieurs observations sur l'utilisation typique des colorants. Les impressions contiennent souvent plus d’un type de colorant jaune, rouge, ou bleu. Entre 1781 et 1801, période considérée comme l'âge d'or de la gravure sur bois au Japon, il était courant de retrouver sur la même œuvre de multiples types de jaune, de rouge et de bleu. La garance a été identifiée sur plusieurs impressions, tandis qu’aucune ne contenait des colorants à base de gardénia ou de berbérine. Cet article présente la théorie, les paramètres expérimentaux et les limitations de la technique MEEF, à travers les résultats d'analyse de quatre gravures sur bois japonaises. Traduit par Bruno Pouliot, Mireille Brulotte, et André Bergeron.

Abstrato - Como parte de um projeto para identificar de maneira sistemática os corantes japoneses em xilogravuras, excitação-matriz de emissão (EEM), ou espectroscopia fluorescente tridimensional, equipada com uma sonda de fibra ótica, foi utilizada para caracterizar os corantes orgânicos naturais amarelo e vermelho nas impressões do século XVIII, sem recolher amostras. Essa técnica de análise coleta emissão espectral na região visível para uma sequência de excitação no comprimento de onda em etapas de 10 nm de 250 a 600 nm. O conjunto de dados resultantes fornece um padrão de características de excitação/emissão que foi usado para identificar vários corantes naturais, incluindo o cártamo, garana, leguminosas, gamboge, flavonoides, berberinas e açafrão. Em combinação com outras metodologias de não-amostragem, incluindo raio X fluorescente e fibra ótica de refletância espectroscópica, a maioria dos corantes nas gravuras foram identificados rapidamente e sem destruição. Baseado no exame de 213 gravuras, vários padrões de corantes foram caracterizados. As gravuras frequentemente contém mais de um corante amarelo, vermelho ou azul. De 1781 a 1801, período considerado a Idade de Ouro da gravura japonesa, era comum utilizar múltiplos tipos de amarelos, vermelhos e azuis em uma só gravura. O corante mais madder foi identificado em várias impressões, enquanto gardênia e corantes contendo berberina não foram encontrados em nenhuma. Esse trabalho apresenta a teoria, os parâmetros experimentais e as limitações da técnica EEM fluorescente. A técnica é ilustrada usando os resultados da análise de quatro xilogravuras japonesas. Traduzido por Valeria Gauz, Francisco Vieria e Beatriz Haspo.

Resúmen - Como parte de un proyecto diseñado con el fin de identificar en forma sistemática colorantes naturales en grabados en madera japoneses, se usó espectroscopía de fluorescencia de matriz de excitación-emisión (MEE), o espectroscopía de fluorescencia tridimensional, con fibras ópticas, para caracterizar colorantes naturales orgánicos amarillos y rojos en grabados japoneses del siglo XVIII sin sacar muestras. Con esta técnica analítica se adquirieron espectros de emisión en el rango visible del espectro, desde 250 hasta 600 nm, con una secuencia de longitudes de onda de excitación separadas por 10 nm. El conjunto de datos resultante dió patrones de excitación-emisión característicos que se usaron para identificar varios colorantes naturales, incluyendo cártamo, rubia, madera de sapán, gutagamba, flavonoides, berberinas, y cúrcuma. En combinación con otras metodologías no invasivas, incluyendo la fluorescencia de rayos X y la espectroscopia de reflectancia con fibras ópticas, la mayoría de los colorantes en los grabados fueron caracterizados de manera rápida y no destructiva. En base al examen de 213 grabados fueron observados varios patrones en el uso de colorantes. Los grabados frecuentemente contenían más de un colorante amarillo, rojo, o azul. En grabados que datan desde 1781 hasta 1801, considerado como el período de oro del grabado japonés, es común encontrar múltiples amarillos, rojos y azules en la misma obra. El colorante rubia fue identificado en muchos de los grabados mientras que colorantes basados en gardenia y berberina no fueron encontrados en ninguno. Este artículo presenta la teoría, los parámetros experimentales, y las limitaciones de la técnica de fluorescencia MEE. El uso de la técnica se ilustra con los resultados analíticos obtenidos en cuatro grabados en madera japoneses. Traducido por Silvia Centeno y Amparo Rueda.

Additional information

Notes on contributors

Michele Derrick

Michele Derrick is the Schorr Family Associate Research Scientist at the Museum of Fine Arts, Boston, where she has worked since 1995. She was instrumental in the development of CAMEO, an online database for information on materials used in conservation and works of art (cameo.mfa.org). Prior to 1995, she worked as a scientist at the Getty Conservation Institute in Los Angeles for 12 years. A chemist by training, Michele's expertise is in the area of infrared microspectroscopy and she is the author of Infrared Spectroscopy in Conservation Science (Los Angeles: Getty Conservation Institute, 1999). She was also the editor-in-chief of the Journal of the American Institute for Conservation from 2002 to 2014. Address: Museum of Fine Arts, Boston, 465 Huntington Ave., Boston, MA 02115, USA. Email: [email protected].

Richard Newman

Richard Newman is Head of Scientific Research at the Museum of Fine Arts, Boston, where he has worked as a research scientist since 1986. He has a BA in Art History (Western Washington University), MA in Geology (Boston University) and completed a 3-year apprenticeship in conservation and conservation science at the Center for Conservation and Technical Studies, Fogg Art Museum, Harvard University. He has carried out research on a wide range of cultural artifacts, from stone sculpture of the Indian subcontinent to the paintings of Diego Velázquez. Address: As for Derrick. Email: [email protected].

Joan Wright

Joan Wright is the Bettina Burr Conservator at the Museum of Fine Arts, Boston, where she has worked since 1998. She is the conservator in charge of the care of Japanese woodblock prints, Indian and Islamic paintings and illustrated books and manuscripts. From 2005 to 2010 with museum colleagues, she raised funds for and contributed to a project to image, accession, condition survey and re-house the museum's renowned collection of Japanese prints. Prior to 1998, she worked at the Worcester Art Museum and the Fine Arts Museums of San Francisco as a conservator of works of art on paper. Since 2004, she has been a member of the Print Council of America. Essays for MFA Publications include “Brush to Block: Hokusai Observed” in Hokusai, 2015. Address: As for Derrick. Email: [email protected].