Fluorimetric Analysis of the Constituent Dyes Within Daylight Fluorescent Pigments: Implications for Display and Preservation of Daylight Fluorescent Artwork

Abstract

Daylight fluorescent pigments are formulated with a select range of colorants that both absorb and emit strongly in the visible region. To ensure best practices in the preservation and authentication of artworks that contain daylight fluorescent colorants, this study investigates the fluorescent dye formulation behind daylight fluorescent pigments by specifically examining the DayGlo daylight fluorescent pigment range. A recently developed extraction–separation protocol was applied to isolate individual dye components of each pigment for fluorescence analysis. Through fluorimetric analysis at the constituent dye level, the formulation behind each pigment's observed hue was characterized and interaction by energy transfer between specific dye pairs was established. This research finds that complex dye formulations employed in daylight fluorescent pigment manufacture raise several implications for the display and treatment of this modern palette.

Résumé – Les pigments fluorescents de jour sont formulés avec une gamme de colorants qui absorbent et émettent fortement dans la région visible du spectre électromagnétique. Afin d'assurer des pratiques exemplaires dans la préservation et l'authentification des œuvres qui contiennent des colorants fluorescents de jour, la présente étude examine la formulation de colorants fluorescents qui composent la gamme de pigments fluorescents de jour de la marque DayGlo. Un protocole d'extraction-séparation récemment mis au point a été appliqué pour isoler les colorants individuels de chaque pigment pour l'analyse par fluorescence. Grâce à l'analyse fluorimétrique des colorants constitutifs, la formulation de chaque pigment a été caractérisée et l'interaction par transfert d'énergie entre des paires de colorants spécifiques a été établie. Cet article conclut en discutant de certaines implications que les formulations complexes de colorants utilisées dans la fabrication des pigments fluorescents de jour soulèvent pour l'exposition et les traitements de conservation-restauration de cette palette de couleurs modernes.

Resumen – Los pigmentos fluorescentes a la luz de día están formulados con una selecta gama de colorantes que, absorben tanto como emiten fuertemente en la región visible. Para asegurar la mejor práctica en la preservación y en la autenticación de obras de arte que contienen colorantes fluorescentes a la luz de día, este estudio investiga la formulación de tintes fluorescentes contenida en los pigmentos fluorescentes a la luz de día al examinar específicamente la gama de los pigmentos fluorescentes a la luz de día de DayGlo. Para hacer una análisis de fluorescencia se utilizó un protocolo recientemente desarrollado de extracción-separación para aislar los componentes individuales de tintes de cada pigmento. A través del análisis fluorimétrico a nivel del tinte constitutivo, se caracterizó la formulación contenida en la tonalidad observada en cada pigmento, y se estableció la interacción por transferencia de energía entre pares de tintes específicos. Esta investigación encontró que las formulaciones complejas de tintes empleados en la manufactura de pigmentos fluorescentes a la luz de día plantea varias implicaciones para la exhibición y tratamiento de esta moderna paleta de colores.

Resumo – Pigmentos fluorescentes à luz do dia são formulados com uma gama selecionada de corantes que tanto absorvem como emitem fortemente na região visível. Para garantir as melhores práticas de preservação e autenticação de obras de arte que contêm corantes fluorescentes à luz do dia, este estudo investiga a formulação do corante fluorescente dos pigmentos fluorescentes à luz do dia através do exame específico da gama de pigmentos fluorescentes da luz do dia DayGlo. Um protocolo desenvolvido recente de extração-separação foi aplicado para isolar corantes individuais componentes de cada pigmento para análise de fluorescência. Através da análise fluorimétrica dos níveis de corantes constituintes, a formulação de cada matiz de pigmento observado foi descrita, e a interação por energia transmitida entre pares específicos de corantes foi estabelecida. Essa pesquisa constata que as complexas formulações de corantes utilizados na fabricação dos pigmentos fluorescentes da luz do dia suscitam várias implicações para a exposição e o tratamento dessa paleta moderna.

Keywords:

• fluorescence spectroscopy
• energy transfer
• daylight fluorescent pigment

Acknowledgments

The authors would like to thank Alf Meilak (School of Chemistry, University of Melbourne) for enabling access to the Carey Fluorescence Spectrophotometer, and Tom DiPietro (DayGlo Color Corporation) for providing samples of the DayGlo pigment powder samples.

Source of Materials

DayGlo Daylight fluorescent pigment range (A11-A19) DAYGLO Color Corporation

4515 St. Clair Avenue

Cleveland, OH 44103

216-391-7070

[email protected]

All chemicals used

Merck KGaA Frankfurter Str. 250

64293 Darmstadt

Germany

[phone]

Fax: [phone]

[email protected]

Sep-Pak Plus tC18-environmental cartridge (37-55μm silica)

Waters Corporation

34 Maple Street

Milford, MA 01757

508-478-2000

800-252-4752

Kieselgel 60 F254 pre-coated TLC sheets

Macherey Nagel Inc.

2850 Emrick Blvd.

Bethlehem, PA 18020, USA

484-821-0984

Fax: [phone]

[email protected]

K2 Cut-off filter

Hoya FilterKenko Tokina Co., Ltd

3-9-19 Nishi-Ochiai, Shinjuku-ku

Tokyo 161-8570, Japan

[phone]

[email protected]

Tokyo Blue Band-pass Filter

Lee Filter

Central Way, Walworth Business Park

Andover, Hampshire, SP10 5AN, UK

[phone]

http://www.leefilters.com

Additional information

Notes on contributors

Elizabeth Hinde

Elizabeth Hinde is a postdoctoral researcher at the Laboratory for Fluorescence Dynamics at the University of California, Irvine. She has a BSc in Chemistry, MA in Cultural Material Conservation, and a PhD that focused on the characterization of the spectroscopic properties of daylight fluorescent pigments. Her research interests in the field of conservation relate to the chemical and optical analysis of fluorescent pigments and dyes. She is currently working with fluorescence lifetime imaging microscopy, fluorescence correlation spectroscopy and fluorescence resonance energy transfer based detection methods. Address: Laboratory for Fluorescence Dynamics, University of California, Irvine, Biomedical Engineering Department, 3208 Natural Sciences II, Irvine, CA 92697-2715, USA, email: [email protected]

Petronella Nel

Petronella Nel is a lecturer and researcher at the Centre for Cultural Materials Conservation (CCMC) in the School of Historical and Philosophical Studies at the University of Melbourne. She has qualifications in art and science with a BSc (Honours), PhD in Chemistry, and a MA in Cultural Materials Conservation. She is involved with teaching and research programs at CCMC. Her research interests include the non-invasive analysis of artefacts, and the development of scientific techniques to conservation. More specifically her current research involves: the analysis and assessment of adhesives used to repair archaeological pottery with the Cypriot pottery Collection being used as a case study; a study of ochre-earth pigments using micro-PIXE, micro-XRF, and micro-XRD; and the development of the Chemistry Collection at the University of Melbourne. Address: Centre for Cultural Material Conservation, University of Melbourne, Parkville, VIC 3010, Australia, email: [email protected]

Robyn Sloggett

Robyn Sloggett is Associate Professor and Director of the Centre for Cultural Materials Conservation (CCMC) at the University of Melbourne. She has qualifications in Art History, Philosophy, and Cultural Materials Conservation. As Director of the CCMC she manages the diverse conservation, teaching, and research programs of the Centre. These programs include responsibility for the conservation of the cultural collections of the University of Melbourne (with over 32 separate collections owned or managed by the University) and the provision of a large program for external clients with specialist expertise in painting, frame, paper, objects, and textiles conservation. The CCMC also delivers the only comprehensive post-graduate conservation professional programme in the Australasia-Pacific region, as well as courses in Art Authentication and Photographic Preservation. Her research interests include programs in cultural materials conservation that focus on the materials and techniques of artists (particularly in Australia and South East Asia), ethical and philosophical issues in cultural materials conservation, and the development of scientific techniques for conservation. Address: As for Nel; email: [email protected]

Ann Roberts

Ann Roberts is Associate Professor and Deputy Head of the School of Physics, University of Melbourne. She has a BSc (Honours) and PhD in Physics. Her research interests include optical physics, imaging, microscopy, nanophotonics, and metamaterials. In collaboration with the Centre for Cultural Materials Conservation she also investigates how imaging modalities such as electronic speckle pattern interferometry (ESPI) can be applied to evaluate the mechanical properties of artist's materials, in particular the mechanical response of western artists' materials in tropical environments. Address: School of Physics (David Caro Building), The University of Melbourne, VIC 3010, Australia, email: [email protected]