Identity and connections within medieval heritage: color in the illuminated manuscript through the eyes of the molecular sciences and humanities

The characterization and identification of organic dyes is still a challenge within the field of Conservation Science. By exploring the potentialities of microspectrofluorimetry combined with chemometrics, this doctoral project provides the identification of red organic colorants and a comprehensive knowledge of the making of medieval paints. Microspectrofluorimetry (in the visible) allows the simultaneous acquisition of excitation and emission spectra, offering high sensitivity and selectivity combined with good spatial resolution and the possibility of in-depth profiling, which facilitates an accurate identification of dyes and lake pigments. Although lacking the fingerprint capability of vibrational spectra, it offers valuable knowledge into the paint formulation. Recipes’ specificities can provide insight into chronological and location particularities, such as scriptoria, enabling a better understanding of the making of the artists’ materials. The first part focuses on the development and testing of modeling strategies applied to i) a database of historically accurate reproductions of four natural red colorants namely brazilwood, cochineal, kermes and lac dye, used during the Middle Ages; ii) data from artworks, to address the difficulty of analyzing centuries old paints. The first confirmed the potential for microspectrofluorimetry in the assessment of the chromophore’s environment, i.e., the paint formulation, while the second explored the intricacies of the ‘original’ colors and the effectiveness of this methodology to explore similarities between naturally aged paints. This project proves the ability of microspectrofluorimetry as a powerful technique for the characterization of dyes and lake pigments. The historical reconstructions database allowed to pinpoint the main recipes of cochineal lake pigments from the 19th century Winsor & Newton’s database. The artworks database allowed to better understand recipe specificities and for the first time, we could pinpoint a formulation in which lac dye and brazilwood chromophores are admixed, in manuscripts from the Alcobaça scriptorium. In the second part, the methodology developed was tested in two case studies: the Ajuda Songbook and a group of Islamic manuscripts. The first, the oldest of the surviving Galician-Portuguese songbooks, is an unfinished illuminated manuscript, of which there is no knowledge of the circumstances of its production or the reason why it was never finished. The combination of a multi-analytical approach with the methodology developed in this project enabled the complete molecular characterization of the paint colors. It was shown the skillful construction of the paint layers and the richness of the chromatic palette, which demonstrates the desire and the resources to produce a luxurious manuscript. The methodology allowed to propose a production date for the Ajuda Songbook, in which the presence of brazilwood lake pigment and mosaic gold indicates a 14th century date, while the use of orpiment yellow pushes the date back into the 13th century. The second case study is a group of Islamic manuscripts (12th – 15th c.), from Timbuktu, Mali, which due to their rescue and conservation have allowed the study of their materials and techniques. For the first time, the richness and specificities of the paint formulations used were disclosed. It was possible not only to provide an unequivocal molecular characterization of the red colorant, lac dye but also to ascribe specific recipes to the different paint colors. Interestingly, the comparison with the artworks’ database has shown similarities with lac dye formulations found in Portuguese medieval illuminations. Moreover, the full characterization of the paint materials has also revealed severe degradation of the binding media. This approach will allow for better informed decision-making in the conservation process of these manuscripts. The synergy between the multi-analytical approach for the analysis of medieval manuscripts and the new methodology for the study of organic colorants was essential to the study of both case studies. The confocal spectrofluorimetry set-up used, as well as the expertise in the characterization of artworks, enabled in-depth knowledge into the construction of color paints, well beyond the identification of the single fluorophore

The knowledge of master dyers revealed by HPLC-DAD and UHPLC-HRMS/MS

UIDB/00749/2020 UIDP/00749/2020This work provides new knowledge on natural yellows used in Iran. Seven biological sources were selected based on interviews with dye masters in Isfahan workshops (Iran). Delphinium semibarbatum, Eremostachys laevigata, Prangos ferulacea, Morus alba, Pistacia vera, Punica granatum, and Vitis vinifera are currently used in these workshops. Aiming to study the dye composition of wool samples dyed with the extracts of the selected biological sources and the changes induced by the dyeing procedures in the original chemical composition of the plant extract, raw materials and dyed wool (by us and in the workshops) were analyzed by HPLC–DAD and UHPLC–HRMS/MS. The main yellows for E. laevigata are luteolin-O-glycosides. In the other plant sources, the main chromophores are based on 3-O-glycosides of kaempferol, quercetin, and isorhamnetin. In pistachio hulls, myricitin derivatives were detected and we propose their use as markers. Generally, the solutions extracted from the wool displayed a higher amount of more polar compounds, but also a higher amount of aglycones. Importantly, the chromatographic profiles of the samples we prepared compared well with 17th c. yellows in Persian carpets, and therefore can be considered highly characterized references for the study of Persian yellowThis work provides new knowledge on natural yellows used in Iran. Seven biological sources were selected based on interviews with dye masters in Isfahan workshops (Iran). Delphinium semibarbatum, Eremostachys laevigata, Prangos ferulacea, Morus alba, Pistacia vera, Punica granatum, and Vitis vinifera are currently used in these workshops. Aiming to study the dye composition of wool samples dyed with the extracts of the selected biological sources and the changes induced by the dyeing procedures in the original chemical composition of the plant extract, raw materials and dyed wool (by us and in the workshops) were analyzed by HPLC–DAD and UHPLC–HRMS/MS. The main yellows for E. laevigata are luteolin-O-glycosides. In the other plant sources, the main chromophores are based on 3-O-glycosides of kaempferol, quercetin, and isorhamnetin. In pistachio hulls, myricitin derivatives were detected and we propose their use as markers. Generally, the solutions extracted from the wool displayed a higher amount of more polar compounds, but also a higher amount of aglycones. Importantly, the chromatographic profiles of the samples we prepared compared well with 17th c. yellows in Persian carpets, and therefore can be considered highly characterized references for the study of Persian yellows.publishersversionpublishe

A First Approach to the Study of Winsor & Newton’s 19th-Century Manufacture of Madder Red Lake Pigments

Funding Information: We are grateful to Winsor & Newton, ColArt Fine Art & Graphics Ltd., for allowing the creation of the archive project. The W&N 19th Century Archive Database, designed by Mark Clarke and Leslie Carlyle, was funded by the Netherlands Institute for Scientific Research (NWO) as part of the De Mayerne Programme and, in the UK, by a Resource Enhancement Grant from the Arts and Humanities Research Council (AHRC). We thank Marta F. Campos for purchasing the Rose Madder 19th-century oil paint tube on eBay and dating it. We also appreciate the comments of the participants at the Dyes in History and Archaeology 41. Funding Information: This work was funded by the Portuguese Foundation for Science and Technology (FCT) of the Ministry of Science, Technology and Higher Education (MCTES) through the Research Units VICARTE (UIDB/00729/2020; UIDP/00729/2020) and LAQV-REQUIMTE (UIDB/50006/2020; UIDP/50006/2020), project MAGICA (PTDC/ART-PER/1702/2021), project REDiscover (2022.02909.PTDC), Vanessa Otero’s 2020.00647.CEECIND and Paula Nabais’s 2021.01344.CEECIND. Publisher Copyright: © 2023 by the authors.This paper focuses on the first investigation of the 19th-century manufacture of red lake pigments obtained from madder by Winsor & Newton (W&N), prominent artists’ colourman at that time. The first approach to their manufacture was carried out by studying the madder entries of the company’s book P1, found in the W&N 19th Century Archive Database. Eleven production records were discovered under names such as Rose Madder, Madder Carmine, Madder Lake and Madder Rose. Three main methods of synthesis were identified and reproduced, revealing three main steps: washing of the madder roots (Rubia tinctorum L.); extraction in acid media and complexation with Al3+ using alum; and precipitation by the addition of salts such as ammonium carbonate and sodium borate. The syntheses were followed by UV-VIS spectroscopy, and the pigments were further characterised by colourimetry, Energy-Dispersive X-Ray Fluorescence Spectrometry (XRF), Fourier Transform Infrared Spectroscopy (FTIR) and High-Performance Liquid Chromatography-Diode Array Detector (HPLC-DAD). They all exhibited a rose hue in a highly insoluble aluminate matrix. Although the dye extraction was incomplete, alizarin, purpurin and pseudopurpurin were identified. An analytical comparison with a Rose Madder 19th-century oil paint tube was also performed by micro-FTIR and microspectrofluorimetry. This work intends to be foundational to a systematic study of the W&N’s 19th-century madder colours aiming to contribute new knowledge towards their identification and preservation in heritage objects.publishersversionpublishe

In-depth phenolic characterization of iron gall inks by deconstructing representative Iberian recipes

UIDB/50006/2020 PTDC / QUI-OUT / 29925/2017Iron-gall ink is one of the most important inks in the history of western civilization. The deep black colour results from Fe3+ complexes with phenolic compounds available in gall extracts. Unfortunately, it induces the degradation of both ink and support over time. Furthermore, our knowledge of these complex molecular structures is limited. This work aims to overcome this gap, revealing essential information about the complex structures of these pigments and dyes that will create a breakthrough in the next generation of conservation treatments. It presents the first in-depth phenolic identification and quantification of extracts and inks, prepared with and without gum arabic (an essential additive in medieval recipes). Five representative Iberian recipes were selected and prepared. Their phenolic profile was analysed by HPLC–DAD and HPLC–ESI–MS, which revealed that the phenolic compounds present in higher concentration, in the gall extracts, are pentagalloylglucose and hexagalloylglucose (0.15 ± 0.01–32 ± 3 mg/mL), except for one recipe, in which gallic acid is the main phenolic. The influence of the ingredients is also discussed by deconstructing the recipes: extracts of additives as pomegranate peel and solvents used in the extraction of the galls (vinegar and white wine) were characterized.publishersversionpublishe

tracing history through luxury pink colors

The authors would like to thank José Alberto Ribeiro, director of Palácio Nacional da Ajuda, and Cristina Pinto Basto, coordinator librarian, for their generous support and rewarding collaboration. We also wish to acknowledge the Laboratory of Biopolymers—Centro de Investigación en Alimentación y Desarrollo, A.C (C.I.A.D., A.C.), Hermosillo, Sonora, México, for providing the samples of mesquite gum used in this work. This research was funded by the Portuguese Science Foundation (Fundação para a Ciência e Tecnologia, Ministério da Educação e da Ciência, FCT/MCTES) and co-financed by the ERDF under the PT2020 Partnership Agreement (POCI-01-0145-FEDER-007265). Project “Try it and you will see that is true”. Recipes and knowledge from Medieval society to the 21th century”, PID2019-108736GB-I00, Ministerio de Ciencia e Innovación. R. J. Díaz Hidalgo, posdoctoral UCO 2020, La producción documental y libraría al Ándalus siglos XIII XV, Plan Propio de Investigación de la Universidad de Córdoba; Publisher Copyright: © 2023, The Author(s).The Ajuda Songbook is an exceptional illuminated manuscript being the only surviving codex of Galician-Portuguese secular poetry; it was produced in the end of the thirteenth century, beginning of the fourteenth century. The diversity of colors accentuated by the presence of lapis lazuli blue and brazilwood pink, demonstrates the desire to produce a sumptuous manuscript. Pink is, in this context, a luxury color and its identification attests to one of the earliest known occurrences of brazilwood in artworks. Scientific analysis showed, for the light pinks, a different formulation from that found in fifteenth-century books of hours and from all historical reconstructions of these colors prepared to date. This knowledge was used to further expand a database previously built in our laboratory and applied to the characterization of pink shades in the Ajuda Songbook. Thirteen brazilwood recipes were selected from seven Medieval treatises and reference materials were prepared based on such historical information. Three types of colors were achieved, defined as translucent rose, rose, and red. The translucent rose was obtained from recipes where egg white is used for extraction, and no other additives are present; rose from recipes with calcium carbonate; and red from a wider range of recipes, in which these ingredients are not mentioned. These colors were then prepared as paints, and analytical results were thus compared with data from the light pinks seen in the Ajuda Songbook’s architectural backgrounds. We were able to reproduce the pink very well using infrared spectroscopy, identifying its main ingredients: calcium carbonate as filler; lead white as the pigment that produces light pink; and the binder as a polysaccharide with a fingerprint similar to mesquite gum. For the chromophore color, the application of chemometrics approaches to molecular fluorescence spectra highlighted a high degree of similarity with the paint reconstructions.publishersversionpublishe

Organic colorants based on lac dye and brazilwood as markers for a chronology and geography of medieval scriptoria: a chemometrics approach

CORES-PD/00253/2012 PD/BD/105895/2014 SFRH/BD/148729/2019 PTDC/LLT-EGL/30984/2017 UIDB/50006/2020 UIDP/50006/2020This work presents the first proof of concept for the use of molecular fluorescence signatures in medieval colours based on lac dye and brazilwood lake pigments. These two important medieval dyes were tested as markers using their UV–Visible emission and excitation spectra. These medieval paints had been previously fully characterized through a multi-analytical approach. In this work, molecular fluorescence spectra were acquired in manuscripts dating from 12th to 15th c., which were produced in monastic scriptoria or workshops. First, the spectral distribution and relative intensity of the emission and excitation spectra were discussed in detail by comparison with reference compounds, including reproductions of paints based on medieval technical texts. It was possible to group the spectra according to recipe specificities. Then, statistical methods (principal component analysis and hierarchical cluster analysis) were applied to the same fluorescence spectra and the generated clusters were compared with the previous ones. Principal component analysis was initially employed to eliminate redundancy in fluorescence data, so minimizing bias on the hierarchical cluster analysis results. Except for some misplaced spectra, the placement of samples per group was confirmed. The outliers resulted from either a poor signal to noise ratio or occurred because certain paints were unique, such as the colour produced by mixing lac dye and brazilwood, which was found in manuscripts from the Alcobaça monastic scriptorium. Previously, by using infrared or Raman spectroscopies, only lac dye could be detected. Notably, these paints compare well with a recipe that was reproduced from the text by Jean Le Begue, in which both dyes were required.[Figure not available: see fulltext.]publishersversionpublishe

Advanced studies of ancient colours to safeguard cultural heritage and new sustainable applications

Funding Information: This research was funded by the Portuguese Science Foundation [Fundação para a Ciência e Tecnologia, Ministério da Educação e da Ciência (FCT/MCTES)], Márcia Vieira [ SFRH/BD/148729/2019 ]; Paula Nabais [ 2021.01344.CEECIND ]; Vanessa Otero [ 2020.00647.CEECIND ]; Projects STEMMA “From singing to writing – survey on material production and routes of Galician-Portuguese Lyric”, PTDC/LLT-EGL/30984/2017 ) and "Polyphenols in Art: chemistry and biology hand in hand with conservation of cultural heritage", PTDC/QUI-OUT/29925/2017; Associate Laboratory for Green Chemistry- LAQV financed by FCT/MCTES ( UIDB/50006/2020 and UIDP/50006/2020 ) and co-financed by the ERDF under the PT2020 Partnership Agreement ( POCI-01-0145-FEDER-007265 ). Publisher Copyright: © 2022 The Author(s)Heritage materials are highly complex systems of unknown and intrinsically heterogeneous compositions and unmonitored long-term modifications. In this microreview, we describe our interdisciplinary approach, its importance to new treatments tailored to prevent changes to historical colours, and innovative strategies for their identification in artworks. We illustrate our methodology through the study of medieval Islamic manuscripts from the Fondo Ka'ti. These advanced studies have shown the remarkable properties of ancient dyes, their resilience and durability, properties designed by our ancestors through sustainable materials processing. This lost knowledge can be shared with the community empowering them to create new sustainable applications, from unique art pieces to regional value-added products.publishersversionpublishe

a review of their degradation mechanisms and conservation treatments

Funding text 1 N. Teixeira thanks FCT for CEECIND/00025/2018/CP1545/CT0009. S. Sequeira and V. Otero acknowledge FCT/MCTES for CEECIND/01474/2018 and 2020.00647.CEECIND, respectively. The authors acknowledge all team members of the project Polyphenols in Art for their helpful and enthusiastic discussions. Funding text 2 This work received financial support from the Portuguese Science Foundation through the projects UID/QUI/50006/2020 (LAQV-REQUIMTE), PTDC/QUI-OUT/29925/2017 (Polyphenols in Art—Chemistry and biology hand in hand with conservation of cultural heritage) and PTDC/LLT-EGL/30984/2017 (STEMMA (“From singing to writing – survey on material production and routes of Galician-Portuguese Lyric”).Iron-gall inks are an essential element of our written cultural heritage that is at risk of a total loss due to degradation. This degradation leads to the loss of the support, particularly the cellulose-based support. Intending to stabilize it, we have come a long way from the nineteenth-century cellulose nitrate laminations to the relatively recent phytate treatments; nevertheless, less invasive treatments are needed. To pave the way for developing safer and more sustainable treatments, tailored as much as possible to the object, this paper reviews the conservation treatments and the advances that have taken place over the last decade in our understanding of the degradation mechanisms of iron-gall inks, based on a careful selection of references to support a concise microreview. This discussion is based on the currently accepted models based on the Fe3+-gallate and the identification of degradation products for iron-gall inks observed in heritage objects, including manuscripts dating from the fourteenth to seventeenth centuries and drawings from the fifteenth to nineteenth centuries. The degradation promoted by iron-gall inks induces scission of cellulose through acid catalysis and/or redox reactions. The causes of these acid-base and redox reactions are also assessed. Finally, we detail the state-of-the-art conservation treatments used to mitigate iron gall ink deterioration, covering treatments from the late nineteenth century to the beginning of the twentieth century, followed by the presentation of current phytate treatments and new postphytate treatments.publishersversionpublishe

The Colors of a Bible and Three Gospels Produced in the Armenian Diaspora

Funding Information: This research was funded by the Portuguese Foundation for Science and Technology [Fundação para a Ciência e Tecnologia, Ministério da Educação e Ciência (FCT/MCTES)], through PhD grants awarded to Márcia Vieira [SFRH/BD/148729/2019] and to Hermine Grigoryan [PD/BD/142866/2018], CEEC junior contract awarded to Paula Nabais (2021.01344.CEECIND), UIDB/EAT/00729/2020, UIDP/00729/2020; Associate Laboratory for Green Chemistry- LAQV financed by FCT/MCTES (UID/QUI/50006/2019 and UIDB/50006/2020) and co-financed by the ERDF under the PT2020 Partnership Agreement (PO-CI-01-0145-FEDER-007265); Glass and Ceramic for the Arts—VICARTE financed by FCT/MCTES (UIDB/00729/2020 and UIDP/00729/2020); Laboratory for Instrumentation, Bio-medical Engineering and Radiation Physics—LIBPhys financed by FCT/MCTES (UIDB/04559/2020 and UIDP/04559/2020). Calouste Gulbenkian Foundation grant on Armenian Studies (No. 269685) awarded to Hermine Grigoryan. Publisher Copyright: © 2023 by the authors.The illuminated manuscripts at the Gulbenkian Museum were produced in the 17th century, in scriptoria of the Armenian diaspora. In this work, we selected analytical methods that can be used in situ to study the colors of the illuminations. Scientific analysis based on fiber-optics reflectance spectroscopy in the visible and Raman spectroscopy has shown the use of a medieval palette based on inorganic pigments such as lapis lazuli, minium, vermilion, orpiment, indigo, two different greens (vergaut and malachite), lead white and carbon black. More importantly, in this context, it showed that the very important reds and pinks are possibly based on carminic acid. The painting technique is, however, different, as are the ways of painting the faces, hands, and vestments. The range of colors in the Bible and the three Gospel Books, enhanced by lapis lazuli blue and organic reds and pinks, demonstrates a desire to create exceptional illuminated manuscripts.publishersversionpublishe

High-order coupling of shear and sonic continua in JET plasmas

A recent model coupling the shear-Alfv\'{e}n and acoustic continua, which depends strongly on the equilibrium shaping and on elongation in particular, is employed to explain the properties of Alfv\'{e}nic activity observed on JET plasmas below but close to the typical frequency of toroidicity-induced Alfv\'{e}n eigenmodes (TAEs). The frequency gaps predicted by the model result from high-order harmonics of the geodesic field-line curvature caused by plasma shaping (as opposed to lower-order toroidicity) and give rise to high-order geodesic acoustic eigenmodes (HOGAEs), their frequency value being close to one-half of the TAEs one. The theoretical predictions of HOGAE frequency and radial location are found to be in fair agreement with measurements in JET experiments, including magnetic, reflectometry and soft x-ray data. The stability of the observed HOGAEs is evaluated with the linear hybrid MHD/drift-kinetic code CASTOR-K, taking into account the energetic-ion populations produced by the NBI and ICRH heating systems. Wave-particle resonances, along with drive/damping mechanisms, are also discussed in order to understand the conditions leading to HOGAEs destabilization in JET plasmas.Comment: 10 pages, 11 figures, accepted for publicatio