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" Identity and Connections Within Medieval Heritage: "
Nabais, Paula Sofia Fonseca
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Latin Dissertation
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| Language of Document
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English
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| Record Number
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1105930
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TLpq2350122031
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| Main Entry
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Nabais, Paula Sofia Fonseca
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| Title & Author
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Identity and Connections Within Medieval Heritage:\ Nabais, Paula Sofia Fonseca
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| College
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Universidade NOVA de Lisboa (Portugal)
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| Date
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2019
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| student score
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2019
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| Degree
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Ph.D.
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| Page No
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298
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| Abstract
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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.
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Analytical chemistry
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Art history
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