New insights into brazilwood lake pigments manufacture through the use of historically accurate reconstructions

Vitorino, Tatiana; Melo, Maria João; Carlyle, Leslie; Otero, Vanessa

doi:10.1179/2047058415y.0000000006

Cited by 35 publications

(50 citation statements)

References 14 publications

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“…This pink pigment lake was applied in backgrounds, clothes, flowers and line-fillers, as an opaque light pink or a translucent carmine. In these cases, the pink pigment was characterised by microspectrofluorimetry as a brazilwood lake, and a very good match was obtained with the historical reconstructions from recipes 9 and 27 from The book how to make colours [53]. The excitation (560 nm) and emission (590 nm) maxima correlate well with the excitation (555 nm) and emission (590-600 nm) maxima representative of brazilwood lake reconstructions, Fig.…”

Section: Sem-eds (Ultralenementioning

confidence: 55%

“…is made with chalk (filled circle), gypsum (filled triangle), protein (filled star) and polysaccharide binder (filled square). The emission and excitation spectra (d) (black line) matches those of recipes 9 and 27 for brazilwood lake pigment from The book how to make colours (gray and dashed lines) [53] Analysis by SEM-EDS of the silver grounds from the red flower bud…”

Section: Sem-eds (Ultralenementioning

confidence: 99%

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Silver paints in medieval manuscripts: a first molecular survey into their degradation

et al. 2018

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The lack of comprehensive studies on silver paints in manuscripts is a handicap to new stabilization strategies and treatments. This work develops and tests a methodological approach for the study of the degradation of silver paints, at the molecular level, using as a case study a French Book of Hours dated from the 15th century from Mafra National Palace collection. In this paper, we show that the global equation commonly used by the cultural heritage community to describe the tarnishing of silver proves to be insufficient to understand the main factor causing its severe and extensive darkening in medieval illuminated manuscripts. This equation depicts the degradation of silver instantly with a sulphide containing species as H 2 S. Recent research has solidly proved that the first intermediate of silver oxidation is Ag 2 O. This theme will be presented in a forthcoming review. Within this framework, we selected four typologies of silver paints, all analysed by in situ techniques and four as microsamples; due to the very small size and fragility of the microsamples, new methods of sample preparation were developed and tested. The main research questions include: (1) understanding how silver-based colour are formed, disclosing its full stratigraphy; (2) define if the other compounds present, such as colour paints and the ground, may affect silver oxidation by stabilizing or accelerating it; (3) comprehend if it is possible to characterize the degradation products of silver paints with the methodology developed in this work, both in the bulk and at the interfaces between layers. Overall our results show that silver-based colours exhibit a complex stratigraphy that impacts its conservation condition. Further research at the molecular level is required on the correlation of the main components of the ground (binder and filler such as gypsum and calcium carbonate) and the paints that are applied as layers over or under the silver leaf. Our case studies have shown that both in situ analytical techniques and scanning electron microscopy with energy dispersive spectroscopy analysis in the microsamples, provide relevant information on the silver colour stratigraphy. However, the information obtained studying cross-sections is more accurate. We consider that the study of the degradation mechanism of silver in medieval illuminated manuscripts will require the combination of both approaches; in situ methodologies support the relevance of the data acquired on the microsamples. Microsamples studies will make possible the acquisition of data that is fundamental to understand the darkening of silver paints and this, in turn, is essential to develop informed and sustainable conservation policies.

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Section: Sem-eds (Ultralenementioning

confidence: 55%

Section: Sem-eds (Ultralenementioning

confidence: 99%

Silver paints in medieval manuscripts: a first molecular survey into their degradation

et al. 2018

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“…It was confirmed (by high-performance liquid chromatography with diode-array detection (HPLC-DAD)) that, in the pigment, the main red chromophore is brazilein [29]. Brazilein is a weak organic acid displaying its first deprotonation at pK a1 of 7 (figure 2), in a water-methanol solution (70 : 30; v : v) [15,30].…”

Section: (B) the Manuscriptsmentioning

confidence: 99%

“…In addition to the analytical tools, it was also important to assemble a database of references for colourants, binders and colour paints [15][16][17][18]. These standards are the result of research into written sources of medieval techniques, which include treatises and recipe books.…”

Section: Introduction (A) the Art Of Colour In Medieval Illuminationsmentioning

confidence: 99%

“…These standards are the result of research into written sources of medieval techniques, which include treatises and recipe books. They are part of reproducing the process described in the source material as well as molecular identification and comparison with the original colours [15][16][17][18][19]. This leads to a virtuous feedback loop, where standard compounds are validated against originals and are used to test and improve the analytical methods applied when identifying those same originals.…”

Section: Introduction (A) the Art Of Colour In Medieval Illuminationsmentioning

confidence: 99%

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