Micro‐Raman study of Medieval Cistercian 12–13th century manuscripts: Santa Maria de Alcobaça, Portugal

Abstract

Santa Maria de Alcobaça Monastery, a Cistercian monastery, was established in 1153, in the year of St. Bernard of Clairvaux's death. From the approximately 160 illuminated manuscripts produced during the late 12th to early 13th centuries, a set of 15 manuscripts was selected to characterize the medieval colour palette of this scriptorium, following an interdisciplinary study on Portuguese medieval illumination. Colour paints were fully characterized by Raman microscopy (RM), alongside m-Fourier Transform Infrared Spectroscopy and m-Energy dispersive X-ray fluorescence.The Alcobaça collection shows consistently the use of pink and grey paints, mostly achieved by mixing vermilion and/or an organic red, or a carbon-based black pigment with lead white, respectively. Lazurite was the chosen pigment for blue, being ubiquitous in the studied collection. Azurite was found in the lettering of only one manuscript (Alc. 433). Green is defined as bottle green, commonly seen in Portuguese medieval manuscripts, evidencing the loss of cohesion and adhesion to the support. RM and m-Fourier Transform Infrared Spectroscopy identify a copper complex with a protein, possibly verdigris based. The remaining colour palette comprises orpiment, red lead and two organic dyes (with yellow and dark red) not yet characterised. Darkening is observed for lead white in two manuscripts (Alc. 249 and Alc. 446). RM shows galena, a lead sulfide, as the degradation product of lead white, and a band at approximately 810 cm À1 , indicating the presence of an arsenatebased species. On Alc. 446, an intense broad band at approximately 339 cm À1 was also identified, most likely due to an orpiment-based solid phase in agreement with the reduction of orpiment or the arsenate-based species. A set of experiments was designed to assess the influence of orpiment on lead white degradation, corroborating the previous results and indicating the appearance of a new lead carbonate phase.

Organic dyes in illuminated manuscripts: a unique cultural and historic record

“…SERS analysis was performed after deposition of 0.8 µl of the Ag colloid and 0.1 µl of 0.5 mol l −1 KNO 3 aqueous solution onto each microsample. All spectra were collected by focusing the laser beam onto the microaggregates that formed inside the dye-colloid droplet a few seconds after the deposition of the Ag nanoparticles and KNO 3 . Spectra were acquired continuously until the droplet dried out.…”

“…Over the past 10 years, we have contributed to the development of advanced techniques that allow us to characterize and rigorously quantify colour and colour loss in monastic manuscripts from the twelfth and thirteenth centuries [1][2][3][4]. More recently, these studies have also included books of hours as well as other artworks covering a period from the twelfth to the nineteenth centuries [5][6][7][8].…”

Crocoite PbCrO4 and mimetite Pb5(AsO4)3Cl: rare minerals in highly degraded mediaeval murals in Northern Bohemia

“…The process of alteration of lead pigments in the presence of orpiment has been already observed in mediaeval illuminated manuscripts and described by model experiments. [10,41] Both minium and lead white, respectively, tend to darken in aqueous suspensions with orpiment under normal laboratory conditions as a result of the formation of black galena (PbS), while orpiment is transformed to arsenolite (As 2 O 3 ). The formation of low amounts of arsenates was also corroborated by gradual increase of Raman band at 810 cm À1 , but the arsenates have never become dominant, even after 1-year-long experiment.…”

“…This typical palette has been identified, e.g. in Cistercian 12th-13th century manuscripts in Portugal [10] as well as in the early 12th century manuscript 'Liber Floridus' stored in the Ghent University Library, Belgium. [11] The same palette appeared also in Pre-Romanesque, Romanesque, and Early Gothic wall paintings, e.g.…”

Raman Spectroscopy of cultural heritage Materials: Overview of Applications and New Frontiers in Instrumentation, Sampling Modalities, and Data Processing

“…The firstever reported study focused on the investigation of pigments on illuminated manuscripts [151], and ancient manuscripts have continued to be an area of intense investigation from the early days until the present, where, with XRF, fibre optic reflectance spectroscopy (FORS) [4,259,260], hyperspectral imaging and SERS [5], Raman spectroscopy has become an indispensable tool for the materials knowledge of these important objects [3,47,213,292]. Published studies have not only concerned themselves with the investigation of the palette of illuminated manuscripts and assist with attribution to specific workshops [69] but they also now comprise the characterisation of degradation phenomena including, for example, the chemical and chromatic alteration of pigments based on copper [1,2] and lead [205,285].…”