Parchments and coloring materials in two IXth century manuscripts: On-site non-invasive multi-techniques investigation

Yacine Oubelkacem; Taibi Lamhasni; Abdelmajid El Bakkali; Saadia Ait Lyazidi; Mustapha Haddad; Abdelouahed Ben-Ncer

doi:10.1016/j.saa.2020.119093

Parchments and coloring materials in two IXth century manuscripts: On-site non-invasive multi-techniques investigation

Spectrochim Acta A Mol Biomol Spectrosc. 2021 Feb 15:247:119093. doi: 10.1016/j.saa.2020.119093. Epub 2020 Oct 16.

Authors

Yacine Oubelkacem¹, Taibi Lamhasni², Abdelmajid El Bakkali¹, Saadia Ait Lyazidi³, Mustapha Haddad¹, Abdelouahed Ben-Ncer⁴

Affiliations

¹ Laboratoire de Spectrométrie des Matériaux et Archéomatériaux (LASMAR), Université Moulay Ismail, Faculté des Sciences, Zitoune BP 11201, 50000 Meknès, Morocco.
² Laboratoire de Spectrométrie des Matériaux et Archéomatériaux (LASMAR), Université Moulay Ismail, Faculté des Sciences, Zitoune BP 11201, 50000 Meknès, Morocco; Institut National des Sciences de l'Archéologie et du Patrimoine (INSAP), BP 6828, Madinat Al Irfane, Avenue Allal El Fassi, Angle rues 5 et 7, Rabat-Instituts, Morocco.
³ Laboratoire de Spectrométrie des Matériaux et Archéomatériaux (LASMAR), Université Moulay Ismail, Faculté des Sciences, Zitoune BP 11201, 50000 Meknès, Morocco. Electronic address: s.aitlyazidi@umi.ac.ma.
⁴ Institut National des Sciences de l'Archéologie et du Patrimoine (INSAP), BP 6828, Madinat Al Irfane, Avenue Allal El Fassi, Angle rues 5 et 7, Rabat-Instituts, Morocco.

PMID: 33137628
DOI: 10.1016/j.saa.2020.119093

Abstract

One among the most famous ancient parchments in the Islamic world, dating back to the IXth century, along with another contemporary one have been investigated by means of a completely non-invasive multi-techniques analysis combining all of elemental XRF and structural/molecular Raman, ATR-FTIR and FOR spectroscopies besides pHs and colorimetric measurements. The materials initially used in the preparation of the writing supports were identified; in addition to calcite at different extents, the parchments seem to be condensed tannins-pretreated. Furthermore, the exploration of amide I and II vibrational bands and sub-bands illustrated collagen gelatinization and molecular helix disorders phenomena. Parchments and inks degradation products, gypsum and calcium oxalates, have been also identified. In both manuscripts the writing black inks have been characterized as iron gall type. The corrosive effect of these black inks appears deeply damaging the acidic parchment supports. In this case, the high frequency side of the infrared spectrum disappears completely, illustrating thus irreversible parchment degradations. Gum Arabic, when added sufficiently in the black ink recipe, seems preventing the corrosive damaging effect induced by Fe²⁺ ions spreading from the black ink into the parchment body. Besides, all coloring materials have been identified; gold in gilded scriptures and natural pigments for vocalizations and basic decorations: cinnabar for reds, lapis-lazuli for blue and orpiment/realgar/pararealgar arsenic sulfides for yellow/orange shades. The anthraquinone-based kermesic acid extracted from Kermes female insects had been used for dark pink decorations, while the copper-based pigment verdigris had been synthetized to achieve green motifs. These results enrich the knowledge of ancient writing supports and materials, and highlight technologies and practices developed by middle-ages craftsmen.

Keywords: Degradation; Elemental/structural/molecular analysis; Inks; Parchments; Pigments and dyes.