The mission of the CRCC's "Tracings" group is to develop characterization of the materiality of the various tracings present on cultural heritage objects, in order to provide a better understanding of their history, their manufacturing process and the evolution over time of the materials of which they are made, in order to contribute to their preservation.
The term "tracings" covers any inscription, sign or symbol present on support materials of various kinds, such as parchment, paper, wood, fabric, stone, etc. These tracings are of interest as part of an overall object, carrying information in their meaning and in their materiality that needs to be documented and preserved.
Tracings, when they present a material input on a support, may have been made using ink, of which there are various types, or pictorial material when the symbols represented have a specific color.
The Tracings group's research focuses on the study of the materiality of these tracings in cultural heritage objects, in order to achieve several objectives:
- revealing and documenting tracings, in particular by obtaining their spatial distribution, in order to find erased or hidden inscriptions, preserve all their components and guarantee the durability of the information they carry;
- identifying materials and techniques used to produce the tracings, and using their composition to contribute to a better understanding of their historical context;
- understanding interactions between the materials composing the tracings and their support, and studying the degradation processes of these materials in order to contribute to their conservation;
- performing methodological development adapted to the constraints associated with these tracings and their support object as a conservation site.
To achieve these objectives, we realize model samples, including the reproduction of ancient recipes of metallo-gallic inks, and we implement various analytical techniques such as X-ray fluorescence, infra-red and Raman spectroscopies. Chemical imaging is also a strong point of the methodology developed in this research, insofar as it reveals the distribution of the compounds identified and therefore plays an important role in the visualization of the tracings studied.
Since the creation of this research group in the CRCC team, in 2021, the permanent agents contributing to this activity are Oulfa Belhadj and Marie Radepont, in collaboration with agents from other groups of the CRCC team as well as from the CRC's two other teams.
1. Chemical imaging of tracings to reveal inscriptions and symbols
Tracings, being inscriptions, drawings, signs or symbols, may no longer be accessible today, either deliberately hidden so as to lose the information they carry (redaction), involuntarily because the support has been reused for its mechanical properties to the detriment of what it carried (palimpsest, fragments in book bindings or as lining in musical instruments), or degraded by the object's use or environmental impact.
Even when they are invisible to the naked eye, imaging techniques can be used to find these tracings. The "Tracings" group is involved in a number of research projects allowing the development of methodology and the implementation of imaging techniques to reveal these lost tracings, such as the use of X-ray fluorescence imaging to reread sheet music stuck to the spine of a book, or to support the rereading of letters from the correspondence between Queen Marie-Antoinette and the Count von Fersen (REX II project).
Among the research projects aiming at using chemical imaging to visualize inscriptions that have been partially erased by use and time, the project on the collection of musical instruments collected by Victor Schoelcher from the musée de la Musique (Paris) shows the importance of recovering information born by these inscriptions in order to place the collection in a precise historical and geographical context.
The pictorial material used in tracings can disappear (loss of cohesion, abrasion) or visually change (physical or chemical transformation), sometimes altering the reading of the drawings and symbols they represent. To rediscover their meaning, the "Tracings" department uses a range of analytical techniques to characterize the original materials used and, in particular, rediscover their distribution and appearance, as in the case of the revelation of lost royal emblems on musical instruments made by Andrea Amati.
2. Identification of the metal-gall inks composition for a better understanding of the historical context of tracings production
Analysis of the materiality of the tracings enables us to identify the chemical composition of the original materials used, which in turn helps us to understand the historical context in which they were produced and to study their preservation, in collaboration with historians, curators and conservators.
In the study of metal-gall inks in particular, the CRCC team has a long experience of these materials, their history, manufacture and evolution. Through physico-chemical analysis, the "Tracings" group gathers information to answer questions raised by their use. Comparing the chemical composition of iron-gall inks from different objects or eras, and in particular the concentrations of metallic elements such as iron, copper and zinc, enables us to group together inscriptions that may be linked by various parameters.
Manuscripts from the Mont Saint-Michel (10th-11th centuries) were a particularly valuable source of material and historical information (EMMA project). In particular, analysis of the inks used in the writings of several of these manuscripts has enabled us to observe a major change in composition between two chronological periods, raising questions about the manufacture of inks and their supply to writing centers.
In a project carried out on wooden tools from Stradivari's workshop in Cremona, from the musée de la Musique collection (Paris), the study of the inks chemical composition raised questions about how to distinguish the authors of different inscriptions.
The study of Merovingian papyri and parchments, and in particular the analysis of the inks used on these different media and according to the type of certificate produced (royal, private, etc.), will also provide an opportunity to place the study of these materials in a particular historical and geographical context (PapMedAn project).