Application of FT-IR spectroscopy on incunabula in the "MAGIC Service Center" project
In the context of the "MAGIC Service Center" project, FT-IR (Fourier Transform Infrared) spectroscopy represents an essential tool for the diagnostic analysis and conservation of ancient volumes. This technique allows to identify the chemical components of the materials that make up the paper and any degradation products, providing useful information for planning restoration and conservation interventions.
A. Operating phases of FT-IR analysis on incunabula paper (ATR Mode):
1. Sample preparation:
The first phase of the analysis consists in selecting unprinted portions of the paper, preferably from the margins or non-visible areas, to avoid damaging the texts or illustrations. These samples will be small enough not to compromise the integrity of the incunabulum, but still representative of the original material.
2. Analysis Methodology:
FT-IR spectroscopy will be performed using the attenuated total reflectance (ATR) technique, which allows direct analysis of the sample surface without the need for invasive preparations. The sample is placed in contact with a diamond window of the ATR sensor, through which the infrared beam penetrates only a few micrometers into the material.
3. Analysis Methodology:
FT-IR analysis allows identifying the main molecular vibrations of cellulose, the primary constituent of paper, and any additives such as gelatin, starch or glues used during the manufacturing of the volumes. The characteristic peaks of specific functional groups, such as O-H, C-H and C-O bonds, will provide indications on the state of conservation of the cellulose and on the presence of acidic or oxidizing substances, which accelerate the degradation of the material.
4. Degradation assessment:
One of the main objectives of using FT-IR on incunabula is to identify cellulose degradation products, such as carbonyl groups (ketones, aldehydes and carboxylic acids), which are signs of paper aging. Spectral analysis will allow us to detect the presence of fragmented cellulose chains, loss of crystallinity or oxidations. The peak around 1730 cm^-1, for example, is indicative of oxidation, a phenomenon that degrades the structure of the material.
5. Digital data archiving:
Each incunabulum subjected to FT-IR will be documented in a digital database containing the chemical-physical information detected. This system will allow us to monitor the conditions of the volumes over time, providing a scientific basis for any future interventions. Furthermore, the data collected can be used to create predictive models of degradation, allowing us to adopt preventive measures for other volumes of historical value.
B. Analysis of inks on incunabula by FT-IR spectroscopy (Reflectance Mode):
FT-IR spectroscopy will also be applied to the study of the inks used, in order to characterize their chemical composition and identify any degradation processes. The inks, often based on organic and inorganic pigments such as carbon, iron gall or metallic pigments, will be analyzed directly on the surface of the paper using reflectance techniques (non-destructive), thus avoiding the removal of samples. FT-IR will allow us to identify the characteristic spectral signatures of the inks, including vibrations associated with organic functional groups such as O-H, C-H and C=O, and will allow us to detect any chemical alterations caused by aging or interaction with the environment. In particular, through FT-IR reflectance, it will be possible to distinguish binders and additives such as gum arabic or egg white, often used to fix the pigment to the surface of the paper. The results obtained will be useful for evaluating the storage conditions of the inks.