Copy letters using iron gall inks: an historical and physicochemical study for the development of a forensic analytical methodology incorporating both chemical and non-destructive imaging techniques

Kaminari, Agathi Anthoula (2013) Copy letters using iron gall inks: an historical and physicochemical study for the development of a forensic analytical methodology incorporating both chemical and non-destructive imaging techniques. (PhD thesis), Kingston University, .

Abstract

This research is divided in two sections: The first one focuses on original historic documents, namely the copy letters of Heinrich Schliemann. Schliemann, a tradesman, who traveled frequently, but he was also involved in archaeological excavations in several different sites. Therefore, he maintained a thorough correspondence, but also kept a record of it by means of a copy press. Schliemann's outgoing mail extends to 43 volumes and, after careful examination of the entire archive, a selection of pages was studied and documented using nondestructive and hyperspectral imaging methods in the visible, ultraviolet and infrared region of the spectrum. This led to the classification of inks into groups of similar characteristics that can be linked to several factors, among others the inks' recipes. Ultraviolet Reflectance Photography helped in the distinction of the oxidation limits around ink characters. Infrared Reflectography distinguished between oxidation and diffusion of the ink's halo. Visible reflectograms helped to better distinguish the borders of inks. Ultraviolet Fluorescence Colour Photography detected the ink's oxidation halo clearly and more intense than Ultraviot t Fluorescence black and white Photography. False Colour lnfrared imaging differentiated inks based on their false colour in the infrared. In general, the combination of these methods can lead to differentiation of inks compared to each other into groups with similar optical behaviour. The documentation recorded the state of preservation of the document in a specific and given time. The images act as evidence of the actual existence of such an archive and as reference to future comparisons to verify if and when a change has occurred in the state of preservation of the copy letters. As access may be an issue for researchers in faraway lands, the documentation gave direct contact with the images of the archive. It revealed the different inks used during a 50 year timeline, adding helpful information in each era's preferences and availability of writing media. The second section is based on laboratory prepared samples. I n order to understand the copy letters, one has to go through the whole procedure of reproducing them. lron gall ink and copy ink recipes were sourced and used to manufacture inks. The inks were used to write on papers similar to the ones used in the end of the 19th century, and the copy press procedure was applied in order to produce copies. Non-destructive imaging and documentation was applied to the laboratory copies. The resulting images were compared with those of the originals and were able to locate, verify and resolve to the typical characteristics of inks on copies. This is of great importance to historians that come across documents and classfy them, but also to conservators, who need to know if it is a written or copied document in order lo chose the appropriate conservation treatment. The written and copied samples as well as the inks themselves were also analysed using chemical methods of analysis in order to study and to group inks with similar characteristics or differentiate them from each other. The analyses also proved that copied inks retain the characteristics of the original writing, thus making a comparison of copied and non-copied inks directly possible and also making feasible tracing inks back to their original recipe based on their morphology. Scanning Electron Microsopy at high magnifications proved that no matter what was the paper substrate, the morphology of the ink's surface remained the same even when it underwent the copy press procedure or had been transferred onto another paper. Also that inks from different recipes exhibit morphological characteristics that distinguished them in such an extent that can be classified as different. Fiber Optic Reflectance Spectroscsopy revealed that distinction of a copy from a written document is possible and that differentiation of inks can be achieved. Colour measurement of the tristimulous values of each ink led to their classification into groups. Inductively Coupled Plasma spectroscopy revealed much information regarding the ingredients of the paper substrate as well as the ink itself. Raman Microspectroscopy succeeded in proving that the analysed inks were iron gall inks, independently of the paper substrate or the state the ink e.g. before and after the copy press procedure or copy. Fourier Transform Infrared Spectroscopy was performed on be samples depending on their physical phase liquid, solid and ink on paper and showed they can be identified as metal-gall inks. Two of the eight inks can be distinguished from the others. Using Attenuated Total Reflectance mode on inks on paper can indicate differentiation in the recipes. The paper substrate did not interfere in reading the spectra. Differentiation into separate categories could only be achieved by comparison of inks with each other. For a conservator it is very important to be able to classify materials found on objects as it helps in selecting the conservation treatment. Furthermore, inks can be grouped or differentiated due to specific characteristics; this will help historians, archivists and researchers in distinguishing the main text of a document from various additions and if so, also classify the additions based on the type of recipe, in different origins or eras.

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