The problem of ‘Extinguished letters’ and the use of chemical reagents on manuscripts (1551–1553)

The examination of unknown sources reveals that by the end of the fifteenth and the beginning of the sixteenth century, there was a widespread awareness in Italy of the damage produced by the passing of time on books and manuscripts. The expression used to describe such cases was lettere svanite or caduche, which indicated that the writing had faded and was almost unreadable, and, as such, hard to transcribe, indicating that the manuscript needed to be preserved from further damage. Already between 1550 and 1552, in Rome and Venice, some ecclesiastics of the Roman Curia attempted to brighten ancient writing, using vegetable distillate high in tannin. In two cases, it is possible to identify manuscripts processed with this method and to determine the preservation formula as well as an accurate description of each step of the method. The process, now brought back to light, anticipates the chemical experimentations by the Benedictines of St Maur and other techniques, widespread in the eighteenth century, and their basic chemical principle, namely the application of tannin. However, the earlier technique is paradoxically much more complicated than the one applied two centuries later.