The article delves into a comprehensive analysis of the writing inks used in historical documents related to the Portuguese Inquisition from 1570 to 1790. Through the utilisation of advanced analytical techniques such as micro-Raman spectroscopy and micro-Fourier transform infrared spectroscopy, the study aims to unravel the mysteries surrounding the iron-gall inks prevalent in these documents. The research reveals significant differences in the colour and texture of the inks, indicating potential variations in composition and sources.
Notably, the presence of Zn-containing inks raises questions about intentional additions or diverse ink origins.
Moreover, the investigation sheds light on the degradation phenomena observed in the documents, ranging from halos around writings to ink migration and paper support loss in heavily inked areas. These degradation issues pose challenges to the conservation of the historical materials, emphasising the need for meticulous preservation strategies. The study also highlights the impact of ink concentration on the colour evolution of writings, showcasing a sequential transition from dark to lighter hues as the ink diminishes.
Furthermore, the research underscores the significance of understanding the chemical composition and degradation patterns of historical inks to preserve and interpret these valuable documents accurately. By providing detailed insights into the ink characteristics and associated degradation phenomena, the study contributes to the broader field of heritage conservation and material analysis.
Overall, the findings offer a holistic perspective on the iron-gall inks used during the Portuguese Inquisition era, enriching our knowledge of historical writing materials and their conservation challenges.
