The Palette of the Medieval North – a non-invasive investigation of the colourants of ten fragments from Medieval Swedish Manuscripts

The palette and constituting materials of several medieval parchment fragments coming from books thought to be locally produced in Sweden have, for the first time, been examined by non-invasive methods for chemical and physical characterization. These books were primarily used in medieval Swedish parish churches (including present-day Finland), and they could be said to represent everyday book culture of the time. Ten fragments from the collections of the National Archives of Sweden dated to the 12th to the 15th century were studied by microscopy, hyperspectral imaging in the visible and ultraviolet range, X-ray fluorescence spectrometry, reflectance spectroscopy in the UV, visible and near-infrared range, external reflectance in the mid- and near-infrared and Raman spectroscopy. Pigments, colourants, and inks have been characterized and identified. The aim was to enhance the understanding of these objects and to evaluate the value of technical analysis, the results of which, when combined with historical and palaeographic studies, will advance the comprehension of medieval Nordic book culture. The results reveal the presence of many of the materials commonly used in book production in Europe at the time, such as vermilion, red lead, azurite, orpiment, and copper-based greens, and also some more unusual substances. The colourant components evince significant variation, and it appears likely that they were largely received via trade routes and learned networks from various European locations. The documents from the 12th century differ from the others in their substances and practices, such as the use of ultramarine for calendar rubrics and the varied use of different reds and greens. There is an unusual use of an iron-based red with copper particles for initials, green earth for initials, organics for highlights, and a probable tannin writing ink with neither iron nor carbon.