Watermark imaging forms an important part of Paper Trails, as it is the basis for our research on paper trade as well as for establishing the origin of the paper used in Iceland. There are several methods to capture the images, such as rubbing, tracing and beta radiography. For Paper Trails we used a hyperspectral camera and a heat source, both from the Fraunhofer Institute for Factory Operation and Automation IFF in Magdeburg, Germany.
With infrared and hyperspectral imaging a heat source, such as a heated glass plate or a special light bulb, is placed behind paper, and an image of the heat permeating the paper is then taken. The heat spreads differently through the paper: faster where the paper is thinner, i.e. where the watermark and chain and laid lines are, and more slowly where the paper is thicker. Furthermore, iron gall ink becomes invisible in infrared light above 1,000 nm, which means that distracting writing is eliminated and the watermark and chain and laid lines become clearly visible.
In our project, we used a hyperspectral camera that takes scans in the range of c. 1,000-2,500nm. It has a very narrow band width, scanning every 6nm between 967nm and 2,499nm, which gave us 256 scans for each watermark image. It was quite exciting, looking at the manuscript in front of us, the pages covered in ink and watermarks barely visible, let alone discernible, and then looking at how clearly visible the watermark is on the screen of the camera!
We were able to take nearly 630 scans of more than 480 watermarks from sixteenth- and seventeenth century Icelandic documents and manuscripts. In the following months we will add them to the online watermark database Wasserzeichen-Informationssystem (www.wasserzeichen-online.de), so watch out for them!
The Icelandic National Broadcasting Service, RÚV, found our watermark imaging fascinating, too, and came to interview and film us – we‘ll let you know when it will be broadcast!
The Gerda Henkel Foundation kindly granted us a stipend to cover the costs of the hyperspectral imaging.
Further reading:
https://www.iff.fraunhofer.de www.gerda-henkel-stiftung.de
Meinlschmidt, Peter, Carmen Kämmerer, and Volker Märgner (2010). “Thermographie – ein neuartiges Verfahren zur exakten Abnahme, Identifizierung und digitalen Archivierung von Wasserzeichen in mittelalterlichen und frühneuzeitlichen Papierhandschriften, -zeichnungen und –drucken.” In Kodikologie und Paläographie im digitalen Zeitalter 2, ed. by Franz Fischer, Christiane Fritze and Georg Vogeler. Schriften des Instituts für Dokumentologie und Editorik 3. Norderstedt: Books on Demand, 209–226.
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