Printing plates - Digitization project
The project on printing plates was carried out in the summer of 2024 and involved the digitization and database building of all preserved printing plates at the Language Collections..
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What is a printing plate?
A printing plate, or cliché, is a printing form element for the graphic reproduction of images. Clichés are usually made of copper, zinc, or steel, and are used in relief printing either as halftone clichés/autotypes for reproduction with halftone shades, or line clichés for reproduction without halftone shades.
Originals were photographically transferred to metal plates (i.e. the originals were photographed in a reproduction camera as negatives, see the image below), which were then etched in an acid bath through photochemical techniques for the production of printing plates. Simply put, this means that the negative was copied onto a metal plate covered with a photosensitive coating. The unexposed areas could be removed from the surface, leaving the exposed areas on the plate susceptible to chemical etching using acids (for zinc) or iron(III) chloride solutions (for copper).
Printing plates in the Language Collections
There are a total of 227 printing plates in the collection, depicting either individual manuscripts, charters, maps, or plans. The reproductions of manuscripts in the collection are printing plates that are not mounted on a wooden block. The collection includes the Old Norwegian Homily Book in AM 619 4to from around 1200-1225 in 100 plates and the Oslo City Law in i AM 309 fol. (manuscript h) and AM 305 fol. (manuscript c)/Sth. kgl. bibl. II fol. (manuscript c) from ca. 1300-1450 in 76 plates. The manuscripts were made in connection with the printed edition in Corpus codicum Norvegicorum medii aevi. The edition of the Homily Book was published by Trygve Knudsen in 1952, and the edition of the Oslo City Law by Didrik Arup Seip in 1950. The charter plates in the collection contain 51 plates - all mounted on wooden blocks - from the period 1225 (DN 1:8) to 1383 (DN 1:481), many of which were made in connection with the work of Finn Hødnebø (1960: Norske diplomer til og med år 1300), also printed in the series Corpus codicum Norvegicorum medii aevi. In addition, there is a map of Solum Herred, printed in Lydverket i Solumsmålet. I: Skrifter frå Norsk Målførearkiv (III) by Halvor Dalene (1953), a Lut-letter from 1804 made for May 17th, two gradual plates, and a plan of a ship.
A complete catalog, created by the project leader Juliane Tiemann, will be made available on Marcus.
Project on printing plates
The work in this project involves the following steps:
- Digitization: Photographing the printing plates
- Documentation of metadata: Information about each individual plate
- Accessibility: Integration of collected data into the Special Collections portal Marcus
- Archiving the plates: Repacking in acid-free boxes
Digitization/Photography
Photographing printing plates with halftone nuances is not an easy task. It is almost impossible to capture all the details on the plate, and residual ink, corrosion, or general wear on some plates make it additionally difficult to see what is etched into them. It is often best to see the actual impression when holding the plates in hand and rotating them slightly so that light can hit the plate from different angles. It is also possible to capture more details by adjusting contrast and color afterward, but for this project, we have decided to document the plates as they are. This means photographing them as they appear when lying flat on a table, without the ability to change the angle continuously. This provides an authentic view of how these objects actually look. We managed to capture much of what the plates depict, but a great help to users of the digital catalog is also that most plates were wrapped in paper with a print of the image itself pasted on it, as shown in the picture below.
During the digitization process, we made sure to include everything related to each individual object. After consulting with the archivist Kristin Kjos, we therefore photographed the plates in their packaging (front/back) and then the plate itself (front/back). The photographies were conducted by Morten Heiselberg (Picture Collection) using a light tent and flash lamp (ISO 80, shutter speed 1/60 sec, aperture 17).
Documentation of metadata
To ensure the most comprehensive information about the plates for other researchers and interested people, the project leader has developed a form with defined relevant metadata for documenting this collection. This form is used to gather information about each individual plate and facilitates a detailed description of the material. The collected information includes:
- a) Information about the object: ID, dimensions, weight, condition, metal type, manufacturer, matrix technique, production year
- b) Information about the original object: object type, signature, production year, content information, link to digital publication, comments.
It was not possible to gather all information for every plate (f.ex. the exact production year).
The metadata registration was conducted after the digitization process and concurrently with the repacking of the plates in acid-free boxes, carried out by Juliane Tiemann. To identify the metal type, she received assistance from Odd Erlend Lundsbakken and Hannah Young, archaeological conservators at the University Museum. To determine the materials used in the production of the plates, an X-ray fluorescence spectroscopy (XRF) was performed. XRF spectroscopy is a non-destructive method for measuring the elemental composition of materials with high precision and accuracy. For the analysis of the plate collection, 12 samples were selected (AM 305 fol.-1, AM 619 4to-1, DN 2:103, DN 13:2-1, DN 13:2-7, DN 16:1, DN 2:19, DN 2:40, DN 3:41, plan, map, graduale-2) and measured using a Niton™ XL3t GOLDD+ portable XRF analyzer. The instrument was set to precious metals, with each measurement lasting 30 seconds.
Accessibility of results and related publications
All results from this documentation and digitization project will eventually be available on the Special Collections portal Marcus. We are in the process of uploading high-quality images along with associated metadata for each plate. This will create a new collection in the portal. The information will also be registered in ASTA and Arkivportalen, a task that will be done by Kristin Kjos.
In conjunction with the creation of the collection, Juliane Tiemann has gathered information on the history and production methods of the plates. An article about the collection will be linked to this page as soon as it has been published.
Archiving the plates
The plates in the collection were stored on shelves in the Special Collections depot after the move from the University of Oslo to the University of Bergen. However, the moving process did not involve repackaging the collection, so the plates remained exposed to acid-containing paper packaging in which they were originally packed, or, if they had no packaging, they were stored without any protective wrapping. Through the project, each plate received an acid-free box. The acid-containing packaging for the plates that had been previously wrapped (as shown in the picture above) is stored with the plates, but separated by acid-free paper to prevent further corrosion. All packages were assigned collection numbers and are now stored appropriately in the Special Collections depot.
Future work
We are now planning the next phases for maintenance, during which corrosion damage will be removed from the plates. Additionally, there are plans to use some of the plates for their intended purpose: to reproduce these old prints! The selection of the plates suitable for this will be carried out in collaboration with the conservators and the archivist for the collection.