State initiative for preservation of substance

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Archives before and after processing
Example of damage caused by acidic paper

The State Initiative for Preservation of Substance (LISE) is a partnership initiative of the State of North Rhine-Westphalia with the Regional Association of Westphalia-Lippe and the Regional Association of Rhineland for the deacidification of non-state archive material.


With the rapidly increasing demand for paper since the invention of the printing press and the spread of the written form, there were more and more resource bottlenecks in paper production . Around 1700, alternatives to the rags used up to that point were being sought. Around 1845, Friedrich Gottlob Keller developed the process that is still common today for the industrial production of inexpensive paper using wood pulp . Here, wood is mechanically shredded under water. The resulting fiber pulp contains lignin , which turns into acidic components over time. This causes the paper to become brittle and yellow. In addition, a wood-alum glue (potassium-aluminum-sulfate) is added to the pulp so that it can be written on, which also has a very low pH value . These acid effects lead to a progressive loss of strength and to yellowing of the paper.

Age-resistant papers have also been produced since the 1980s. These are standardized by DIN EN ISO 9706.


In 2005, the State Secretary for Culture, Hans-Heinrich Grosse-Brockhoff, presented the cultural policy of the state government of North Rhine-Westphalia for the 14th electoral period, emphasizing for the first time the preservation of existing buildings as a key issue. The two landscape associations were involved in the planning of state-wide conservation measures from the outset, and the aim was to intensively promote the mass deacidification process in order to preserve as much of the cultural heritage as possible. The cooperation agreement for this was concluded in November 2006 and should initially run until 2010. Due to the collapse of the Cologne City Archives in 2009 , the agreement was prematurely extended to 2015 and expanded to include further conservation measures such as mechanical repairs and cleaning of the Cologne City Archives archives. Most recently, the project was extended to 2019.


According to the cooperation agreement concluded in November 2006, the two landscape associations should sensitize the non-governmental archives to this issue, advise them and support the organization of the deacidification measures by service providers. In addition, the landscape associations take on the work steps of preparing and post-processing the documents to be deacidified. For the Regional Association of Westphalia-Lippe, this takes place in the LWL Archive Office for Westphalia in Münster and for the Regional Association of Rhineland in the Technical Center for Conservation in Pulheim. The deacidification process is carried out by external service providers.

The state of North Rhine-Westphalia bears the costs for equipping the machining centers as well as consumables and personnel costs. Above all, however, the costs for the deacidification of archive material are subsidized. 

Overview map of the participants in the state initiative for maintaining substance in Westphalia-Lippe (as of 2016)
Participation of non-state archives in Westphalia-Lippe 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016
Municipal archives 6th 33 45 48 49 46 56 58 58 63 65
Church archives 1 3 3 3 4th 4th 4th 4th 4th 4th
Private archives 3 1 1 1
Literary archives 2 1
Uniarchive 1 1 1
Political parties 1 1 1 1 1 1 2
Economic Archives 1 1 1 1 1
Foundation archives 1


As a rule, a distinction is made between two key deacidification processes, the single-sheet process and block deacidification. The actual deacidification process involves the least amount of time. Pre- and post-processing as well as transport and planning make up a large part of the project.


Depending on the deacidification method, different measures have to be taken in preparation. Depending on the process, the landscape associations dry cleaning, smoothing and removing metal first. For the block deacidification, protective sheets are also inserted by the service providers in order to prevent certain dyes from staining on opposite sides. The preparations for the single sheet process, on the other hand, are much more complex. All sheets must be smoothed out and adhesions with self-adhesive tapes must be loosened. Water-soluble labels and adhesions that must not be detached are secured with a special restoration tape.


In the case of single sheet deacidification, all sheets must first be foiled. Each sheet is then passed through a deacidifying liquid for 3.5 minutes. The sheets are then dried using a heatable roller. During this drying process, due to moisture, a corrugation occurs on the papers, which is why they are then pressed again by machine to reduce the increase in volume.

During block deacidification, moisture is first removed from the archive material so that it is particularly receptive to the deacidification solution, in which they are then soaked for a few minutes. In the next step, the archival material is dried under vacuum. Finally, there is a reconditioning phase in which the material is supposed to take up the original paper moisture again.

post processing

During post-processing, papers previously removed and not suitable for deacidification (e.g. photographs, maps and plans) are returned to the records, with the alkali-sensitive archive material being wrapped in protective sleeves made of neutral paper. Finally, all documents are examined for completeness and quality of the deacidification measure.


  • Arie Nabrings: State initiative for preservation of substance in North Rhine-Westphalia. A measure to preserve non-governmental archival material . Ed .: VdA - Association of German Archivists eV Volume 13 , 2008, ISBN 978-3-9811618-2-3 .
  • Manfred Anders, Peter Bartsch, Karl Bredereck, Anna Haberditzl: On the chemical strengthening of paper in connection with paper deacidification. (PDF; 4.4 MB) In: IADA Preprints. 1995, pp. 81-85.
  • Reinhard Altenhöner, Agnes Blüher, Andreas Mälck, Elisabeth Niggemann, Antje Pothast, Barbara Schneider-Kempf (eds.): A future for sour paper. Perspectives from archives and libraries after the KUR project "Sustainability of mass deacidification of library goods". Journal of Libraries and Bibliography, special volume 106. Frankfurt am Main: Klostermann 2012
  • Thomas Jaeger: A future for sour paper . In: German National Library (Hrsg.): Dialogue with libraries . tape 2011/1 , 2011 ( ).

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