Documents in danger - a visit to a paper restoration expert

Pests, water and fire are the greatest dangers to historical documents. It doesn't always have to be as spectacular as it was in 2009, when the city archive of Cologne sank into a neighbouring excavation and two people were killed. Large parts of the historical documents sank into the mud and had to be recovered and cleaned laboriously. Surprisingly, some documents survived even months in damp mud.

The restoration workshop of the Frankfurt City Archive is not quite as dramatic. Mould and water damage, along with pests (for example bookworms), are among the main problems that are being fought there. 

If paper becomes damp, mould is not far away. Mould decomposes the paper and makes it brittle. One can see very well from this document that the lower edge had become damp. It shows the typical darker discoloration that occurs with mould. Parts of the page are already broken off. Such a document can no longer be used without further damage. In addition, the spores are a health hazard for the users. In the restoration workshop such documents are cleaned and the paper is stabilized again by additional layers. However, this procedure is very costly and is therefore only used for particularly important documents.

Another serious problem is acidic paper. With the change of paper production and the use of alum instead of glue from bone or skin. Both substances prevent ink from leaking. Alum-containing papers release acids in the aging process, which corrode the cellulose fibres of the paper. It disintegrates. Even the acids contained in the inks can lead to decomposition (ink corrosion). The raw material used in paper production is also decisive - in the past, paper was made with alkaline solutions from rags and was therefore more durable. Paper made from wood was treated with acidic solutions to remove the yellowing substance lignin. Especially such papers are affected by acid corrosion. The neutralization and removal of the acids is complex. In addition, the paper must then be reinforced with new fibres (fraying).

Thanks to the institute for town history we had the chance to visit this workshop. Here is a link to a short film about this visit:
A visit to the restoration workshop in Frankfurt