DRAINAGE OF ABSORBABLE OBJECTS

We all know that paper or non-durable materials (fibres, leather, etc.) including valuable documents deteriorate slowly. Paper turns yellow, letters fade and text becomes unreadable over time. Fibres slowly weaken and disintegrate. The most important exhibits (documents, clothing) are of course protected, but there are unforeseen circumstances when, for example as a result of flooding, documents or valuable book collections are flooded and begin to deteriorate rapidly. In such cases it is necessary to act quickly and effectively.

The Faculty of Chemistry has developed a fast and effective method:

• drainage,
• drying,
• disinfection,
• protection against the influence of micro-organisms,

objects made of paper, cardboard and other absorbent substances such as leather, textiles, wood, etc., that have been flooded with water or other aqueous solutions and destroyed by microbiological pathogens (fungi including mould, bacteria).

The idea of the invention and technology was conceived and implemented during the flood of 1997, when it became necessary to rescue the flooded, silted and infected stock (several thousand volumes) of the University Library of the University of Wrocław. Virtually all flooded and affected volumes were not only rescued, but in cooperation with bookbinders, regained new life. The extraordinary effectiveness of this method was also demonstrated during the process of rescuing documents and evidence objects from three district prosecutor’s offices in Wrocław.

The essence of the method consists of the following steps leading to the dehydration, decontamination and protection of flooded and microorganism-damaged absorbent products:

1. Mechanical removal of fungal growth, including mildew (preferably using a moist sponge moistened with e.g. a 2-5% H₂O₂ solution),
2. placing the objects to be rescued, e.g. books, paintings, textiles, etc., in the vacuum chamber and then,
3. exposing these objects to negative pressure between 0,3 and 0,7 bar and temperatures not exceeding 30°C to low-level microwave radiation in the range of 1,5 to 2,5 GHz, while continuing to pump off the steam released, until they are completely dry, and then
4. filling the vacuum chamber at a constant high pressure above 0.7 Bar with the vapours of an easily sublimable substance or a mixture of such substances with biocidal properties and a broad spectrum of activity, such as p-dichlorobenzene, 2-methoxyphenol, 1-hydroxy-2-methoxy-4-allylbenzene, monoterpene alcohol, chroamphenicol, monoterpene alcohol, boric acid, etc., contained in a special heated container with temperature control,
5. leaving the recovered objects in the biocidal gas environment for some time until it has penetrated all areas released by the water,
6. as soon as the gases have penetrated into any free space of the soaking object, the gas is extracted from the chamber two or three times at ambient temperature and then,
7. after reaching a negative pressure in the range of 0,6-0,7 Bar, the set is filled with neutral gas until the pressure in the chamber reaches atmospheric pressure, after which
8. this gas is passed through the chamber until any remaining biocidal gas in the chamber is removed. However, it is beneficial to leave, as a precautionary measure, micro-traces of the biocidal substances in the absorbent capillary structures of the saved objects.