By:
Stuart M. Welch
Managing Director
Conservation By Design Limited

This short paper is intended to present the results of recent experiments and practical applications undertaken by myself and others using vacuum packing and anoxic enclosures with oxygen scavengers for the drying of waterlogged books ( including coated art paper volumes ), photographs and other objects. With the help of Dr. Nicholas Hadgraft this technique was developed when applied to a number of severely water damaged rare books from the Founders Library of the Fitzwilliam Museum in Cambridge.** The system can also be used for humidification with possible applications such as the removal of backings and the re-humidification and subsequent drying of water damaged and distorted items. Vacuum pack drying of wet books taken straight from the deep freeze whilst still icy also produces excellent results.

The principle of drying books, papers or other objects within a vacuum pouch or anoxic enclosure is very simple. Wet material exposed to the normal environment will very quickly begin to grow mould. For this mould to grow it requires oxygen: if we remove the oxygen then the mould will not grow. Taking away the oxygen can be done by:

a) creating a vacuum where all of the air is removed from an enclosure

b) removing the oxygen content ( 21% approx. ) of a given amount of air sealed within an oxygen barrier bag or container.  

Conservation By Design offer the following methods of obtaining a vacuum or an oxygen free environment:

A.       An ArchiPress vacuum packing machine.

B.       A high vacuum pump with an extension hose and a hand held Heat Sealer.

C.       Oxygen scavenger sachets: Mitsubishi Ageless & RP Systemª.

All of the above methods require the use of Oxygen Barrier Bags of varying levels of barrier against oxygen and moisture penetration. New products such as Escalª Ceramic coated transparent barrier films and RP Systemª Oxygen Scavengers which can both control RH and also scavenge pollutant gasses within an enclosure offer enhanced possibilities. Once the oxygen has been removed, and providing that the bag or container does not leak, the wet material will be kept in a state of suspension for many years.

I believe that there is much to discover regarding the preservation and treatment of Museum, Archive and Library collections using anoxic environments and that these techniques will be especially useful for the preservation of Natural History, Ethnographic, Textile, Geological and Modern Media such as Audio, Video, Film, Photographic, Plastic and Rubber collections.

Other applications for drying waterlogged materials such as film negatives, audio and video tapes in a vacuum or anoxic environment have yet to be tried but may also offer a solution to the rescue of this kind of material ( A word of caution: magnetic material cannot be put directly into the vacuum packer because the magnet in the vacuum pump motor may damage the media). 

When used for drying the system requires the use of a highly absorbent material which is sealed inside the barrier bag. The most effective material that I have found so far is Megasorb 100% cotton blotter which is very thick and can be used many times over. However, in an emergency situation I have found that old newspapers will also work. The wet material will share its moisture with the dry material until they reach equilibrium. This process happens very quickly in the vacuum bags and in the case of books and papers has the advantage of holding them in shape. I have also found that this method of drying prevents the blocking normally associated with glossy clay coated papers.

Objects which cannot be subjected to a vacuum can be placed in a bag or air tight container along with the absorbent material and sufficient oxygen scavengers to remove all of the oxygen. With this method it may be necessary to restrain the object to a given form during the drying process to reduce distortion.

As briefly mentioned earlier the reverse of the above process is possible so that objects can be humidified quickly and without the danger of mould growth. For example, I have found that by placing a wet sheet of blotting paper or capillary matting behind an object and then sealing it in a vacuum the water will very quickly be transferred to the dry object until they reach equilibrium. This can be used for the removal of old acidic backings from prints or photographs, humidification prior to vacuum table treatments or the re- humidification of books which may have been damaged by water and have dried out cockled. With regard to the latter it should then be possible to dry them again within the vacuum bags against a restraint board of some kind thus removing the distortions created during the previous drying.N.B. Parchment can also be humidified and dried flat using the vacuum  pack technique.

In addition to the above, experiments conducted by myself and David Jacobs of the British Library have shown that vacuum packing or the removal of oxygen can greatly reduce the   image and colour loss caused by UV light and may also prove to be the ideal storage solution and method of slowing down the process of Iron-gall Ink Corrosion in drawings and manuscripts.

Geological collections are among the most sensitive to oxygen degradation and we owe a lot to the work carried out by Dr. Chris Collins of the Cambridge Geological Conservation Unit and Dr. Caroline Butler of the National Museums and Galleries of Wales. An encouraging and exciting development is the recently formed collaboration between the Geological Conservation Unit of the University of Cambridge, The British Library, The National Museum of Wales and the Tate Gallery London. This resulted in a Conference being hosted by the National Museums and Galleries of Wales which took place on the 29th. & 30th. of November 1999 and which was attended by many international delegates. It is hoped to have a follow up conference when it is felt that there is enough new research work worth sharing.

** See Article by Dr. Hadgraft & Stuart Welch
Paper Conservation News Issue 89 Pages 12 - 14

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Have a look at Owen Bradford, Head of Conservation , Newcastle University and Matthew Parsons, Conservator at the Tyne and Wear Archive's excellent day to day record using the Archipress, for drying water damaged books.

Archipress Vacuum Packing Machine and Polyester Vacuum Pouches