By Dr Nicholas Hadgraft and Stuart Welch

First Published: Paper Conservation News,. Number 89, March 1999

Dr. Nicholas Hadgraft	Stuart Welch

In April 1998 I was contacted by the Fitzwilliam Museum in Cambridge for a second opinion about a group of books affected by flood damage and consequent mould. The outcome of this problem may be of interest to any conservator faced with a similar situation.

The initial cause of the difficulty arose from a leaking drainpipe which was well in excess of 100 years old, taking water from a large roof-space to the museum's main drainage. This lead drain had perished and had systematically leaked water into the building for a period of some time. However, at some point the water had evidently transferred itself onto the back edge of some of the shelves and been absorbed by numerous books standing in the upper shelves of one bay of the Founder's Library. The question arose as to how to dry the books, given that they originated from the collection of Lord Fitzwilliam. Fortunately, I had been working with Stuart Welch over several years on the possibility of using vacuum packing for the preservation of waterlogged papers. Stuart had provided me with samples of many wet newspapers stored within a vacuum pack at room temperature. (I still hold one item dated 1995 soaked but still in pristine condition).

I decided to recommend to the museum that we should not act precipitously, but should buy time in the treatment of these books by storing them within a vacuum whilst we determined the best way of treating them and of drying them. I had heard of a number of water damaged books distorted by vacuum freeze drying, and wondered if it was possible to retrieve the wet items by another technology. Stuart had told me that he had carried out a number of experiments with vacuum packing resulting in the successful drying of wet books. With this in mind I advocated that the Fitzwilliam books be vacuum packed to hold them whilst further decisions were taken. Certain books were too large to fit within the chamber of the small vacuum packer, and these were held temporarily in large bags sealed with a criss-cross welder. In these larger bags an oxygen scavenger was included (i.e.Ageless) and a Ageless eye indicator tablet which demonstrated that the oxygen had been removed. Whilst it is understood that some moulds can live in the absence of oxygen, in this case it proved an effective first line defence. A number of badly mould damaged books were removed from the collection and two were sent for vacuum freeze drying whilst others were given to me for vacuum packing and drying with a desiccant (i.e. Megasorb blotting paper and an 'Ageless' oxygen scavenger). The results of this initial test proved that freeze drying inevitably led to the risk of 'freeze burn' with consequent blocking of the gelatine size at the periphery of the leaves. The gentler process of vacuum packing enabled separation of the leaves and reclamation of the object with minimal damage. In many cases wet book after wet book could be returned to the shelf with nothing but light water staining. Over a period of three weeks over seventy wet books were treated using the vacuum packing technique and were returned to the library.

On average, it took about three to four days to dry, clean and stabilise very wet items. Of the seventy severely affected books approaching fifty per cent were recovered to a condition where they could simply be returned to the shelf, and considering the very unfortunate condition which most of them had reached this was no mean achievement. Of the remaining fifty per cent at least thirty five per cent were brought back to a condition where with some paper conservation and attention to board attachments they too could be returned to the shelf. The remaining items were in poor condition given the severity and duration of exposure to water and mould, and being of comparatively little importance to the collection it was thought that after drying boxing and future conservation would be appropriate. The success of the recovery led the Fitzwilliam Museum to approach the University with a view to obtaining the technology, and thereby making it available as an in-house facility. News spread rapidly and demonstrations have taken place at a number of venues.

The photographs show the success of using this technique as opposed to freeze drying. I am not trying to argue that freeze drying does not have its place, and when used on books in large numbers it may be the only realistic option. Freeze drying also produces varying results, for I have heard of text-blocks being very successfully recovered in the immediate aftermath of a flood using the freeze drying technique. In the case of the Fitzwilliam flood it should be remembered that the books had been wet for some time, and their condition had deteriorated significantly. The use of vacuum packing technology allowed us to avoid some of the phenomenon frequently observed in freeze drying e.g. shrinkage of leather and other covering materials, serious distortion of the boards, strain upon the sewing structure leading to disintegration and freeze burn at the fringes of the leaves.

Books of comparable condition are shown, both came from the same area of the affected collection, and both had degraded paper and size with mould activity. The gentleness of the vacuum packing technique is obvious. In the case of the freeze dried books it is clear that the bindings have been severely distorted and the leather cover has shrunk from the edges of the boards. The sewing structure has been so stressed that it is no longer viable. In the case of the vacuum packed book a number of features can be observed. The very wet leather has been dried out with no shrinkage - the tide mark left by the water is clearly visible on the cover. There has been a little movement at the tail/spine edge where the re-backing leather has pulled back. There is a slight buckling of the leather running from the head of the book to the tail of the book about half an inch in on the spine as you look from the lower board face. This was caused by the blotting paper edge within the vacuum pack and could easily be avoided by ensuring that no hard edge rests against the book within the vacuum. It should be pointed out that the books were packed at speed and in great numbers. After drying with the vacuum packing technique it was possible to part the leaves comparatively easily, whereas in the case of the freeze dried book the paper had virtually formed a solid block especially at the edges of the leaves where there was clear evidence of freeze burn. Vacuum packing offers the option that the book can be removed from the drying process at any stage, and if parting the leaves is better before the book has dried out completely this is a realistic option. If a book is removed from the vacuum before it is sufficiently dry it is a small matter to simply reseal it with fresh desiccant (in this case blotting paper) inside the vacuum.

Whilst the volumes from the Fitzwilliam Museum were all of rag paper being of historic significance, it is interesting to note that the vacuum packing technique is particularly efficacious in dealing with some of the more difficult modern paper types. It has for years been recognised that wet coated papers are especially difficult to treat. Using vacuum packing it was possible to take soaking wet coated stock journals with heavy colour printing, and separate them at different stages of the drying process. The explanation for this is, as yet, unknown but was clearly observed in a number of tests.

Books transferred from a blast freezing unit after flooding have also been dried successfully using the vacuum pack drying technique. However, it should be pointed out that frozen books dried in this way do become wet as they thaw and dry out, and it is recognised that this may not always be desirable for obvious reasons (e.g. presence of pigments).

This technology offers the conservator great scope for future development. That which can be dried can also be humidified ! We have yet to discover the full potential of vacuum packing, but with the exclusion of other environmental considerations (e.g. oxygen and mould spores) it is undoubtedly true that the technology can be applied in numerous ways. It is necessary to consider if it is possible to deliver a prescribed humidification within the vacuum packed environment. Controlled humidification levels within a vacuum will deliver the pre-requisite doses of moisture to an object as well as extract it from an object. Within the vacuum there has to be a level of equilibrium, and this is what (in the first instance) gave rise to the idea of a drying process. Stuart Welch initially observed that a wet object (such as a plant stem or leaf) could be safely dried within a vacuum, when resting against a sheet of blotting paper. His inspiration and its practical application, gave rise to the treatment of a vitally important historical collection, and has not only tackled a serious problem in itself but has also allowed us to re-appraise a portable and readily available technology.

It is known that insects can be eradicated by placing items in an anoxic environment. (Published data on this can be found in Nilsen L. Scottish Society for Conservation and Restoration Journal 1998, Vol. 9 No. 4, pp. 20 - 22, see also Burke J. Vapour Barrier Films. WAAC Newsletter 14(2), 1992, pp. 13-17). In this context the vacuum pack provides an ideal format for the treatment of books. Recent experiments with a very severely damp and mould damaged book from the library at Montefiascone and which was heavily infested with live worm suggests that the technique is very effective. It may be possible to use a vacuum technique in the context of pigment consolidation. We know that it can be used to contain bulky materials within a confined space (e.g. where there are large numbers of single sheet archives or records present) saving as much as 40% of shelf space, and we know that it can be used to reduce oxidation damage and storage requirements in the context of newspapers.

Various grades of vacuum packing bags are available, and the cheaper bags may well have a role to play. It is possible to use un-printed newsprint as an absorbent material for drying purposes rather than the more expensive option of high grade blotting paper. For collections of lesser value these options may be appropriate. However, it should be stressed that the cheaper bags are really only intended for shorter term storage because the oxygen barrier level is less permanent . It is important to monitor the vacuum packed books on a regular basis, because movement of the bags and any rough handling can cause a leak to occur. Regular changing of the absorbent material will be required as very wet books are dried, but there is no reason why clean blotting paper cannot be dried and re-used. At a recent conference held in Wales (LISC 1998) Stuart Welch demonstrated the efficiency of the system by soaking some cheap paperbacks and unwanted hardbacks in a bucket of water, and then proceeded to dry them in front of the audience. In a matter of a few minutes it was clear that the process had started to work, and some wet books packed at various days in advance of the meeting were opened demonstrating the different stages of drying.

At this meeting Stuart also commenced an experiment into the effects of packing photographs with a view to discovering whether or not the pack itself would help to prevent light damage. This preliminary work was followed by similar light fading experiments carried out by David Jacobs at the British Library using a Zenon u/v light to test the effectiveness of the pack. David suggested using normal colour photographic prints which are particularly prone to fading. Stuart Welch supplied a number of packs :

1. a number of photographs without packaging were exposed to the light but were masked with strips of archival grey cover paper

 

2. a control which was the same but was not exposed to the light

3. some prints vacuum packed in two types of bags made of different grades of barrier film, and to which were added diagonal masking strips of archival grey cover paper

The exposed photographs were treated with the light for 50 hours at 1,000 lux. The results were as follows :

1. the unpacked photographs exposed to the light exhibited extreme fading and colour change especially those with the blue colour range, the masked areas remained unfaded

2. the control did not change but provided a helpful measure against which to check the other samples

3. (a) ArchiPress bags (made of a five layer barrier film incorporating polyester and polyethylene with an oxygen barrier) - the photographs showed slight fading

(b) BDF 200 film bag which at 25 micron is thinner than the ArchiPress bag but which nonetheless has higher (eight layer) oxygen barrier level - the photographs showed negligible fading

The idea of using the bags to protect photographs for storage led from using the technique to store newspapers which had resisted fading after being exposed to strong sunlight. This is hardly a great surprise because the fading is an oxidation process, and by excluding the oxygen the damage is prevented, any filtering effect by the film is likely to be minimal. David Jacobs proposes to continue with these experiments supported by the British Library, and no doubt there will be further reports of progress. I understand that the BL is also looking into the potential of this storage for modern media such as audio and audio-visual tapes, films etc. Similar work has also been taking place at the Tate Gallery with a view to tackling the problems of exhibiting and storing light sensitive and synthetic material. In particular Kikuko Iwai spent three months experimenting with methods of storing and framing using oxygen scavangers and barrier films.

 

 

The vacuum packing technique for recovering disaster damaged material is a comparatively recent discovery, and Conservation by Design can arrange for an expert to give a presentation, and train in the use of this technology. For the smaller institution faced with a problem, it is possible to attend the scene and lend practical assistance and the hire of equipment. The simplicity of the technology and its comparative portability provides an opportunity to deal with situations which hitherto appeared too daunting for the conservator or librarian to deal with on site. In the case of rare collections the fact that much can be achieved "at home" has considerable implications for security and insurance.

The on-going research work being undertaken by Conservation by Design, backed with the experience at the Fitzwilliam Museum promises much for the future.

For further information please contact Conservation by Design Ltd. on 01234 846300.

Endnotes

1. Nilson L., "Anoxic enclosures and micro-environments in museum storage: creating practical solutions for environmental problems", SSCR Journal, vol 9 no 4, November 1998, pp.20-22
   
   Burke J., "Vapour Barrier films", WAAC Newsletter, vol 9 no 4, 1992, pp.13-17.
   

Also see....

Slideshow of Book Drying After Floods in Prague

Drying & Humidification Using Vacuum Packing & Anoxic Enclosures

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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