About two years ago I was handed a negative and asked what I thought of it. It was from the Prince’s Gate Collection, Berthe Morisot’s Girl Sewing. Its two surfaces were crazed, (fig.1), I found it both wonderful and grotesque but I was deeply smitten.

Acetate Negative
Acetate Negative

My initial interest became more purposeful last year when, together with my colleagues, I realised that we had a problem, the so-called "vinegar syndrome", the result of the deterioration of acetate negatives. Routine processing of photographic orders revealed that some valuable negatives from the 1950s had deteriorated within the past twelve months. For example, negatives from the 1956 survey of Chartres, the 1957 Photographic Survey of Petworth and our Gallery’s Lee Collection photographed in 1958. All of these negatives were totally unusable. Whilst it is possible to replace our Gallery’s negatives by photographing the paintings, photographic trips to Chartres and Petworth would doubtless prove more difficult.

Acetate film often referred to as "safety film", was used predominantly between 1950 and 1970, replacing the less stable nitrate-based film. Polyester eventually replaced acetate. When kept at room temperature acetates have a life of about forty years before the layers of acetate and gelatin separate. We have now reached that time threshold. At first the negative looks quite normal but the pervasive smell of ascetic acid is obvious, hence "vinegar syndrome". Thereafter deterioration accelerates and the familiar crazing develops. When acetate negatives are stored in cool conditions deterioration can be delayed, indeed if kept sub zero they can survive in excess of 3000 years.

An air conditioning unit had been installed in the negative room but the very cool air felt moist. The Relative Humidity (RH) in the negative store had reached levels in excess of 65%, perfect for people but death to negatives. Dehumidifiers were installed to reduce the RH within the acceptable 30%-40%. Through the generous support of the Brindsley Ford family we were able to invest in a digital device to monitor the RH and we have achieved levels of 31% — 35%. Jolly well perfect!

Tests followed to quantify the extent of the deterioration. Most of our pre-1950 negatives are glass and easily identified. It is not so obvious to differentiate acetates from polyesters but a simple test can help determine this. When polyester negatives are placed between two polaroid filters and viewed through transmitted light, colours appear (birefringence, like oil in a puddle). I calculated the Institute ceased to use acetates in 1973. Acetates I considered to be most at risk fall between 1955 and 1969. We have a total of over 22,500 negatives from this period and 550 were selected for testing. Groups of negatives were taken at regular intervals along the shelves, selection was thus both calculated and random. There were negatives of medieval door knockers, marble statuary, Duncan Grant paintings and portrait miniatures. The negatives were placed individually into polythene bags with an A-D Strip (film based deterioration monitor).

The results were alarming, recording levels of up to 100% loss for 1955-1959, dropping to 58% for 1960 and gradually reaching a 100% healthy for 1968.
Everything I have read suggests that the problem will not disappear when we reach the 1960s. If we were to repeat this exercise twelve months hence we could expect the proportion of negatives seriously affected to rise.

What about nitrate negatives? We hold negatives dating from the late 19th century and all literature suggests that any "soft" negative dating before 1940 is almost certainly nitrate. Nitrate negatives deteriorate differently from acetates, the negative becomes brittle and turns brown. Eventually the negatives crack, split and disintegrate. (fig.2) Alarmingly nitrate negatives are purported to self ignite and it is highly recommended that nitrate negatives are stored apart, kept very cool and in fireproof storage. In case I leave you in any doubt, that is to stop the fire getting out not in. A further series of experiments are in progress to calculate our numbers of nitrate negatives. When a slither from a nitrate negative is dropped into trichlororthylene it will sink, acetates will float. The chemical is a bit hazardous to slosh around in the Witt so I opted for "plan B". A slither of nitrate when burned will splutter like a sparkler (firework) whereas acetate will melt. All "soft" negatives tested from the early 1930s have proved to be nitrate.

Nitrate Negative
Nitrate Negative

The problems have made us realise just how rich and unique parts of our negative collection are. We have Conway photographs of early 20th century Russian architecture photographed by Robert Byron. These are tremendously beautiful as photographs and irreplaceable as documents of social history. Many will remember The Golden Road to Samarkand, the exhibition of superb photographs taken by the brothers T.E. and A.W. Lawrence and Robert Byron. I could list many "special collections" of Conway negatives notwithstanding the invaluable archive acquired from our field trips throughout Britain and Europe.

Similarly, the Photographic Survey Department holds a large collection of negatives built up throughout the 20th century, a unique archive representing painting, miniatures and drawings held in private collections throughout England, Wales and Ireland. The survey covers collections both large and small, for the most part unrecorded elsewhere and often unknown outside the owner’s family circle. Collections come and go, they are dispersed and "lost", but we are fortunate in having a record at a point in time. En masse the scope and coverage of the Photographic Survey, is impressive and formidable.

All photographs made from the negative holdings of the Witt and Conway Libraries, Photographic Survey and of our Gallery form part of the unique and enviable study and research tool available to students and staff of the Institute and to scholars and the academic community at large.

How do we preserve the negatives so that material will be available for study throughout the 21st century?

We are well on the way to realising the extent of the problem and we have learned a lot in the past few months but now need to take the "next step". We must separate the nitrate negatives, our oldest and dearest, and move them to a place of greater safety, for them and for us and segregate the deteriorated acetate negatives from the others to prevent the spread of "vinegar syndrome". We need to extend their life by freezing them, giving us time to plan for their future. The cool and dry conditions in our negative store are perfect for healthy negatives as we practice good husbandry in the future. Deterioration under our present conditions will slow down but those affected will last a maximum of 10 years depending on their present age. Refridgeration will buy us time.

Lastly we need to think seriously as to how we preserve and conserve our negatives for practicable use in the long term. Do we digitise the negatives and freeze the originals for perpetuity as objects of desire? Make prints from the negatives whilst we can and discard them when they finally "go"? Replace what negatives we can by photographing original works, in the Gallery for example? All of these options will inevitably incur financial outlay. If we take the route of digitisation we will need to regularly upgrade equipment and carefully manage the collections in their digital negative store.

I recently asked of the British Library if I might visit their negative store. This proved to be difficult because the negatives are stored in a cave in Wiltshire. I feel this is something to aspire to. If anyone has a cave begging with high speed underground links to wc2 please make contact.

BARBARA THOMPSON — Witt Librarian Designate