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The first 55 years of cinema history was written on cellulose nitrate film. Nitrate is notorious for its flammability, with many fires in cinemas, laboratories, studios and archives as testament to its incendiary characteristics. This chemically unstable compound is also prone to decomposition, causing the images it contains to literally melt away, making it a serious responsibility for a film archive to have it in its custody.
But far from being just a burden, nitrate film is an enormous blessing, an invaluable repository of the past that more than justifies the care, investment and passion dedicated to its survival. What's more, looking after nitrate film elements is crucial for preserving our film heritage. The high quality of many recent restorations - such as Powell and Pressburger's The Red Shoes (1948) and Anthony Asquith's Underground (1928) - was only possible with access to the nitrate materials held in the BFI National Archive. Nitrate gives us the opportunity to get closest to the original elements created for films made before around 1951 - to achieve the best possible picture, we want to avoid materials that have been repeatedly duplicated.
The origins of nitrate film lie in the mid-19th century, when scientists experimented with combinations of naturally occurring substances in order to produce new synthetic materials. The mixing of cellulose fibres such as cotton or paper with nitric acid led to two discoveries. First was a new explosive, known as 'guncotton', which was used for the military and mining but ultimately proved of limited use. Second, solid forms of nitrocellulose were developed that could be moulded and shaped into a variety of forms such as combs, cutlery handles, ping-pong balls, dolls, collars and cuffs. But the most important property of these solid forms was their ability to be rendered into thin, flexible, transparent sheets, which were soon taken up as a replacement for glass plates in photography. Once rolls of film were being produced by the late 1880s, one of the key ingredients for motion picture photography was in place. All of these developments, however, shared the volatility that ultimately led to the demise of nitrate film.
There are, in fact, strong arguments for the technical superiority of nitrate film over the 'safety' stocks, such as cellulose acetate and now polyester, that replaced it. Nitrate emulsion has a higher silver content than any film stock produced after its manufacture ceased in 1951, which allowed cinematographers to create a greater range of greys and perfect, intense blacks. The moody atmosphere of Brighton Rock (1947) is a perfect example of modelling light and shadow on film that fully shows the potential of nitrate film. Later safety prints fall far short of what cinemagoers would have seen in 1947.
When colour is added by hand painting, stencilling or tinting and toning, as was common in the silent era, the vibrancy of the dyes used brings a magical extra dimension to the frames. Current colour duplication film stocks are unable to capture the colour saturation achieved by these methods.
But all this wonderful chemistry has a price. Not unlike the patina of a bronze, nitrate film can undergo a chemical transformation that affects the way it looks. Spots, halos, and ghostly figures can appear on the image as decomposition advances. Other films disappear under a curtain of spiky mould. Kept in the right conditions, nitrate has a long life ahead of it. To preserve the flexibility of the film base or the vivid colours on the emulsion, nitrate has to be kept at the right temperature and relative humidity in closely monitored vaults.
The beauty of nitrate is usually revealed to the public after a process of physical restoration of the film source. We enjoy it through new 35mm prints on polyester stock, Digital Cinema Packages, or DVDs, but these cannot capture the real experience of watching nitrate on screen. As the BFI National Archive celebrates its 75th anniversary, we present rare opportunity to see nitrate projected in all its glory, at a series of screenings at the BFI Southbank. These prints are unrestored, and bear some of the marks and scars of previous screenings. But as digital developments threaten to put an end to production and distribution of films on 'film' of any kind, they serve as an important reminder. More than just carriers of visual information, these prints are themselves artefacts, playing a vital part in the texture, meaning, and reception of the cinema experience. The BFI's nitrate collection is a treasured possession which is very much part of the past, present and future of British film.
Sonia Genaitay, Fiction Curator, BFI National Archive
