The Film on Film Festival in numbers: how our celebration of celluloid came together

Our ambition for the first BFI Film on Film Festival was to programme a festival exclusively from film prints held in the BFI National Archive, and on the face of it there was plenty to choose from. There are more than 195,000 film prints in the collection, dating back to 1895; from the origin of cinema up to the present. The majority are 35mm film stock, the favoured film format for film distribution until the digital era, but also 16mm, 70mm, 9.5mm and 8mm – both standard and super 8. 

But not all of these are suitable for screening. Where the archive only holds a film print of a title that is core to our collecting policy it is placed in ‘master’ status and placed in our best storage. As every access use is a risk to the print, usage of these materials is limited to preservation work rather than screenings. Other prints were ruled out because of their condition, bearing the scars of their busy lives in previous screenings or succumbing to a variety of conditions caused by the natural ageing of the film – colour fading, shrinkage or the dreaded vinegar syndrome. 

However, there was still a large pool of material to choose from, to which we applied our curatorial expertise and knowledge of collection to extract the best material.

Lists and spreadsheets are an uncomfortably large part of curation. Suggestions from across the archive team were gathered in a shared document to create a longlist to choose from. There were a number of selection factors. Great quality prints of good films were an obvious addition, but rarities and rediscoveries were also important. We had ambitions to ensure nitrate film prints and 70mm were part of the offer, along with a 16mm programme to mark the centenary of this important format. We wanted to ensure that the programme was diverse, had a good mix of international and British titles, and included both features and shorts. The list quickly built to just under 400 titles, the majority of which were picked for inspection by the archive’s Conservation Specialist team. 

An average 35mm feature film is 10,000ft long, which is almost two miles. When a print is booked for projection, it is inspected on a winding bench where a Conservation Specialist will wind each reel by hand, whether a trailer or a two-hour long feature. As they go, they may repair tears or broken perforations, measure shrinkage, redo some splices, add archive leaders and recommend ultrasonic cleaning. They document their findings and update the database for future reference. Many of the titles on our longlist went through this process in preparation for the festival – sometimes more than once if we had multiple copies of a film to compare. 

Films like to be kept in cold and dry conditions to ensure their longevity. All master film materials in the BFI National Archive, and all of our nitrate prints, are kept at a temperature of -5⁰C in our purpose built Master Film Store in Warwickshire. Because of this the film reels have to be gently acclimatised for 24 hours before they can be worked on.

Until 1951 the cinema distribution network was built around flammable cellulose nitrate film prints. Despite the number of obstacles involved, we were determined to screen original nitrate prints at the festival. Given the risk of fire we had to eliminate as far as possible the chance of anything going wrong in the projector, and every splice or repair is a potential weak spot that could cause small jumps in the film gate. We used two key criteria to ensure safe projection, minimal damage and low shrinkage. Only eight prints out of the 80 we inspected passed the tests, of which four are being screened at the festival. 

While 35mm was the principal format for cinema distribution there were periodic efforts to try larger formats to improve image quality and enhance the viewing experience, in particular 70mm film, which is still the preferred choice for filmmakers such as Christopher Nolan and Quentin Tarantino. But it comes at a cost, with a single reel weighing up to 30 kilograms, requiring two technicians to lift it on and off a projector. A film like Lawrence of Arabia (1962) has 13 reels, making storage, transport and handling a serious business. Weight is not the only challenge, and for a few reasons 70mm prints appear particularly prone to colour fading, leading to many of our prints developing a strong magenta bias. In contrast, the excellent colour of our 70mm copy of Ron Howard’s Far and Away (1992) was a key factor in our decision to programme the film at the festival.

The sprockets that carry the film through the projector at 24 frames per second are carefully calibrated to fit the perforations of the controlled standards for 35mm. But as film ages it starts to shrink, both nitrate and the ‘safety’ film stocks that superseded them. Those sprockets can also be thought of as teeth, and if they don’t line up perfectly with the perforation holes, they start to damage the film and risk tears. 0.8% was the maximum amount of shrinkage we would risk for putting a film on a projector, and for some of those prints approaching the borderline this might be their last public outing. 

The BFI Film on Film Festival runs 8 to 11 June 2023.