Image caption Mould on badly stored film can eat away and destroy its contents

A record of British life on film could be threatened from an emerging 'disease' which eats away at film.

Home movies on cine film, videos and even TV and film archive can end up covered in fungal mould if they are not stored correctly.

Researchers hope to develop special sensors to detect the mould before it does serious damage.

Gavin Bingley is investigating films stored at the North West Film Archive at Manchester Metropolitan University.

Cinematographic film has a layer of gelatin on its surface. This emulsion layer is where the image is formed but also provides ideal food for fungi like Aspergillus and Penicillium.

If the fungus forms a layer of mould on a film it produces enzymes which allow it to use the film as food and to grow.

So the damage it can cause is irreversible as the mould "eats" the image stored on the film's surface.

While all film is potentially at risk, it is film that has been stored in damp conditions that is most likely to become infected in this way.

Image caption Irreversible mould damage on a 35mm news reel from the 1920s

Mark Bodner is responsible for conservation and preservation of the collections at the North West Film Archive.

"Because we receive donations of films from many sources, of all ages, they have often been stored in damp conditions where fungus has already started to grow."

Growing problem

"It's getting worse. It's a kind of newish thing. I've been here (NWFA) for 23 years. This has really only taken up over the last eight to ten years. What might have been perfect six years ago has now been affected by mould."

"These films are a huge cultural resource. From industrial heritage, travelogues, documentaries, family films, amateur and professional it's very broad. The earliest film we've got is the Lumiere brothers' 1897 Liverpool scenes, " he told BBC News.

Fewer than 100 of 20,000 film reels kept at the North West Film archive are contaminated with fungal mould, so while the problem is relatively rare, if a fungus affects a film badly enough the damage done is irreversible.

"It's a drastic situation. There's nothing we can do about mould unfortunately. It has devastating effects on the image," He told BBC News.

Image caption Damage to a film can sometimes only show up when it is projected.

And fungal mould is not just a problem for non-feature film collections.

Ron Martin is operations manager at the British Film Institute which keeps an archive of British films and television. He is one of the people responsible for safely storing their archive.

"It won't just be home movies. It can affect any type of film. It comes down to how it's been stored.... It's when you come to project it it becomes quite obvious, " he told BBC News.

The BFI uses state-of-the-art storage methods to prevent the problem.

"We go for cold and dry. At the moment, we're building a new film store in Warwickshire that will hold our master film at sub zero temperatures and at around 35% relative humidity," Mr. Martin said.

"In those conditions some spores may survive in a dormant state but if they're dormant they're not eating the film.... It's certainly a big enough threat for us to be building a sub zero and low humidity vault which will cost several million pounds."

Gavin Bingley and colleagues hope to develop more ways to prevent the problem.

"By placing sensor strips in film cans, archivists could identify .... and take recommended action for the storage, safe-handling and treatment of those with living mould."

The research was presented at a meeting of the Society for General Microbiology at the University of Nottingham