Care and Handling of Film
Motion picture films are composed of a very thin gelatin emulsion layer coated onto a thin layer of plastic. In older films this plastic base may be the highly flammable cellulose nitrate. Newer film bases, such as cellulose acetate or polyester, are known as `safety’ bases because inhibitors are added to the base during manufacture to prevent the base from burning.
The most common sizes of `safety’ base films are – 8mm, 16mm and 35mm. The gelatin layer contains either minute particles of silver making up black and white images, or layers of colour dyes making the colour images. All of these materials deteriorate in very different ways, but recommendations for their care are mostly the same.
The life of films, no matter what the format or type, primarily depends on the temperature and the humidity at which the film is stored (Vaults). Storage is the most important consideration for your films; they should be in closed – not airtight- containers to protect them from dust and physical damage. Always use clean undamaged containers for storage – even a few rust spots on a metal film container will accelerate the deterioration of the film inside and they must be kept in a dry place with minimum temperature and humidity fluctuations.
Excellent storage for film is a cool dry room (around 15°C-21°C) which maintains stable conditions throughout. Relative humidity must be between 20% - 50%.
Stored films should be wound onto a spool at moderate tension. The tension that a viewing table winds film is probably too tight in most instances. The ideal wind tension is when a film just holds itself together on the spool. Before projection the film should be rewound at a greater tension to prevent the film slipping against itself and causing small scratches. If the film has to be transported, such as through the post, then the film should be wound to the same tension as for projection. This will prevent scratching if it is jostled during transport.
Water is a severe hazard to films and may destroy them completely, so films should be kept well away from places where a leak or overflow of water may occur. Remember that water is not always visible, as high humidity environments mean that there is a lot of water in the air which will accelerate the film’s deterioration, and even allow mould to grow.
Always clean the gate of your projector with a small brush before projecting your film. This should get rid of any hairs or dust which spoils the projected image and cause damage to your film as it passes through the gate.
When handling film always use gloves to avoid touching the emulsion (the dull side of the film) as this is the most easily damaged part and where the image rests.
If at any stage when either projecting or viewing films on the viewing table behaving strangely or making an unusual sound, there is a chance you are causing damage to the film. Stop the activity immediately and check to ensure the film is properly threaded. Regular servicing of equipment will minimise the chances of any mishaps.