It is important to know the nature of the material you are dealing with. Some film types, or emulsions, respond differently to treatments or require special processes to achieve the desired outcome. And if a film needs to be duplicated, some emulsions are more suitable for this purpose than others.
The primary concern when handling a film is that no damage should occur to the film as a result of handling. Any equipment used while handling film should be clean and correctly adjusted.
The process of producing a motion film production usually requires many different stages: from original photography and editing to the final release version. The film stock used at each stage is optimised for one particular characteristic, e.g. a release print is designed for projection and is much less suited for duplication.
In managing a collection the purpose of each item needs to be considered from the technical characteristics point of view. For example, it may not be suitable to offer access to the original negative for duplication as the various effects or final colour grading information may not be included, let alone any preservation risk concerns.
The gauge is the width and other physical characteristics of the film itself. The perforation shape and the actual image size can also be indicative of the gauge, e.g. Standard 8mm and Super 8mm.
Fig 10.1 Various film gauges
Films can be categorised by the emulsion type. The emulsion type describes the purpose that the film has been designed for, e.g. a camera negative for original photography where multiple copies will be made.
Fig 10.2 Examples of different film emulsions
Negative materials generally have just the base density around the perforations, whereas reversal materials are black in this area. Colour negatives have an orange base density. This is a masking layer used to improve the performance of the colour dyes.
Intermediate positives/duplicating positives, used for creating copies of negatives, are usually very dark and low in contrast. In colour materials these have the typical orange base colour of the masking layer found in colour negatives.
The perforations are used to transport the film through the cameras, printers and other equipment. Over the years many different types of perforation have been tried and for one reason or another discarded. For example, the early Lumiere films had single round perforations, one pair per frame.
Fig 10.3 Perforation shapes
Perforations not only differ in shape but also the distance that separates them, known as 'perforation pitch’. Continuous contact printers operate with the original film and raw stock in contact passing around a large sprocket. To allow for the increase in the circumference, caused by the thickness of the inner layer of film, the outer layer of film requires a larger perforation pitch. This prevents slippage on the sprocket and results in a steadier image when projected. The difference in the pitch is between 0.2-0.4 per cent. The pitch is also adjusted on 16mm film by a similar amount. All films designed to be used in a camera will have the shorter pitch dimensions and generally duplicating materials will have the longer pitch as will release prints.
Film Duplication and generations
Professional motion picture film production goes through many stages from the camera to the screen. The production chain for image material is usually from negative to positive to negative etc. There are materials that were used for a short time, Colour Reversal Intermediates (CRIs), that could make a direct copy of a negative saving a duplication stage. However, these materials were awkward to control and are no longer used.
In identifying whether a film is an original negative or a duplicate some clues that may help are:
- 'print through’ of edge markings
- camera gate marks
- black framelines (may indicate a CRI)
- additional frame edges
Fig 10.4 General motion picture duplicating process
Opening stuck film cans
Sometimes old or rusty cans can be quite difficult to open. It is often helpful to tilt the can to a vertical position and gently tap the rim of the lid against a hard surface, as you might with the lid of a jar. A variation on this is to hold the can firmly against your side and using the edge of your hand 'chop’ the lid of the can. Another method is to wedge a screwdriver or similar instrument between the lid and the bottom of the can to prise them apart.
Fig 10.5 Film losely packed in the can
Fig 10.6 Film tightly packed in the can
In considering which method to use, the likelihood of damage to the film should be considered. For example, if you think that the film is loosely wound inside the can then any technique that will cause the film to move around is probably not a good choice as it will increase the risk of damage to the film by scratching. Conversely, if the film is very tightly wound and packed into the can then using a screwdriver to prise the lid away may also damage the outer edge of the film.
The primary concern when handling a film is that no damage should occur to the film as a result of handling. To avoid damage:
- Staff should be adequately trained in handling procedures
- All work areas must be clean and free from obstructions that may interfere with any part of the handling operation (books, papers, etc)
- Any equipment used should be clean and in good repair
- The lighting level and quality should be appropriate to the task
- The work room should be reasonably quiet, often it is the senses of touch and hearing that will pick up problems before the problem is visible
The overriding principle of film handling is to not allow the film to move against itself (risk of cinching) or to come in contact with other objects during handling. Gentle movements and close attention are essential at all times.
Cores and reels
A reel of film may contain hundreds or even thousands of feet of film. Usually film is held on a reel or on a core and stored inside a can of some sort. It is common to receive a film that has neither a reel or core and may even not have a can! Consequently, the first stage of any treatment is to ensure that the film can be handled safely and conveniently by placing it on a core or reel.
If the film is not on a core or a reel before it is examined, use some scrap film or cardboard to bush the centre of the film so that the film will fit tightly over the spindle of the winder. Support the film on both sides using winding plates. This will prevent the film from moving around and possibly cinching during the examination.
Fig 10.7 Inserting a protective leader into a film pack that has no core
Gloves and protective clothing
There are many issues around the wearing of gloves when handling films. There are two types of gloves most commonly used for film handling and examination.
Cotton gloves that are thin and open weave are very suitable for general handling of film. Problems can arise if the edges of the film are damaged. The sharp edges of the film can catch on the open weave of the glove and tear the film further especially if the film is being wound.
Surgical gloves are made from thin latex and allow a large degree of 'feel’. The drawback with this style is that after a while they are very hot to wear and can become uncomfortable.
One option is to wear surgical gloves when handling very dirty cans and films, especially decomposing films, and cotton when handling cleaner films.
Whether you are wearing gloves or not you must always keep your fingers away from the image part of the film. Acids and oils from your skin can leave permanent marks on the films surface and any dirt adhering to the gloves can scratch the emulsion.
Other items of protective clothing are outer garments such as laboratory white coats. Mostly these have long sleeves and open cuffs. Cuffs often catch on the handles of film winders and cause the winder to rotate, possibly damaging the film. For preference the cuffs should be tight enough so that they cannot catch, or the coat should have short sleeves. If nothing else is available then rolling up the sleeves can prevent a disaster.
Sturdy footwear is important — if a can of film falls from a bench it can cause injury.
Film winders and winding
To examine, repair or treat film it is important to be able to keep control of the reel and prevent the film from coming into contact with dirt and potentially abrasive surfaces.
The most common method of handling film is to use a set of film winders. And if the film has been stored on a core rather than a reel then plates are also needed to hold the film reel in shape as it is being wound.
Film winders fall into two broad categories. In one, the circular disc against which the film is wound is horizontal, or slightly slanted, like a gramophone turntable, Fig 10.8 i). In the other it is vertical like a vehicle wheel Fig 10.8 ii). Regardless of whether horizontal of vertical winders are used the handles must be counter balanced. Counter balanced handles provide a more even tension to the films wind and allow you to stop winding at any point without gravity pulling down the handles.
Fig 10.8 i) Horizontal winders
Some films are received loosely wound (sometimes of necessity because they are damaged and cannot be wound tightly). In this case, gravity pulls the whole reel down onto the turntable, and the film is less likely to fall of the reel. All the film is near the surface of the winding bench and is easier to manoeuvre.
Most horizontal winders have a low gear ratio between the winding handle and the turntable (commonly 2:1). This gives better control over the wind. Vertical winders are usually geared higher (Commonly only 3:1 or 4:1).
The angle of the wrist and arm required by the horizontal winder also places less physical strain on the operator, compared to that of the vertical winder. However, since the film is further away from the operator there is a tendency to hold a bent over posture for extended periods while examining a film. This can lead to back strain injuries.
ii) Vertical winders
Some operators find it easier to look down through the film, with the plane of the film horizontal rather than slanted.
If it is necessary to wind more than one film (as in synchronising), the vertical arrangement is easier to use as it has a long spindle on which two or more reels of film can be mounted simultaneously.
Film repair is more easily performed on a vertical winder as the slant of the horizontal winder bench can make it difficult to keep the repair equipment in place.
Plates and springlocks
To hold the film in place on the winders and to ensure that the film lies evenly on the core, plates are used. Springlocks hold the plates in place during winding.
Fig 10.9 Plates and springlocks
The plates used for any film should be specific to the film gauge (35mm or 16mm) and to the diameter of the film pack, i.e. 1000 foot plates for films up to 1000 feet long, 2000 foot plates for films between 1000-2000 feet. If the plates are too small the film can spill over the top (Fig 10.10) and become tangled around the winder, causing severe damage. If the plates are too large it can be awkward attaching or removing the adhesive tapes holding the leader.
Fig 10.10 Plate and film pack diameter
For shrunken film it can be useful to have the plates hub slightly modified so that the core fits precisely between the plates. Normally there are a couple of millimeters clearance to prevent the film from catching on the edge of the plate. By modifying the hub the buckled film is more restricted in moving around during winding and a more even wind will result.
Fig 10.11 Modified hub (on right)
It is essential that you remain in complete control of the film at all times. At any time you must be able to stop without the film going everywhere. Always be aware of your winding speed, the angle of film and tension. If the film has no protective leaders at the head and tail then leader should be taped on before examining or winding. The tape should only be applied to the base of the film, never to the emulsion.
The alignment of vertical winders is important. The winders should be initially set up so that the plates are in line. Then the right hand winder should be move about 1-2° clockwise. It is convention to wind film from left to right. If you normally wind from right to left then the left hand winder should be the one adjusted by a similar amount in the anticlockwise direction.
Canting the winder provides a gentle edge to wind the film against. This provides a more even wind with no leafing (layers of film sitting above the film pack and highly susceptible to damage). If the winders are angled too far then the film will twist against the plate and the additional pressure may damage the film.
Fig 10.12 Vertical winder alignment
Winding problem film
If the film is sticky (e.g. from ferrotyping or decomposition) or very brittle, it should be wound slowly and with less tension. This helps to minimise the potential for further loss of emulsion.
If there is a slight tearing or ripping sound while winding stop immediately and examine the film. The film may be blocked and by continuing winding damage will occur to the emulsion.
If the adhesion is only very slight then a small piece of non-abrasive material — such as a piece of folded cardboard or ideally a thin strip of teflon — held at the point where the film lifts away from the pack will help to free the adhesion as the film is unwound very slowly.
Fig 10.13 Lifting lightly adhering film away from the pack