EQUIPMENT AND TECHNIQUE

Having dealt with the factors relevant to processing both reversal and negative movie film, we are now able to consider in a little more detail the actual steps involved should the amateur wish to carry out this work for himself.

First and foremost, comes suitable equipment. Short lengths of film can be handled, it is true, in dishes or jugs, but it is generally impracticable to use these for full-sized rolls of movie film. Movie film is, after all, an expensive item in the amateur film worker's budget, and it would be foolish indeed to risk spoiling a roll merely for the sake of saving a few shillings in processing charges.


Types of Equipment

The amateur craftsman will have no great difficulty in making a simple frame for holding the film during treatment in the various solutions, and such items of equipment have been described from time to time in the photographic literature. For those who prefer to buy their equipment ready made, however, there are small, stainless steel or plastic frames and drums to take all reasonable lengths of film. The method of using these frames and drums is perfectly straightforward, although, naturally, if a commercial article is to be considered, then the instructions issued by the makers should be carefully followed.

In the limited space available in this book, it is obviously impossible to do more than outline the general routine that the amateur worker may be expected to follow in processing his own movie films. The suggestion that follow must be interpreted in this light and due allowance made where the conditions of working are not the same. Furthermore, the choice of processing solutions must depend on the type of film to be processed, and here again it would be wise to abide by the manufacturers' recommendations.


Film Processing Equipment

Operating a skeleton type processing drum. The photograph is from K L Briggs Ltd Skeleton type drum processing machine for 16mm film. This model holds up to 100 feet, or 30m of film. The processing trough hold 60 oz. or 1700 cc of solution. construction is of nickel plated brass to resist chemical attack A loading bar, seen attached to the ront of the machine, is provided to hold the spool during threading of the film on to the drum. The drum was made by K L Briggs Precision Equipment Ltd. from Hove in Sussex.

A frame type drier for up to 100 feet (30m) of 16mmm film. A special device is provided to allow for shrinkage of the film during drying.A simple frames shown below.


The flat shape allows it to be processed in a flat dish requiring from 15 to 20 oz of solution only. Two models were available, one to take up to 25 feet, 7.5m of 16mm film in a 12in x 10in (300mm x 250mm) dish, the other up to 20 feet (6m) of 16mm film in a 10in x 8in (300mm x 250mm) dish.

A spiral wire type of drum processing machine is shown below. It is was made from stainless steel or plastic materials. Three models were available. these were:P9 for up to 35feet of 9.5mm filmP16 for up to 26 feet of 16mm filmP35 for up to 12 feet of 35mm film. Normally hand tuned an electric motor, as shown, was also available.


Using a Drum

Assuming that the darkroom arrangements are reasonably adequate, and that efficient safe lighting and access to clean (preferably running) water are provided, we can begin our routine as follows :

1 With the room in pan (dark green) safe lighting, take out the spool of exposed film (or unload it from the charger), and attach the free end to the drum, usually by tucking it under a clip. Make sure, when doing this, that the emulsion side of the film is uppermost on the drum, i.e. facing you, and if in doubt on this most important point, place the end of the film between your lips. The emulsion side is that which sticks to the lip. Be very careful to handle the extreme end of the film only, and avoid touching the emulsion side with your fingers.

2 Now begin to rotate the drum slowly to let it take up all the film. This it should do easily, but it is sometimes recommended that the tank, in which the drum turns, should hold plain water, at the correct temperature, since this helps to hold the turns of film to the drum right from the start. Continue turning until all the film is wound on and either leave the end free or attach it by means of a piece of elastic and a hook to the appropriate point on the drum, depending on the particular instructions issued with the equipment.
3 If there was no water in the tank during the loading of the drum, a sufficient quantity should now be added and the film given a thorough pre-soak by rotating the drum for a period of about two minutes. Speed of rotation is not very important, but for this, and for all other operations in the sequence, you should adopt a general practice of keeping to about 40 turns per minute. The object of the pre-soak is, of course, to avoid uneven development that would almost certainly result without it.
4 Drain the water from the tank and replace the stopper (or close the outlet).
5 Still in pan safe lighting, pour the developing solution (previously placed in a known position and brought to the correct temperature) into the tank as quickly as you can without splashing. Start the timing clock as you do so and keep the drum rotating all the while. Continue turning until the required development time has been completed and then pour the developer into a jug.
6  The next step depends on whether you are handling negative or reversal film. With negative film a brief rinse in water is all that is required, followed up with a fixing solution in the tank. If you are dealing with reversal film, however, the next step is to pour in the hardening solution and reset the clock.
7  After the required time for hardening, pour away the solution and replace it with plain water. Rotate the drum for a few minutes and then empty the tank.
8  Pour the bleaching solution into the tank and start the clock. After five minutes' treatment, it is fairly safe to switch on a subdued white light and you can then watch the further progress of the bleach. Continue the treatment until the film appears as a creamy white all over. Return the solution to the bottle (it can be used again) and fill the tank with water.
9  After a quick rinse, throw away the water and pour in the clearing solution. The yellow stain is usually completely removed within a very short time, but it is wise to continue the action for some two to three minutes.
10 Drain off the solution (it can be used again) and pour in plain water for a short rinse.
11 The second exposure is now given. A few minutes' exposure to the normal white light of the darkroom, if this is strong enough, may be adequate. Alternatively, a Photoflood lamp may be plugged in and the drum held at a distance of about 3 ft. from it for a period of one minute, and rotated very quickly the while to ensure even action of the light.
12 Still in the white light, pour into the tank the developer which you saved in the jug (step 5), and reset the clock. Alternatively, use as second developer the one specially recommended for the film in question. Continue rotation of the drum for the specified time and then discard the developer.
13 Pour in plain water for a short rinse, and then replace with the fixing solution.
14 After fixation, wash the film on the drum in at least six changes of water.
15 Finally, the drying process. If the film is to be dried on the drum, it is a good thing to give it a final rinse in water to which a few drops of wetting agent have been added. This will greatly facilitate draining the water from the film. Alternatively, the film may be wound, while still wet, on to a simple drying frame, in which case it may be passed through a damp chamois leather held lightly in one hand. Drying should, of course, be carried out in a dust free atmosphere, and on no account should any attempt be made to speed up drying by raising the air temperature unduly.
16 When the film is perfectly dry, and not before, it may be spooled up by gently rotating the drum, or drying frame, as the slack is taken up on the spool.

The above description of the various steps involved in processing a length of movie film is necessarily sketchy, and it cannot be over emphasised that all the preliminary work, such as making up the solutions, etc., should be carefully carried out and a simple system of operation adopted.


Test Strips

Before attempting to undertake the processing of a complete roll of exposed movie film, an initial test with a suitable test strip is strongly recommended. This test strip may be a short length broken from the beginning or end of the roll, or it may be exposed specially for the purpose, care being taken in so doing that the exposure given shall be generally similar to that received by the roll, or rolls, to be processed.

The test strip may be developed on the drum machine or, if preferred, in a dish or jug, or better still, a suitably stoppered length of glass tubing of bore to suit the film gauge. Whichever technique is used, it is important to match as closely as possible the actual conditions that the full roll will have to undergo on the machine. Thus, the make-up and temperature of solutions, the rate of agitation and so on - all these must be made to match the normal machine conditions. Obviously, it is safer to develop the test strip on the machine itself, but with a little experience the simpler expedient of dish or jug will be found to give quite satisfactory results.


Taking the test strip as your guide, it should be a relatively straightforward matter to decide on the time of development to give your full roll. If the issue is still in doubt, however, the test should be repeated with a development time more likely to give the desired result.


Providing that steps can be taken to control the second exposure adequately it is not impossible to ascertain, by means of test strips, the extent by which it should be varied from the normal in order to give some degree of compensation for serious over- or under-exposure. Obviously, in the simple technique with which we are concerned in this book, such compensation would inevitably apply to the whole reel being developed so that its usefulness would be restricted to cases where it is known beforehand that the reel is uniformly over or under-exposed.


Anti-Halo Backing

With some types of reversal film the anti-halo backing is located between the emulsion and the base, in which case it will be completely removed by the bleach bath. The Gevaert films are of this type.

With other types, notably Kodak reversal film, the anti-halo coating is on the back of the film, and contact with the drum surface may make complete removal a little more difficult. The best way to overcome the difficulty is to wipe the back of the film while still on the drum with a small pad of cotton wool, immediately after hardening or during the bleaching operation. To do this without damaging the film, simply insert the pad of cotton wool under the free end of the film and hold it in one hand while slowly turning the drum with the other.


Handling Positive Film

Processing positive film presents less of a problem than negative film since it is perfectly safe to handle it in the normal orange light used with bromide enlarging papers. The steps to be followed are the same as those described for negative film, i.e. up to step 6, with the obvious exception that a positive type developer should be used at step 5. Since there is no form of anti-halo coating on positive film, no special action is called for in this respect

Some Common Troubles


Until you gain experience in processing your own films, it is more than likely that you will experience one or more of the troubles listed below. Should you do so, make a point of seeking out the cause of the fault at once. You will thus greatly reduce the risk of it happening again.

Picture too light                First development too long, or second development too short.   Developer old or exhausted.
Picture too dark                First development too short, or second development too long.
Developer at fault.            Over development in second developer
Yellow stain                       Bleaching incomplete or clearing bath at fault.
Blisters or reticulation        Solutions used at too high a temperature, or too great a difference in temperature between the various baths and the wash water.
Bleaching too slow             Bath exhausted or acid content too low.
Streaky picture                   Rate of drum rotation too slow.
Buckling of the film             If a wetting agent has not been used these are usually due to droplets of water left to dry on the film by insufficient squeegeeing. They may also be due to oil on the film.
Buckling of the film             If the film is unduly strained during processing, it may dry in a buckled condition and so give rise to trouble in projection. Check that the tension on the drum is not too great, especially during the drying period when the film will tend to shrink. Buckling may also be due to too rapid drying by excessive heat.
Negative density wrong.     On negative film, too thin a picture may be due to under, or faulty, development (or underexposure in the camera.) Too heavy a picture may be due to over development (or over-exposure in the camera).