Cine Film Processing

A home made device for unloading two super 8 cartridges by transferring the film to 8mm spools. It is much easier to load the spiral of a cine developing tank from the spool.

Obviously this has to be carried out in darkeness. The author managed it in a large changing bag, and then loaded the two films onto the spirals in the same bag.

Tricky, but it worked and no film was fogged.
8mm film on the spiral of a cine developing tank.
A deveoping frame to allow cine film to be developed in a standard developing dish.

This is from an old book but it does not look a difficult device to make from readily available plastic tube and strip.
A developing frame with its tank. Operation is pretty obvious and could certainly cope with a longer length of film than the frame.

Unless in a container with light tight arm access it requires the use of a dark room.

It lloks the sort of device that could form the basis of a home made device.
The Todd tank where the film is wrapped around a drum for processing in a similar manner to the frame. I believe this was a commercial device.
The book from which the above photographs were taken along with  the following processing procedures.
NEGATIVE/POSITIVE versus REVERSAL

Before describing in detail the steps involved in processing movie films, it will be as well to make quite clear the essential difference that exists between the two methods of producing a positive suitable for projection.

The so-called reversal method is the one generally favoured by amateurs since, without any extra cost to themselves on development this gives a positive directly from the film loaded into the camera. This result is achieved by using a special type of emulsion which, when subjected to suitable chemical treatment, forms first a negative and then a positive image on one and the same strip of film. Films coated with this type of emulsion are referred to as Reversal Films and, generally speaking, they do not lend themselves satisfactorily for use as negative films.
Negative film is used in the Negative/Positive method which is akin to the technique of producing prints familiar to all still photographic workers. The film exposed in the camera carries an emulsion similar to that found on ordinary (panchromatic) roll films and, like a roll film, is developed to a negative. The negative is then printed in contact with a roll of positive film to produce a finished print suitable for projection.

Both methods of producing positives have their advantages and disadvantages, but unless more than one copy of the final result is required, the amateur is strongly advised to stick to reversal film. Even if extra copies are required, they can still be made without too much bother from this one reversal positive. Furthermore, as will be pointed out in the next section, reversal film may be expected to have a greater latitude in exposure, and a somewhat finer grain than the print produced by the negative/positive method. Against this, the very nature of the reversal film emulsion makes it impossible to reproduce accurately more than a restricted range in subject brightness levels. It is because of this restriction that the user of reversal film is warned of the difficulties of photographing subjects of long brightness range. Best results are obtained with diffused or fairly flat lighting.

Reversal material is returned after processing as a single film ready for projection; the negative/positive technique, on the other hand, produces two films, one a negative and the other a positive print. Only the latter is suitable for projection, however, and unless further prints are likely to be required, the negative inevitably becomes an encumbrance, and mayjust as well be discarded - except by the advanced or specialised worker for whom the negative has a particular value in editing or cutting his material. The usual practice here is to edit a print taken from the uncut negative and then to cut the negative to match the edited print. A second print is then made from the cut negative to show the film in its final edited form.
REVERSAL PROCESSING

In processing by reversal, the aim is to produce a positive image directly. There are various ways of doing this, but with amateur movie films it is usual to employ a special type of emulsion, and to treat this with suitable chemical solutions to bring about the desired result. Briefly, the steps involved are as follows.

After exposure in the camera, the film is first developed to a negative in the normal way. It is then washed, but instead of being fixed, it is treated with a form of bleaching solution which dissolves the silver grains making up the grey negative image formed by the developer. It is important to note that the bleaching solution does no more than this, and leaves untouched the undeveloped - and still light-sensitive - silver salts in the emulsion which, in the normal way, would be removed by treatment in a hypo fixing bath.
Where once the negative image existed in the emulsion, the action of the bleaching solution leaves only gaps - more or less transparent according to the actual density of the negative image from point to point. The rest of the sensitive emulsion is still unaltered.

The next step is to re-expose the film so that the whole of the remaining sensitive emulsion is affected. This is done, not in a camera as in the first exposure, but in the open, to a naked lamp or white light for a sufficiently long period. The film is then put through the developer once again and a second silver image produced. A final treatment with hypo is sometimes given, but is scarcely necessary since no undeveloped silver salts remain to be dissolved away from the film.

Reference to Fig. 1 will help to explain how this process results in a direct positive image. Let us imagine that we are to photograph in our cine camera an object containing the three tones as shown at stage A. We will assume that conditions of exposure and development of the film are such as to give a negative image on the film as shown at stage B. For the sake of simplicity, this negative image shows complete blackening of the emulsion in the upper portions which received the greatest exposure, an intermediate degree of blackening in the lower portion where the exposure was less, and no blackening at all in the central region where little or no light was reflected from the original. Since we are not going to fix this negative in hypo, unexposed sensitive silver salts will be left in the film, in amounts reciprocally proportional to the extent of the exposure received by the film. Thus, the amount of this unexposed sensitive silver salt will be greatest in the central region of the image, somewhat less so in the lower portion and completely lacking in the upper portion.
NEGATIVE POSITIVE PROCESSING

In principle, the movie maker's negative/positive process is similar to that known to every still photographic worker. As its name implies, development of the camera film is stopped at the negative stage; the positive is produced by contact printing from this negative on to specially made high contrast (and usually fine grain) film, and developed in z positive-type developer.

On the face of it, the negative/positive process would seem simpler than the apparently complicated reversal processing procedure. Insofar as the actual processing of both negative and positive films is concerned, this is probably true. The difficult stage is the printing operation and it is unlikely that the amateur worker will be able to surmount this obstacle satisfactorily. Two problems have to be solved in making prints from movie negatives. The first one is mechanical and revolves around the provision of means for drawing both negative and positive films in intimate contact past a suitable printing aperture and exposing light. Apart from this there must be some means of spooling up both negative and positive film when exposure has been completed.

Negative Scene Changes and Printing Exposure Control

The second problem is optical, and is even more tricky to solve. Generally speaking, the average movie negative is up to 30 or 50 ft. long, depending on the film gauge employed, and within this negative there may be up to 10 or even more separate scenes. It is unlikely that the average negative density for all, these scenes will be the same, and some means must, therefore, be provided for varying the printing lamp exposure accordingly if a uniform print is to be obtained. Since the rate of travel of negative and positive films through the printing gate is set by the driving mechanism, the exposure can only be altered by varying the lamp intensity appropriately from scene to scene. Thus, not only must each scene change be located accurately on the moving negative as it comes within the printing gate, but, at that instant, the lamp intensity must be adjusted to the correct level. What this correct level is can only be determined beforehand by trial and error methods, using small lengths of film exposed and developed under known conditions.

Commercial film processing laboratories get round these problems by using special machinery in which scene changes on the negative are located automatically and the printing light intensity varied appropriately. Skilled operators are able to assess the exposure required for each scene with remarkable accuracy, and where necessary, to provide by means of short exposure strips, a range of picture densities from which the best effect can be selected.

Defects on Prints

Quite apart from the mechanical and optical problems mentioned above, there are other factors which intervene to make things even more complicated for the amateur film processor. No movie maker needs to be told how irritating are the showers of white spots which occasionally appear on his screen, sometimes heavy enough to resemble a veritable snowstorm. These spots can be traced to minute particles of dust on the negative, and during printing, prevent the light from reaching the positive film, so causing small clear patches on its surface. Nothing can be done to cure the trouble once it has occurred. The remedy is obvious. It is for this reason that commercial processing laboratories take such pains to see that the negatives they print are as clean as it is reasonably possible to get them.

A scratch is another irritating defect to be found on a print. Sometimes it is straight, sometimes it wavers and wobbles across the screen. It may be on the emulsion, or it may be on the celluloid side of the print. If on the print, and not too deep, it appears usually as a dark line on the screen; while if on the negative, it appears on the print as a white line. Usually, little or nothing can be done to remove a scratch when once it is formed, and here again prevention is the obvious aim.
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
TITLES AND SPECIAL EFFECTS

One of the operations which can safely be undertaken by the amateur movie maker, is processing the titles for his films. In general, there is no need to use reversal film, and some of the most easily read titles are, in fact, those made directly on positive film.

The title cards are best prepared by drawing or writing in black (Indian) ink on white card, or, if less contrasty results are required, on grey or lightly tinted card instead. The correct exposure to be given should first be determined by making a few trial shots with only short lengths of positive film in the camera, and then developing in a dish or jar. There is no need to take processing the films beyond the stage of producing a negative, since this will give you excellent titles in white letters on a black, or dark, background.

Development of the full titles is preferably carried out on the drum processing equipment already described, using a positive-type developer in the tank. Details of such a developer, ' which can be made up quite simply when required (it does not keep particularly well), are given with the formulae.

If preferred, titles can be made on negative film just as easily as on positive film, but they lack the brilliance and contrast of those made on the latter. The choice between the two is largely governed by personal preference.

Chemical Fades

A fade-in or fade-out can be made quite easily on movie film by means of chemical treatment. All that is needed is a fairly deep container, such as a jam jar or measuring cylinder and a seconds timer.

If positive film is to be treated then the image must become progressively darker until it is perfectly opaque.

To achieve a positive fade, therefore, we have to use the sort of chemical solution that will blacken the image completely, both silver and clear gelatine alike. A black dye (e.g. the proprietary compound `Fadene') is the most suitable for this. If, on the other hand, it is a negative, then the reverse is required and the image must become progressively lighter until only clear gelatine is left. For a negative fade we can try any of the normal reducers of silver solvents and the one-solution Farmer's reducer, is perhaps the most straightforward to use. This can most conveniently be made up by mixing equal proportions of 10 per cent. solutions of hypo and potassium ferricyanide. If the action is too vigorous, the proportion of the latter may be decreased or a weaker solution employed.

For both positive and negative fades, the method of treatment is the same. First fill up the jar or cylinder with the appropriate solution. Take a spare piece of the film to be treated (if none can be spared, choose a piece that closely matches it) and use the timer to show how long it takes, either to blacken, or bleach, the image completely.

The next step is to divide this time by the number of frames in which you wish the fade to occur - 12 is usual for a very short fade and 24 or 48 for a more leisurely one. This will serve as a guide for fixing the rate at which to withdraw the film from the solution.

Example:

Time taken to bleach (blacken) completely 3 minutes. Number of frames required in fade, 24

Thus, each frame has to be withdrawn 7.5 seconds after its predecessor.

The film to be treated is held vertically over the solution in the jar, and a small weight attached to its free end to prevent it from curling up over itself. It is then immersed in the solution up to the point at which the fade is to begin, and the timer set in motion. Taking the example quoted above, the film is withdrawn by one frame after 7 seconds have elapsed, by a further frame after 15 seconds and so on until the whole of the film is withdrawn. It is then thoroughly washed if a negative has been bleached, and hung up to dry.

Colouring Films

Movie films may be coloured in one of three ways:

1. Tinting, by means of staining compounds.
2. Toning, by means of chemicals.
3. Dye toning, by means of mordants and dyes.

The first method results in an overall colouration of the whole film, highlights as well as image, and while for certain effects this may be acceptable, it is obviously limited in its application. The procedure is perfectly straightforward and may be safely carried out on the sort of processing equipment already prescribed.

Toning, either by means of chemicals or by mordants and dyes, gives a more natural result as only the image itself is coloured, the highlights being left clear. The actual process to be used depends on the colour desired and any of the standard techniques may be employed. In general, the film to be toned should first be thoroughly washed in water and, as with tinting, the process is best carried out on the drum or frame processing equipment.

In deciding whether or not to tone a particular film, it is as well to remember that any trace of fog or veil in the highlights will tend to be intensified, and as such, will be more prominent in the finished result. In such a case, it might be advisable to remove the fog beforehand by careful reduction of the film.

Avoir 
                                    
2 ozs
176 grains
1 oz. 180 grains
141 grains
53 grains
88 grains
40 ozs
Metric

70 grams
10 grams
34 grams
8.8 grams
3.4 grams
5 grams
1 litre
1. First Developer

Sodium sulphite (anhydrous)
Hydroquinone
Sodium carbonate (anhydrous)
Potassium bromide
Potassium thiocyanate
Caustic soda
Water to make


The chemicals are to be dissolved in the order shown in one-half of the water at 125°F. Add the caustic soda last and make up to the full amount with cold water just before using.

Development time varies from 3 to 15 minutes at 65°F depending on the exposure received by the tilm. The best way to ascertain the correct development time is by processing short lengths of the film for varying times and selecting the most appropriate one by inspection of the results.
PROCESSING FORMULAE

The following chemical formulae are given to help those who wish to make up their own solutions. The warning should be made, however, that manufacturers' recommendations vary from time to time and it is a wise precaution to ascertain for any particular type of film, the current processing instructions issued.
Reversal Processing - suitable for Pathe S.S. Pan
2. Bleach

Potassium bichromate
Sulphuric acid (conc.)
Water to make


176 grains
193 minims
40 ozs


10 grams
10 cc.
1 litre
Add the acid slowly to the solution of bichromate. Considerable heat may be developed locally, and it is advisable to stir the solution while the addition is being made.
3. Clear

Sodium sulphite (anhydrous)
Water to make


2 ozs
40 ozs


50 grams
1 litre
4. Second Developer

Sodium sulphite (anhydrous)
Metol
Hydroquinone
Sodium carbonate (anhydrous)
Potassium bromide
Caustic soda
Water to make

Develop until film blackened throughout (4 to 5 minutes).




1 oz. 100 grains
35 grains
88 grains
1 oz. 100 grains
35 grains
40 grains
8 ozs


35 grams
2.5 grams
5 grams
35 grams
2.5 grams
2.8 grams
200 cc
5. Fix

Hypo
Sodium bisulphite
Chrome alum
Water to make


1.5 ozs
35 grains
35 grains
40 ozs


38 grams
2.5 grams
2.5 grams
1 litre
Negative Developer

Metol
Sodium sulphite (anhydrous)
Hydroquinone
Borax
Water to make

Development will take from 7 to 15 minutes at 65°F, depending on the type of film and the degree of agitation received during processing.

To mako up the developer, use water at a temperature of about 125°F. Dissolve the metol in a small quantity (e.g. 8 ozs.) first, and then put in the Hydroquinone. Add to the sulphite and borax, already dissolved in the rest of the water.


36 grains
4 ozs
88 grains
36 grains
40 ozs


2 grams
100 grams
5 grams
2 grams
1 litre
Positive Developer

Metol
Sodium sulphite (anhydrous)
Hydroquinone
Sodium carbonate (anhydrous)
Potassium bromide
Water to make

Dissolve in the order shown, using water at about 125°F. Development will be complete in 3 to 5 minutes at 65°F depending on the degree of agitation received by the film during processing.


9 grains
2 ozs
88 grains
1 oz
27 grains
40 ozs


0.5 grams
50 grams
5 grams
25 grams
1.5 grams
1 litre
Intensification.

Bleaching Solution

Potassium bichromate
Hydrochloric acid
Water to make


The film to be intensified should first be thoroughly washed before treatment in the bleaching solution. Treatment is complete (usually in about five minutes) when all of the black silver image has become yellowish-orange in colour.


35 grains
40 minims
40 ozs


2 grams
2 cc.
1 litre
Reduction

1. Reducing Solution

Potassium ferricyanide
Water to make

As with intensifying, the film to be reduced must first be thoroughly washed before treatment in the reducing solution.

The length of treatment will vary from about one to five minutes, depending on the extent of reduction required, and it is advisable to make a test beforehand on a short piece of the film to be treated. Then transfer to:


130 grains
40 ozs


7.5 grams
1 litre
2. Fixing Solution

Hypo
Water to make

Treatment in the fixing solution is complete within five minutes, after which the film should be thoroughly washed ! and dried.

The whole operation can be safely carried out in white light and if, at the end, the image is still too dark, it may be repeated from the start.


10 ozs
40 ozs


250 grams
1 litre
3. Toning

Bleaching solution
Potassium ferricyanide
Water to make


1 oz. 260 grains
80 ozs


20 grams
1 litre
(a) Sepia

Sodium sulphide
Sodium sulphite (anhydrous)
Water to make

(b) Reddish-Brown

Copper chloride
Water to make

(c) Grass Green

Iron perchloride
Potassium bromide
Oxalic acid
Water to make


Wash film thoroughly after toning. The iron-toned image is liable to attack by alkalis in ordinary tap water and should, therefore, be rinsed in changes of water made slightly acid by the addition of about 10 ccs. per litre of 10% hydrochloric acid or acetic acid.





350 grains
175 grains
80 ozs.



4 ozs
80 ozs



1 oz. 260 grains
350 grains
350 grains
80 ozs




10 grams
5 grams
1 litre



50 grams
1 litre



20 grams
10 grams
10 grams
1 litre