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PROCESSING REVERSIBLE CINE-FILM
M JACQUES HENRI-ROBERT, president of the Amateur Cinematographic section of the French Photographic So* ciety, has recommended the following procedure for reversal of amateur cine film.
The first developer is a paraphenylenc diamine developer made us as follows:
Paraphenylenc diamine 1 0 gms. 90 grs.
Soda sulphite, anhyd. 45 gms. 400 grs.
Caustic soda 1 10 gms. 90 grs.
Potass, bromide 4 gms. 3 5 grs.
Phenosafraninc, 1 : 1,000 sol. 50 c.c.s. 1 oz.
Water 1,000 c.c.s. 20 ozs.
The paraphenylenc diamine, finely powdered, is first dissolved in very hot water and the sulphite then added. The other constituents are dissolved in the cooled solution. Before use, the developer is filtered through glass wool.
At 65° F. a well-exposed film needs 15 mins. development, and this time should not be varied by more than 5 mins. The developer may be used for several films in succession. The developed film is well washed — for at least five minutes in running water — before reversal.
The reversal bath is made up from the following stock solution:
Potass, permanganate ____. 2 gms. 18 grs.
Water 1.000 c.c.s. 20 ozs.
To make the working bath, add to the above bath 80 c.c.s. (l]/z ozs.) of dilute sulphuric acid, made by adding 10 parts of the concentrated acid to 100 parts of water.
When the film has been immersed in this working bath for about a minute, white light may be switched on. The film must remain until all the black silver deposit has disappeared, the normal time of immersion being 7 to 8 minutes. It is then washed for five minutes in running water. This bleaching bath should not be used again.
For clearing, the film is placed for' five minutes in the following bath, to be used once only:
Sodium metabisulphite. anhyd. 200 gms. 4 ozs.
Water 1,000 c.c.s. 20 ozs.
The cleared film is then re-developed in a freshly made developer consisting of:
Sodium bisulphite lye 50 c.c.s. 1 oz.
Sodium hydrosulphite 1 0 gms. 90 grs.
Water 1,000 c.c.s. 20 ozs.
The hydrosulphite used in this developer, it should be noted, is an entirely different compound from the hyposulphite commonly used.
Re-development takes from 10 to 20 minutes and must be done under the strongest illumination available, e.g., full daylight. This solution should be used only once.
The re-developed film is washed for fifteen minutes in running water before drying, in the usual way.
A positive film which is too dense may be reduced by treatment in a very weak solution of acid permanganate, viz. :
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