Another Substitute for Cellulose Nitrate: Robert W Carter and Aluminium
All weren’t convinced of the stability of long term film on cellulose acetate, nor the permanence of the silver image. Persuaded of the instability of nitrate, and very circumspect about the stability of acetate, a photographer from Toronto, Robert W Carter did, in the 1920s, perfected a procedure of photography on metal. Kalograph, that was the object of commercial exploitation in England by the society Permanent Reproductions Ltd from 1929. Le Kalograph is a procedure of photography that precondition the establishment of a negative transparent, weave [treme] that if desired can reproduce an image of continuous tone. The plaque is an alloy of aluminium and copper. The procedure was never revealed. Apparently, probably the imprinting the photographic image is rendered permanent by the cooking in an oven of the pigment of which the composition is not given.
The description of the operations given by the British Journal of Photograhy of the 12th of April 1929 is extremely evasive. It alludes to a sensitising solution and after exposure in a finishing bath, followed by immersion in a colouring solution and rinsing under running water before cooking. Therefore the Kalograph gives an extremely stable image, resistant to heat and humidity that can exposed to the open air and resistant to intemperate variations. These plaques can be cleaned with water or even with a rag imbued with petrol. They can be bent or twisted without crackling the image. According to BJP “apart from deliberate or most careless ill usage the photographs are indestructible”. 261
In 1936 Carter presented to the Committee for Library Reproduction a communique on the product derived from Kalograph that, according to him, could resolve all the problems of conservation, as much for the cinema as for documentary applications, aluminium film. Carter underlines in his intervention the relative instability of cinematographic film.
261 BJP, April 12, 1929, p.211.
“When the residual solvent leaves this material it becomes brittle and disintegrated, even under excellent storage condition 262”: Carter wasn’t precise about what he understood by excellent storage conditions. We know also that the disintegration of nitrate is a complex phenomenon that even if Carter’s explication is not false does not result from the evaporation of solvents. The recent attitudes, lead in England by Norman Allen and Michael Edge at the Manchester Polytechnic have deepened the understanding of the degradation of the nitrate support which don’t differ fundamentally for the acetate support. The polymer nitrate or triacetate lose their acid groupings that were grafted on the cellulose, the acid serves as a catalyser to a reaction of hydrolysation that manifests itself, as a rupture in the bindings between the atoms and this in the presence of water. Therefore destruction by hydrolysation of support with crystallisation of the plasticisers and as a manifestation loosening of acetic acid in the case of acetate, nitric in the case of nitrate.. Acetate in decomposition manifests itself by an odour characteristic of vinegar where the name vinegar syndrome comes from. 263
Carter expresses extreme prudence with regards to recent conclusions of the Bureau of Standards.. The Bureau of Standards in their report on acetate film states that it seems to have the possibilities for permanent record but only time will tell. 264
The nitrate, according to Carter, absorbs humidity rapidly, loses its flexibility, and other mechanical properties under the effect of heat and light. It is correct that the nitrate absorbs a appreciable quantity of humidity (but much less than the gelatine kind so that the quantity of water absorbed by a film emulsion holds more to the gelatine than to its support), and that environmental factors that accelerate the degradation of the nitrate are primarily humidity and heat. Without being a chemist Carter sensed that the embrittlement of the support didn’t have for origin, like we could have thought an excessive dryness, but on the contrary excessive humidity because the hydrolactic process is directly linked to the presence of water in the material.
We know today that the symptoms are slightly different, nitrates and acetates degrade in much the same way and often at the same speed. Carter created the initiation of mechanisms that would not be analysed ‘til half a century later.
262 Journal of Documentary Reproduction, 1938, vol. 1, no4, p.357
263 Mechanisms of Deterioration in Cellulose Nitrate Base Archival Cinematograph Film. – European Polymer Journal, 1990, no.26, p. 623-630
264 JRD, art. Cit., p. 358
In the 1920s the causes of degradation of the nitrate support are not clearly analysed and the acetates are too recent for the degradations to have already manifested themselves. This is why a totally different support, like aluminium, gives rise to great expectations. From 1924 the more severe tests seemed to show the stability of Carter’s process. The Toronto Saturday Night from the 1st of November 1924 concludes to the superiority of Carter’s process. “Any document or portrait can, by the Carter process, be reproduced with minute faithfulness, on metal, and rendered permanent and fadeless for all time”.
From there was born the idea of applying the process on similar cinematographic film, According to Carter metal film presents nothing but advantages and particularly in micrographic applications. The film is permanent, offers a mechanical resistance very superior to that of nitrate and is totally incombustible. It can be stored without particular precautions, get rid of the need for insurance and security in projection rooms and does not change the responsibilities of projectionists because it doesn’t require any more training in use than its counterparts. There doesn’t exist, to our knowledge, any proof of commercial success for aluminium film. It would have been produced from 1938 by the Fischer Film Corporation. The Scientific American report:
“Of particular value for educational and archive purposes is an aluminum motion picture film developed by the Fischer Film Corporation. This film being opaque, must be projected by means of reflection, a principle which is well known and which gives good results both for picture projection and for the reproduction of soundtracks. Existing transparent negatives may be used for printing metal positives. Some of the advantages claimed for the new aluminum film are that it is not flammable and does not produce any gases, as is the case with certain standard Celluloid base films. Aluminum film is reported to be virtually indestructible, samples have been projected 1500 times without any perceptible wear. The metal film is permanent, there is no shrinkage and it never cracks or grows hard. It can be used in all climates from frigid to tropical, resisting dampness, mold, heat and cold.
Because the film base is opaque, both sides may be used, thus cutting in half the number of feet of film required for a certain projection time. The cost is reported to be extremely low, not only because of the cheapness of the film base, but also because of the fact that only 50% as much footage is required” 266.
Carter’s process was never employed long term in cinema. It is not even certain that it went past the stage of experimentation. The screen did not receive incidental light, going through a transparent support, but a light very partially reflected by an opaque support. The loss was considerable (perhaps 80%), we conceive that the projection on large screen was rendered practically impossible by the extraordinary light intensity that it required, and the process could only be used on small sized screens.
The story of film on aluminium is full of shadows. The written testimonials are few. The experts of the IPI [Image Permanence Institute] whom we interviewed had no relevant information and the time has come where microfilm specialists from Robert Carter’s era can no longer be interviewed. The memory of the few rare survivors who were pointed out to us are no longer capable of testifying.
We find forty years later, the announcement of a process a little different but calling on the same support, the aluminium film. In 1986 the Digifilm society announced a photographic film of extreme stability, very great mechanical resistance, resolution and a superior contrast that would have permitted the recording on the same support photographic images and numerical information. Aiming at micrographic applications (Digifilm had put an announcement in the IMC journal) the film could have resolved the problem of recording on the same support, of a micro image and terms of indexation, or even better a cinematographic image and numeric soundtrack of high quality. According to the president of the society, John Nelson, the completely new film composition utilises a solid metal imaging layer. 266
In 1989 John Nelson previewed the product 267. Nobody today knows what became of it. In 1995, Nelson doesn’t appear on the files of adherence to the AIIM. The staff of Digifilm would have without doubt known the fate of Carter’s process when in 1930 Carter’s process was in competition with an unstable acetate support and at the same time the unstable and dangerous nitrate. Whereas Digifilm throws itself to polyester, which is stable, uninflammable and high mechanical resistance. In 1936 even if the stability of films reserved a few surprises conservation of photographic supports was the subject of scientific study and research to increase its longevity. On the eve of the Second World War cinematographic film became a veritable archival support.
265 Scientific American, vol. 159, 1938, no.1, Jul., p. 36
266 IMC Journal, 1986, vol. 25, Sept/Oct., p. 28.
267 We have personally told in an honest manner, M. John Nelson in the offices of AIIN at Silver Spring in September 1989. The communiqué that was written on this process was succinct and takes nothing away from the nature of the process. The consultation of Fisher from AIIN in September 1995 has not enabled us to find trace of him.