International photographer (Jan-Dec 1934)

tories constitute, in truth, a research university in the sphere of photographic science. There, on our right, is a huilding in which silver, by modern alchemy, is turning into materials far more precious to this civilized era — motion picture him to entertain every week nearly as many persons as the population of the United States, spools of Kodak Film and CineKodak Film for pleasure and sentimental record, sensitive substances for the camera craftsmen who satisfy many civilized needs and tor scientists who use photography in ferreting out the earth's remaining secrets, recording surfaces to capture the pictures that illustrate newspapers and magazines the world over — film and sensitive paper for every conceivable purpose. Let's begin our inspection by seeing what happens to the silver. The treatment of this raw material will give us something of an introduction to Kodak Park's manufacturing methods. Comparatively little bullion is stored in Kodak Park at one time. Every day, under heavy guard, a shipment arrives to maintain the supply. A single safe, holding about three tons of bars, which is less than a week's supply of raw material, is the respository from which the silver flows. Into every bar a hole is drilled, a record number is punched. Chips from the drillings are promptly tested by the department handling the silver and, in addition, by the Industrial Laboratory, which is charged with the responsibility for the quality of all raw materials. Impurities are rarely found in Kodak Park's silver; yet inspection continues year after year. If a trace of copper or iron were permitted, unchecked, to go into the manufacturing stream, endangering photographic effectiveness, later tests would discover and eliminate the result, but time and other materials would have been wasted in the meanwhile. Production schedules would have been interrupted. Therefore, Kodak Park tests every ingredient as In coating film base, dim colored lights or total darkness is required. well as finished products and products in process of manufacture. Of the thousands of employees at the plant, hundreds devote their whole time to the careful inspection of materials at every stage of evolution into finished photographic products. Observing the first step in converting bar silver into photo-sensitive materials, we shall instinctively feel that The Research Laboratories occupy this spacious building near the Park entrance. we are witnessing wanton destruction. With our realization of the worth of silver in its original form, we can not avoid a shock at seeing the bars of metal dissolved in nitric acid until all is fluid and nothing solid remains. The nitric acid, it is worthy of note, is made at Kodak Park under scientifically controlled conditions leading to purity of grade. The silver nitrate solution we have seen compounded is siphoned from its porcelain bowls into troughs, whence it runs through glass tubing to an evaporating room on the floor below. There, men wearing rubber aprons and rubber gloves guide the flow into other bowls, which are set on heated tables. The heat drives off water from the solution ; and, when the concentrated solution cools, the silver nitrate crystallizes. Silver nitrate in this form would be more than pure enough for most uses — but photographic manufacture is an exacting master. Consequently, the crystals are once again dissolved in distilled water and once more crystallized. This operation is repeated many times — until all impurities are removed. Final evaporation leaves crystals appearing like soap flakes but more vitreous and brittle. Then come careful drying processes. Silver nitrate is sensitive to light — a fact ascertained by Arab alchemists seven centuries before Columbus discovered America — gradually losing its whiteness under the influence of the sun's rays. It is this basic chemical fact that makes photography possible. The discovery of the transparent, flexible base of photographic film constitutes the Eastman organization's greatest contribution to photography and motion pictures, and in this connection a humbler material now enters the process of film-making. The film support, or base, is composed of cotton that has been treated with a mixture of nitric and sulphuric acids to render it soluble in a mixture of solvents, the chief of which is methanol (wood alcohol). The "dope" thus obtained, having the consistency of honey, is spread on the polished surfaces of great wheels that run continuously, night and day, month after month. Heat around the giant wheels drjves the solvents from the "dope" and permits the nitrated cotton, or cellulose nitrate, to assume the form of a thin, transparent layer on the surface of the wheels. After various convolutions within a machine, a wide strip of finished film base emerges and is wound up in a roll like newsprint paper. Please mention The International Photographer when corresponding with advertisers.