Nitrate base, the pioneer of motion picture film bases, retired from our cameras and laboratories about 1951-52. Still, its very long shadow of distinguished commercial motion pictures and film records haunts many film vaults. Nitrate base films must be handled with informed care. Cellulose nitrate base film is relatively unstable. If you store it in large quantities of about 5,000 feet or more and in non approved storage cabinets without proper ventilation, it becomes a fire hazard. Admittedly, it takes a bit of pushing to cause it to burst into flames spontaneously. For example, in one laboratory test, combustion occurred with a decomposing 1,000 foot roll of film only after it was kept at 41°C (106°F) for 17 days tightly encased in a can wrapped in insulation to retain the heat of decomposition. However, even a minor fire can cause major film losses. This example may not be that different from some storage lofts in the summertime that are uninsulated. Cellulose nitrate decomposition is the villain. It shrinks, even to the point of becoming unusable. Furthermore, as the film breaks down, it gives off nitric oxide, nitrogen dioxide, and other gases that yellow the film base, yellow and soften gelatin, and oxidize the silver image. Later, the base cockles, becoming very brittle and then sticky. Finally, it disintegrates completely. This inevitable deterioration is usually gradual, but elevated temperatures and humidity speed it greatly. While it deteriorates, nitrate base film makes a kind of pressure cooker of the film can in which it rests, especially when it's taped closed. If the gases can't escape, heat builds and spontaneous combustion may not be far behind. Therefore, nitrate film must never be closed in. Escaping toxic gases (powerful oxidizing agents) can attack nearby acetate and polyester base films, so store nitrate films in their own special place and not in a place too heavily concentrated. If the conditions are right, their image layers may last for decades or generations. Because of their great value, many nitrate base films have been reprinted on current longer lasting safety base. Somewhere, nitrate film is still with us, so we offer a few more comments. Probability of Rapid Decomposition If you store old nitrate base films, the first thing you need to check is the temperature of the storage area. High readings of the temperature and/or the relative humidity are unfavorable to nitrate and to other films. Are the by products of decomposition being discharged from the storage area? Is there too much nitrate in a confined area? The more rolls collected in one place, the greater the chance of trouble. with nitrate film, it's important to design separate and specialized storage compartments. Inspection and Segregation of Nitrate Base Film Identification is the key to initiating the proper handling of nitrate film. You need to properly identify the films in your vaults and storage areas. Don't assume all films to be acetate or polyester when some may be nitrate. Some rolls may be spliced mixtures of each. Kodak never produced 16 mm or narrower film on nitrate base. Some may have been slit to 16 mm from 35 mm for whatever reason. Also, Kodak never produced 70 mm or 35 mm color camera original or color print films on nitrate base, but they did produce on nitrate base a special black and white Eastman nitrate film for use in making 35 mm and 70 mm imbibition films (dyed by the Technicolor process). It's important to know exactly what types of film are in your possession because nitrate fumes and fire are a threat. Conditions that may only marginally harm the acetate films can cause a nitrate base to become very dangerous. Unless you can detect some deterioration, you may have a hard time differentiating nitrate from acetate base films. Edge identification may establish the difference the easy way. You can use ultraviolet lamps to identify EASTMAN Triacetate Films by the resulting fluorescence. A different identification tool is your nose. Cellulose nitrate has a characteristic acid odor, similar to that of nitric acid. This odor is unmistakable when a quantity of nitrate film has been stored, especially in a nonventilated area. Evaluating the Extent of Deterioration The nitrate film you have in storage may be middleaged, but if it was properly stored, it may be quite usable. However, if it was neglected, it may be showing signs of early deterioration. One way to determine the extent of deterioration is to look at the color of the base. If it's yellowish, or even amber, sulfiding has begun because of silver in the emulsion and some yellowing of the gelatin. The confirming test is to see if the film base is brittle and breaks easily on being bent in half, especially with the emulsion side out. At this stage, the gelatin is probably soft enough to dissolve readily if the film is wetted. If these symptoms of decomposition are found, handle the film with care and keep it dry. Duplicate it soon after inspection, drying, and cleaning, because buckled film and sticky gelatin may make duplication later more difficult or perhaps impossible. Spontaneous Combustion Spontaneous combustion is self ignition of combustible material through chemical action (as oxidation) of its constituents. It develops from knowable conditions, such as deterioration, and with proper observation and care, you can prevent a chemical reaction. Nonpreventive measures, whether it's in hay, oily rags, or nitrate film, can result in a fire. With the information given in this section, you can prevent the threat of spontaneous combustion. Apparently, fire isn't caused by cellulose nitrate in good condition. But in the advanced stages of decomposition, self ignition takes place at sustained temperatures only slightly above 38°C (100°F). If undetected, heat producing deterioration and high temperatures, with consequent heat buildup, coincide. Such combustion isn't nearly so spontaneous as its name seems to imply! Storage Vaults and Conditions Carefully examine all the materials known to be on nitrate base. Detecting unstable nitrate film is by far the most important way to preserve this material. If decomposition isn't found quickly, complete destruction of the film record may result. Spot inspection only needs to be done once a year if you follow the recommended storage conditions, and once every 3 months if adverse conditions exist. Any nitrate film that is badly buckled or sticky is in an advanced stage of decomposition. You may be able to duplicate some of these badly buckled or deteriorated films, or they may yield a fair quality print. Urgency is the word. If the film base is heavily stained and moisture from our breath makes the gelatin slightly sticky, the negatives or prints must be duplicated within 2 years while maintaining proper storage conditions. Never wet a decomposing nitrate base negative; the gelatin may be readily dissolved. If you must remove surface dirt, use a quality cleaner carefully. Many old negatives have an iridescent dichroic or silver sulfide stain, usually on the surface of the gelatin. This is a further sign of old and deteriorated film. Store these negatives only in small quantities and in different locations. The production of chemical vapors and heat from large concentrations of nitrate films demands special storage conditions with a special exhaust and ventilation system. This storage area should never be near safety films. Never store any nitrate base materials in sealed containers or without ventilation. Such dead storage simply increases the rate of decomposition. Pack the reels loosely in ventilated metal boxes or cabinets, and store them in a room apart from all other photographic materials. Do not let the storage area temperature exceed 21°C (70°F). If you achieve a lower temperature without increasing relative humidity above 45 percent, that s even better. Relative humidity below 40 percent retards decomposition even more, but makes the film more brittle. Help for Owners of Nitrate Base Film Nitrate base films have been out of common use so long (since about 1951-52) that expertise in handling them is not commonly offered, but there are facilities that do offer this service. Unless you are an expert concerning the characteristics of nitrate films in various stages of decomposition, don't unroll the films. Let the experts do it. For help determining the historical (not monetary) value of any material on nitrate base, contact a local historical film association or International Film Archive, FIAF Secretariat, rue Franz Merjay 190, 1180 Brussels, Belgium. If they can't help you, they'll direct you to someone who can. If the film has value or you decide to have it duplicated, even if it isn't unique, one of the film archives can give you advice on the procedures for arranging duplication. Dave Edgar Cinematographer/Steadicam operator [log in to unmask] ========================================================= Important Subscriber Information: The Museum-L FAQ file is located at http://www.finalchapter.com/museum-l-faq/ . You may obtain detailed information about the listserv commands by sending a one line e-mail message to [log in to unmask] . The body of the message should read "help" (without the quotes). If you decide to leave Museum-L, please send a one line e-mail message to [log in to unmask] . 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