Film Preservation 101: Is Nitrate Film Really Dangerous?

Is Nitrate Film Really Dangerous?

Nitrate film is a material we don’t often encounter at the National Archives for obvious reasons. After the devastating 1978 nitrate vault fire, the agency quickly copied any remaining nitrate to acetate or polyester safety film and disposed of the original reels.

When we do come across a reel in a new accession or a preservation request from one of the presidential libraries, I can tell you we’re not overly concerned that the film will burst into flames as we wind through it. Because here’s the deal: when handled and stored properly, nitrate film won’t just explode in your hands or spontaneously combust.

Various stages of nitrate deterioration, from the salvageable to the lost cause.

The short answer to “Is nitrate really dangerous,” is yes and no, because it depends on the situation and is a little complicated. When it catches fire, nitrate film will burn fast and hot, is virtually inextinguishable, and if stored in vaults without adequate venting to release pressure, can end with one or more explosions. In addition, the fumes produced when it burns are noxious and can sicken anyone in the vicinity. There are stages of deterioration that lower the flash point and make it more likely that a very hot day could cause a fire. It has the potential to be really scary, but it’s not the whole story.

There’s a quote from Orson Welles that’s rather famous among film archivists. Welles was asked about the fire that burned the negative of Citizen Kane and responded: “Film has a personality, and that personality is self-destructive. The job of the archivist is to anticipate what the film may do—and prevent it.”[1] The sentiment is true regarding both the flammable nitrate stock and the non-flammable acetate stock, because as it turned out, “safety” film is just as self-destructive and develops vinegar syndrome if not stored in the correct conditions.

The task of caring for nitrate film is daunting, but we know a lot about how to properly handle and store nitrate, and fires don’t just happen. In fact, the National Archives was one of the major players in determining how to avoid disastrous nitrate fires, which makes it that much more heartbreaking that we ended up losing millions of feet of film to a vault fire.

RED # 1835764-NA-162
Photograph of Sound Engineer Glenn C. Henry of the Division of Motion Pictures and Sound Recordings, holding a reel of motion picture film in the film storage area, 10/12/1937. 64-NA-162 (NAID 5928166)

Creating a National Hall of Film Records

Parallel worries about the preservation of historical moving pictures and preventing fires pre-dated the founding of the National Archives. According to a Feburary 1924 article in New York’s Morning Telegraph, Will Hays, the chairman of the Motion Picture Producers and Distributors of America, had been working with President Harding on a plan to convert the White House cellars into temporary film vaults until a permanent structure could be built.[2] After Harding’s death, Hays continued work with President Coolidge to establish a federal building to preserve historically important film. During Coolidge’s administration, Congress passed the Public Buildings Act, which appropriated funds for a national archives building. The National Archives Act, passed by Congress in 1934, created the agency and included a provision for collecting and preserving motion picture films and sound recordings. In a 1935 letter to Robert D.W. Connor, the first Archivist of the United States, President Roosevelt wrote that he was “unequivocally in favor of preservation of these definitely historic records,” although he was concerned enough about the risk of storing nitrate film that he suggested building the vaults underneath Constitution Avenue in order to separate them from the paper records.[3]

Setting Standards for Nitrate Storage

The National Archives partnered with the National Bureau of Standards to establish specifications for appropriate containers and vault construction for nitrate. The National Archives Motion Picture Division designed a ridged steel can with a loose-fitting lid to allow off-gassing and contain any fire that might start. A 1936 press release describes a test conducted at the Bureau of Standards with representatives from both the National Archives and the Society of Motion Picture Engineers:

“The design calls for special breather vents so that the film inside can give off its fumes freely. The container is also explosion proof. A thousand feet of old and badly deteriorated film was placed inside this container and the lid held in place by iron bands. The film was then set on fire and although a terrific pressure was set up, resulting in a great cloud of smoke and ultimately a flame that roared for several minutes, the container did not explode and the breather vents demonstrated complete ability to permit pressure to escape.”[4]

The director of the Motion Picture and Sound Recordings Division, John G. Bradley, spent several years designing and testing a cabinet to store nitrate that would prevent fire from spreading if it were to break out in a single can. A total of 66 tests were conducted, the final in which the investigators built a fire outside the cabinet that burned at 1500 degrees Fahrenheit. The film inside stayed at a temperature well below the flash point for nitrate and was unscathed.

In 1940, the U.S. Patent Office awarded Bradley a patent for his design. The cabinet was described in an issue of the National Archives newsletter, Archiviews:

Bradley Granted Patent. John G. Bradley, Chief of the Division of Motion Pictures and Sound Recordings, the National Archives, has just received Letters Patent No. 2,190,229 from the Commissioner of Patents covering what appears to be a unique storage cabinet for motion-picture films. The cabinet is so designed that a fire in any one compartment (a remote possibility, according to Mr. Bradley) or from any other source will operate a water sprinkler located in the top of the flue at hte rear of the cabinet. In such case the sprinkler automatically throws a spray of water simultaneously into each compartment of hte cabinet, thus affoding instant protection to all the films stored both from a spread of fire and from excessive heat. The water thus sprayed into the compartment falls on showerproff containers holding the films, and completely encases hte containers in a thin sheet of water. In a few seconds, according to the claims, the water fills up in the bottom of each compartment and forms a "water seal" at the juncture of two overlapping baffles in the rear so that the heat from the flue or from adjacent compartments is effectively kept out of unaffected compartments. One of the principal features in this patent is the provision that keeps the water constantly moving or cascading from each compartment to the one next below it, thus the water never gets overheated and effectively carries off the heat units resulting from combustion. Mr. Bradley points out that the cabinet, although primarily designed for the storage of motion-picture films, is adaptable to the storage of any type of inflammable material--still films, documents, papers, etc. Prior to the filing of claims of this design, a total of 66 burning tests were made in which both internal fires (fires inside the cabinet) and external fires were deliberately started as a means of measuring the effectiveness of the cabinet. In the last test the cabinet was placed inside of a specially designed cubicle where approximately 1400 pounds of combustible material was piled around the cabinet and ignited. This represents a rather high concentration of combustibles and approximates the condition one would find in a burning building. The combustibles were ignited and the fire burned actively for 3 1/2 hours, after which it was allowed to diminish. The test was terminated at the end of 24 hours. The maximum temperature reached on the outside of the cabinet was approximately 1500 F; the maximum temperature reached on the inside of the cabinet, however, was only 148 degrees--a temperature considerably below the flash point of film. None of the film was damaged.

The National Bureau of Standards halted testing in 1941 when the United States entered World War II and all resources were redirected toward the war effort. In 1948, experiments to establish “recommendations for safe storage” resumed with the Inter-agency Advisory Committee for Nitrate Film Vault Tests. A large vault was constructed and a range of variables tested, including how much film was stored in the vault, types of sprinklers and water flow rates, various film containers and racks, and the presence of thermal insulating material.

The results, published in a 1956 report, found a combination of compartmented storage racks and sprinklers did the best job at preventing the spread of fire to adjacent film cans. With the sprinklers, anywhere from 2.2% to 92.9% of the film in a vault was destroyed. Without sprinklers, no films survived, except when they were stored in closed-front, compartmented racks like those designed by Bradley. Further, the report concluded that to avoid explosions, a nitrate film vault should include a vertical vent that opened when pressure reached a critical point. The investigators also recommended that “any device such as electric or heating equipment that might ignite film should be placed and enclosed in such a manner that contact with film is not possible.”

When fire broke out in Building A of the Suitland nitrate vaults, the National Archives was in violation of several of the principles that it helped establish over years of research. The sprinklers were turned off because workmen were upgrading them, and the workers were using power tools and perhaps even a blowtorch in the vicinity of highly combustible materials. With none of the designs in place that were intended to prevent the spread of fire, the conflagration moved quickly and the vaults exploded.

If Only…

Nitrate film is flammable and there is risk in keeping nitrate film. A nitrate fire is very dangerous, but nitrate film itself is not imminently dangerous if not given the conditions in which to burn. New nitrate film has not been produced for nearly 70 years and yet archivists are still uncovering nitrate film elements that have existed happily for 80, 90, 100 years or more. The George Eastman Museum projects original nitrate prints in a three day festival every year. We shouldn’t fear nitrate film, but we should respect it and always treat it correctly.

Many, many thanks go to archivist Alan Walker, who has been processing the National Archives’ institutional records and shared with me all of his discoveries related to the motion picture holdings.

[1] Quoted in This Film is Dangerous, pg. 27, originally published in Our Movie Heritage by Tom McGreevey and Joanne L. Yeck (Rutgers University Press, 1997), pg. 115.

[2] “Federal Hall of Film Records Looming” New York Telegraph, Sunday, February 24, 1924. News clipping in RG 64.

[3] “FDR Suggests Nitrate Film Vaults Under Constitution Ave, Oct. 1935.” RG 64, P 39, file 144-43, pt. 4

[4] “Test of Vented Film Container, 1936” RG 64, P 75

Sources and Further Reading:

This Film is Dangerous: A Celebration of Nitrate Film, edited by Roger Smither and Catherine A. Surowiec, contains dozens of essays about the history of nitrate film preservation. Of particular note are the “Calendar of Film Fires” (pg. 429) and Sam Kula’s essay “Mea Culpa: How I Abused the Nitrate in My Life,” pg. 163. In this essay, Kula makes the argument that nitrate fires were relatively uncommon given the amount of nitrate film in existence, and that some form of negligence can usually be found as the cause. The piece was also published in The Moving Image (Vol. 1, No. 1, pp 198-202)

Charles “Buckey” Grimm, “A History of Early Nitrate Testing and Storage, 1910-1945.” The Moving Image: The Journal of the Association of Moving Image Archivists, Vol. 1, No. 2, Fall 2002, pp 21-38.

“Film Vaults: Construction and Use.” John G. Bradley’s paper, presented to the Society of Motion Picture Engineers, October 25, 1948, published in the August 1949 issue of the SMPE journal.

“Fire Effects and Fire Control in Nitrocellulose Photographic-Film Storage.” By J.V. Ryan, J.W. Cummings, and A.C. Hutton. National Bureau of Standards Building Materials and Structures Report 145. Issued April 2, 1956. Available on the GPO website.

Anna Dobringer, “The Wooden Vault. A Unique Approach to Nitrate Film Storage at Filmarchiv Austria,” Journal of Film Preservation, pp 111-116. Research into better storage conditions for nitrate film has not stopped. The Filmarchiv Austria’s new nitrate film vaults were built to be more energy efficient and promote ventilation, which has proven to be a major factor in preventing nitrate film deterioration. Wood is a surprising choice as a building material, but their research has shown it is a better insulator than concrete and is more stable for longer when a fire breaks out.



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