Nitrate photographic negatives were among the first on a light-weight “stable” flexible base. Before them were the heavy and fragile glass plates. Needless to say, the new base greatly enhanced the photographer’s abilities by significantly reducing weight and volume as well as shipping and carriage requirements.

If you grew up with film before digital you may recall seeing the edges of film marked as “Safety Film.” This is because those films were no longer on nitrate bases, but were first on cellulose acetate (“acetate” film) and later, polyester.

The first flexible film base, cellulose nitrate (hence “nitrate” negatives) was commercially produced in 1888 by George Eastman in his Kodak camera. This unleashed a whole new world of photography for amateurs and professionals alike. It brought the camera into the home.

While this was a great technological leap forward for photography, it had some dangerous baggage. Another name for cellulose nitrate (or nitrocellulose) is gun cotton for a very good reason—it was a very powerful explosive. It first saw use as gun powder for artillery where its power of gas generation was six times that of black powder. It was later used in explosive warheads of shells and torpedoes and for blasting in mining and construction.

It saw other uses as well, some not as successful. As the supplies of ivory began drying up in 1869, the billiards industry offered a prize to whomever came up with the best replacement for ivory billiard balls. John Wesley Hyatt won with a new material he invented called camphored nitrocellulose. It was briefly popular, but the balls were extremely flammable, and sometimes exploded upon impact, which added an interesting dimension to a game of pool.

In use with film, however, it was extremely dangerous, especially when used in movies. The film base was, and is, highly flammable, and it releases hazardous gases as it deteriorates. In movie theaters, when subjected to the high heat of arc light, the film would often burst into flame, which accounts for the large number of early movie theater fires.

Any photographic collection that contains flexible, transparent film negatives from the 1890 to 1950 period very likely contains at least some nitrate film. These negatives need special attention and should immediately be separated from other film.

Acetate negatives also have issues, but not as dangerous to human health as it is to image health. The chemical composition also breaks down with the image first crackling and bubbling, and then shrinking the film support. When acetate film is stored in a poor environment of high heat and humidity—or exposed to acidic vapors from other degrading film—it undergoes chemical reactions within the plastic support to form acetic acid. This acid causes the support to become acidic, brittle, buckle, and shrink. In turn, the acid spreads into the gelatin emulsion or into the air creating a harsh, acidic odor.

Thus if stored with stable polyester-based film, degrading nitrate and acetate negatives can and will impact its longevity as well. The types need to be well separated.

I have been a professional photojournalist for most of 50 years. Sadly, during my work with the U.S. Navy at the Naval History and Heritage Command I encountered some instances of nitrate and acetate film within their historic collections.

This is one such instance.

The photograph below was taken of an Aeromarine 39B during tests of using the airplane’s carrier deck landing skids as skis on light snow. It may be a unique image; I have found no similar photograph of an Aeromarine 39B using skids on snow. There is no date, but this type first entered Navy service in 1918 and was removed from its rolls in 1926. This print is contemporary with the original negative, thus it dates to the 1920s.

Below are scans of the original negative and, beneath it, a direct print.

It is obvious that this negative will never be printed again. It is quite likely that the print at the top is the only original one left of the negative. As it shows a fairly unique view from a tiny chunk of naval aviation history, it must be preserved—but not in the same folder as its negative!

This is a detail of the negative to better show its bubbling and cracking. I have highlighted a light portion of the film’s edge which gets narrower at the right. This is the “shadow” (it is light because it is a negative) of the grip on the film holder that held this side of the negative in place in the holder. There is another shadow on the other side of the film.

It is distressing to note that there are other instances of nitrate and acetate films within the collection. The nitrate negatives especially represent a very clear and present danger to not only the collection but the buildings and personnel around them.

Our photographic heritage is precious. Every instant of history that was recorded on film is on a piece of acetate, nitrate, or polyester that was present for that history, in the hands of a photographer who was witness to that history. Those slivers of film are the closest physical pieces we have of that history.

Our photographic heritage must be preserved!