An Unexpected Leak

That's like a chapter title from a bad spy novel (or maybe a bad plumber's manual). Anyway, I just thought I would make a brief post to show the dangers of using thin base films. Generally we think of film as just emulsion layered onto a sheet of flexible thin plastic that is then cut, perforated (optionally) and rolled. I realized when I started developing my own film that the 'base' support is quite different for different films. Certainly color films are different than black and white. The support material on most color films is some shade of orange, while on black and white films it is either clear or a neutral grey. But what I hadn't really thought about was that the support material is different thickness depending on the film and it's intended purpose. Movie film needs to be thick and strong enough to stand up to the forces that are pulling it through a movie camera. Still camera film can be thinner so that more exposures can fit into a standard roll. Then you have specialty films like Kodak Plus-X Aerecon II. I have written about this film before, but I don't think I have mentioned much about the consequences of rolling it into standard 35mm cartridges. Standard cartridges have a little fuzzy piece of fabric around the inside of the opening where the film leader comes out. That serves dual purposes. First, it keeps the metal edges of the canister from scratching the film. Second, it acts as a light seal so that light does not enter the canister through the slit and fog the film. Well that's all fine if your film has a thick base support layer and it takes up all of the space between the two light seals on either side of the slit. However, Aerecon II was intended for aerial reconnaissance photography. When flying long distances, it is important to economize on weight so that your fuel will last for the entire mission. So the film was made with a very thin base so that a big roll of a few hundred or a thousand feet would weigh significantly less than it's consumer counterparts. This means that the film does not fill up the space between the light seals in a standard 35mm cartridge and if you are not careful, the light will come in and make nice stripes on your beautiful pictures. So let this be a warning to all of you shooting thin base films. Load and unload in the DARK! Not the shade, and not 'subdued light'... the DARK. Cautionary photos to follow.