Super 8 film, although now long obsolete, is where many people's childhood memories are stored. Released initially in 1965 by Kodak, Super 8 was an 8mm film format that used plastic cartridges of film to simplify the loading and unloading of film from the video camera. Now that Super 8 is a technology of the past, preserving existing Super 8 films is especially important. Regular cleaning with the proper chemicals is essential.
Film Cleaning Chemicals
It's possible to buy dedicated film cleaners. These include FilmGuard, FilmRenew, and Vitafilm. FilmGuard is designed to lubricate commercial films passing through dirty projectors and will not do a great job of protecting film over the long term. Both of the other products work better for consumer film, with VitaFilm evaporating somewhat faster (and thus allowing you to clean your Super 8 film more quickly.
Kodak once recommended methyl chloroform, but this has been taken off the market due to the damage it does to the ozone layer. If you do find some, it should only be used in a well-ventilated space. A substitute and more available chemical is perchlorethyline; however, it's unclear as to how dangerous this is to human health. With both chemicals, gloves, a mask, goggles, and a well-ventilated space are essential. A much safer idea is to use standard rubbing (isopropyl) alcohol, which will clean film adequately without safety or ventilation concerns.
The simplest way to expose the film to be cleaned is to place the cartridge in a projector, and then clean it as it goes by. This is awkward, though, as most projectors don't have a great deal of space to access the film, and cannot be spooled manually. If you can, buy a Super 8 film editor; these can sometimes be found online or through local film clubs. This piece of equipment will let you spool the film from cartridge to take-up reel manually, with space to clean it as it goes by.
Film Cleaning Method
Moisten a soft, lint-free cloth with the cleaning chemical of your choice, then fold it around the film and spool the film slowly through the cloth. You must spool it slowly enough that all the chemical has dried before the film wraps around the take-up reel. If you don't, it will stick to itself. Change cloths if the one you are using is getting visibly grimy, and then wipe the film down with a lubricant such as .59 grams of pentaerythritol tetastearate mixed into a litre of solvent such as isopropyl alcohol.
Don't clean film too often, as it will weaken and discolour it. Once every few years should be enough. It's more important to thoroughly clean all the projecting equipment you use the film with, since that equipment will damage the film as you play back the recordings on it.