The Sub Club

FILM SCRATCHES

Scratches on the film can have several causes and, consequently, may require several solutions. If you use factory-loaded cassettes, the common culprit is dirt or dust in the camera. It doesn't take much -- just a speck can get lodged in an inopportune place and leave a scrape the entire length of the roll of film. If you reload your own cassettes, you'll have an additional enemy -- the cassette itself. Dirt can get lodged in the cassette felt and cause roll after roll to be scratched. The more times you reuse the cassette, the more likely this is to happen. To make matters worse, if you use an old metal cassette, there may be some rust spots on the inside of the cassette that scratch the film.

And you can get film scratches from other sources as well. If you slit your own film, the film slitter may be the problem. The sliding block or felt might harbor a small piece of dirt. And even after processing the film, you need to be careful. If you failed to add a hardener to your fixing bath, the film is more likely to get scratched, and if you store your negatives loosely, they are more likely to pick up dirt that can cause scratches in the enlarger.

That should give you a general idea of the many ways that an innocent little negative can become the victim of a ruthless scratch agent.

How you remove a scratch depends on where the scratch is. First, take a close look at the film. Is the scratch on the emulsion side or on the base side? You can usually determine this by casting a light at a strong side-angle on the film. This helps the scratch stand out. If you still can't see it, lightly run a sewing needle across the width of the film in between the frames. You might be able to feel a slight bump on the side with the scratch.

If the scratch is on the base side, you are in luck. These are the easiest to remove. In fact, Edwal makes a product designed for these types of problems. It's called No-Scratch and is cheap and available everywhere. It comes with complete instructions, but basically you apply a small bit of No-Scratch to the scratch and it fills it in with a clear fluid similar in density to the film base. The trick is not to use too much. In an emergency, you can even use a bit of oil from the side of your nose or refrigerator. Just remember, in this case, less is more.
If the scratch is on the emulsion side, don't give up hope. These are more difficult to remove but sometimes worth the trouble. The problem here, unlike base-side scratches, is that part of the image is actually gone. In dark areas of the scene, this may not be a problem since those sections are clear on the negative anyway. But in highlight areas of the scene, where the image on the negative is dark, a dark line will appear on the print where the emulsion has been scratched away. The two standard approaches are retouching the negative and retouching the print. Retouching the negative is best, since it only has to be done once, but is very difficult with tiny submini negatives. It basically consists of filling in the scratch with graphite from a pencil. The darker the surrounding area, the more graphite is added. Retouching the print is similar, but must be done for each print and requires retouching over a larger area. You can either scratch out the dark line with a special tool or bleach the dark line until it approximates the surrounding area. Then, if needed, various B&W and color dyes can be applied to make a perfect match. If you plan on using either of these approaches, it's best to buy a book on retouching.
And no matter which side of the film happens to have the scratch, you can minimize it's affect by using a diffusion enlarger.

After removing the scratch, try the following methods to avoid future scratches:

Always clean out your camera before loading it with film. A bit of pressurized air and a camel's hair brush is best, but even a good blast of air from your lungs is better than nothing. Pay special attention to the camera's film pressure plate.
Do not reload your camera in a dusty or windy area.
Always clean out your film cassettes before reloading them. Pay special attention to the felt and consider retiring your old cassettes if you have that option.
Only reload your cassettes in a dust-free area.
Always keep your reloaded or empty film cassettes in their film cases or a plastic bag.
Regularly check the insides of metal cassettes for signs of rust. If any appears, carefully remove any large bits with a file or sandpaper -- making sure to keep the filings away from the felt! Then cover the offending spot with several coats of top-quality, rust-inhibiting, black, glossy, enamel, oil-based paint. Let the paint dry in a dust-free area for at least a week.
Always clean your film slitter before use and make sure to use it in a dust-free environment.
Set up an air cleaner/filter in your darkroom.
Use a hardener when you process your film.
Store your negatives separately in a soft plastic holder.
Keep your enlarger and negative carriers free from dust.
Keep you Edwal No-Scratch (or your nose) close at hand.

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