BetterPhoto Q&A
Category: New Answers

Cleaning film negs and slides

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January 25, 2008

When it comes to cleaning film one chooses a solvent cleaner that is water free. This is true because the emulsion side is composed of gelatin. When wet, gelatin swells and then shrinks down as it dry. Non-uniform wetting causes stress patterns commonly called drying marks that are irreversible. Additionally the gelatin emulsion when wet becomes soft and easily scratched.

Water washing is however permissible you can even use a dilute dishwashing detergent. After washing rinse in running water for 5 minutes then using a soft sponge remove excess water. A product known as Kodak Photoflow is a wetting agent commonly used as an after wash treatment. Fotoflow prevents water beading reducing the likelihood of drying marks. Only water wash if you are familiar with wet film handling technique. You should not attempt to wash mounted slides. The mounts can’t tolerate water and likely water will be retained under or absorbed by the mount material. As a mounted slide dries, water will slither out of the mount covered areas thus producing drying marks.

If the film is precious to you, purchase film cleaner from a camera shop or photo supply house.

If you are adventures you can buy denatured alcohol at the hardware store.
As an alternate in some liquor stores you can buy “ever clear” a near 100% (200 proof grain alcohol). These are OK film cleaner however alcohols are flammable and slower to evaporate than other solvents.

One of the best solvents for film is Naptha. This is the lighter fluid sold by Ronson and others. It is highly flammable. Hydrotreated Naptha is excellent and non-flammable.

Most of the solvents at the paint store will work fine.
Skeptical? You can try some one or two on less valuable film

Use soft clean lint-less cloth like a well used and laundered T-shirt.

Note: Old film stored in high humidity promotes bio-growth feeding off the gelatin which is made from animal hides. Alcohol is a bio killer.

On second thought “go and buy your film cleaner”.

Alan Marcus, Anaheim, CA (dispenses marginal technical gobbledygook)
ammarcus@earthlink.net

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January 25, 2008