Separate colour negative strips when emulsion sides stick to each other

Question

I’m trying to recover old photo memories by digitising 35mm negatives.

Unfortunately the negatives weren’t properly stored, and in most cases some humidity made all negatives to stick to each other.

Sometimes the emulsion side of the colour negatives are sticking to each other, and I wonder what I did wrong when soaking them in plain demineralised water (which seems to be the usual approach) in the hope to separate them.

I noticed that for a given film roll, after 24 hours the water turned orange and that the water felt lukewarm (exothermal reaction) and that some emulsion either bleached or vanished, permanently ruining the affected colour negatives. For instance, in places where the emulsion wasn’t covered (e.g. through sprocket holes from the other negative strip), I now have “burn marks” where the emulsion has been washed away or is completely gone. Sometimes even in places still attached to eachother in the middle of the strip…

What went wrong? Is this a sign of an improperly developed film roll? Can I avoid such damage?

I am now stuck in the color negative unclinging process until I find a proper way to safely uncling the remaining negatives (equivalent of 100+ rolls).

Answer 1

Sorry for your loss -- You likely cannot unstick these negatives and not have damage. The last chemical step of the C-22 and early C-41 process was a brief soak in a wetting agent (PhotoFlow) or equivalent laced with formaldehyde. The formaldehyde hardens the emulsion plus it is a biocide that retards fungus and bacterial growth that thrive on the gelatin emulsion and the image comprised of organic dyes.

You should try adding a pinch of dishwashing detergent to your soak. You might add a pinch of Bactine wound cleansing liquid if you want to store them after you make your scan.

The emulsion is gelatin based and it will dislodge if the soak is more than a few hours. As to the color change, the dyes are organic and they change their color easily when wet, when the pH changes, or when the temperature changes. likely when the film dries, the original colors will return.

Answer 2

I found out that after a while (a few hours) in demineralised water, the film strips can sometimes be peeled apart a bit. If this happens, do not rush. Make sure the place where both film strips separate remains wet.

If you need more than gentle force, or if the strip makes a cracking noise when separating, soak the strip a bit longer as it may be a cue that the emulsion layer might be detaching.

Check every hour for progress.

If you have wetting agent at hand, the process might even speed up as water will more easily reach the emulsion bond between film strips. Add only 1-2 drops to your bath.