Read elsewhere about using bleach to remove the black backing from the otherwise disposed of negatives, there were some recommendations for a gel like bleach which I could not obtain locally. I found some drano gel that does a real effective job.

Walmart had Drano Max Gel, which the contents warned not to mix with ammonia, so I figured it had to be bleach based.



Put the negative emulsion side down on a horizontal surface you don't mind some bleach getting on. My darkroom sink worked for this. I dispensed about 3ml of this Drano product into the back of the negative, and spread it around with the corner of a folded paper towel. After about a minute, wipe it off with the paper towel, and rinse the work area and negative. It should be clean of the black stuff, if not, a couple more ml of Drano should be applied and process repeated.

Then I washed it in cold water. There is a somewhat caustic chemical that is dried over the emulsion. This comes off in cold water with gentle rinsing and contact. You can use your fingers, but they will dried by this process, even though you are doing it under cold water. A soft washcloth would probably be a better choice. A flat bottom tray is ideal for this part.



Here's the cleaned up negative backlit.

After a good rinse, I photoflo'd it and hang it up to dry.