I recently found a roll of some old Agfa Ortho 25 film and a roll of Orwo NP22, 125 ASA film. How old, I have no idea. Once again, Daniel Keating comes to the rescue with some experience based advise.
He wrote a nice article for diyphotography.net about reducing base fog on old, expired film.
Basically the recipe is as follows for a 300ml tank for 135 film:
- Mix a normal solution of your favorite developer
- Add 2 g of iodized table salt (or 0.2 g of potassium bromide). Acts as a restrainer to minimize fogging.
- Cool it down to 10°C (50°F)
- Develop the film for 1.5-2 times the standard time for a 20°C (68°F) development of that particular film stock. Agitate normally.
- Fix and rinse as usual
This procedure should give very fine results even with old, poorly stored film. I am looking forward to trying it out and will of course post an update blog about it.
Note: Daniel Keating’s article actually says to use benzotriazole as a restrainer. However Daniel wrote to me that 0.2 g of potassium bromide would also work.
Now, where I live, photographic chemicals are not easy to come by. But as I read in the Caffenol Cookbook, potassium bromide can be substituted by iodized table salt by using ten times the amount. In this case 0.2 g x 10 = 2 g. This is experimental, of course, but worth a try!
Daniel’s article can be read in full here: https://www.diyphotography.net/how-i-removed-base-fog-from-old-film-stocks/