I rarely develop old found 35mm films.
The reason is simple: they aren't holding latent image at all.
Nothing compared to rollfilm, which is very good in standing ordeal of time.
Extreme fog is common on 35mm and other cassette-type films.
Despite this I recently tried to develop several 35mm cassete film in very cold and active developer.
I also did clip-test.
All of these helped to resque some of the images from these rolls.
The images in this post are from Kodachrome, supposedly exposed in late 60s or early 70s, but exact time frame is unknown.
I received this one from camera collector based in Connecticut as part of small collection of old exposed rolls.
Kodachrome is color slide film, I developed it as black and white:
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There were many on the roll, I have not scanned all of them.
They were all alike: strange, holgonautic and haunting.
Technical details:
clip-test in HC-110 Dil B at 50F/10C
Developed roll in HC-110 Dil B for 5 min at 45F/7C
Manually wiped out rem-jet anti-halation backing