Visible images on non-developed film left out for hours

[gavjenks]

I botched loading some film and decided it would be too much of a scratch potential to use, but instead of throwing it away, just tossed it on my table, a couple sheets of it.

Next day, the part of the film that was exposed to my room lights is about half as lightly toned as the part that was covered by the other sheet.

I am currently running an experiment where I have a still life set up with a very bright bulb and my camera just aimed at it with a piece of film exposed and am going to leave it until tomorrow and see if I get a legit detailed image.



But in the meantime, I'm sure many of you are already aware of what's going on. So I thought I'd ask... what's going on? Is this a secondary chemical process of some sort? Chemicals breaking down into something else? Or what?

[Sevo]

This is the primary process - silver salts are reduced by light, development merely amplifies that. As used by the early pioneers of photography, and in printing-out paper. With enough patience (and if you are satisfied with very mediocre results from a substrate tuned to development) you can do away with developing, and expose the film (or better, paper) until black. You still have to fix, or the rest will blacken in display.

By the way: The effect on (some) film within a few hours in room light is merely fading of sensitizer dyes (as obvious by the positive action, the film getting lighter rather than darker in the exposed areas), if you'd fix at that point, you'd wash out that dye and be left with a very faint (almost invisible) brown negative silver image. It takes much longer for the silver to blacken to a visible negative - hours to days in full sunlight (or under a strong UV source), weeks or months indoors.

[AtlantaTerry]

When I was a young boy we used to do something similar at summer camp. The instructor gave us contact printing frames and B&W photo paper. We would put leaves and other stuff on top of the paper then clamp the glass in place. After a while the image was set and we would give the paper to him. He took it home to fix and wash.