Film storage nightmare...
I picked up a 1000 foot spool of 5" Kodak 2402 aerographic/aerial Plus-X on eBay. Many of my lens/camera projects in the works are focussed on this film.
Kodak was kind enough to send me a roll of 35mm pre-exposed test strips of this film, although it presents it's own irrelevant conflicts.
So, all my film is in a little refrigerator in the garage. During cold winters, I unplugged it thinking it was pointless to run when the outside temperature was so cold. I forgot to turn it back on until fairly late in the spring this year. I found in the freezer section that the 35 mm bulk spool of test strips was moldy and rusty. I dumped the box and hoped for the best on the inside contents. Not having a darkroom, today I took it to my local lab that humors me and asked if they'd run some strips to get some soup time benchmarks. They didn't see much point based on the number of variable I'm likely to introduce with my own exposure EI, etc.
The inside of the can was as nasty as the outside. The film was stuck to itself but did de-reel. Interesting as it was still taped & never opened.
I sure hope the 1000' spool didn't go down the toilet as well...It was at least not in a condensated area like the freezer portion.
Can anyone reign in the panic with some perspective on what ill effects there may be assuming the grossest ones involving mold didn't occur, like what ferrotyping is or looks like. I hear this is pretty stable film, within reason, in less than ideal storage (like unrefrigerated).
Ferrotyping is just what you saw with the test strips -- film sticking to itself after the emulsion has been wet or damp in the roll.
Even if ferrotyping doesn't occur, you may find that dampness has redistributed sensitizing dyes in the film,which would render it impossible to count on even exposure across a frame. The only way to know, however, is to cut, expose, and process some of the film. Generally, if the first few feet is okay, the rest of the roll will be as well.
Photography has always fascinated me -- as a child, simply for the magic of capturing an image onto glossy paper with a little box, but as an adult because of the unique juxtaposition of science and art -- the physics of optics, the mechanics of the camera, the chemistry of film and developer, alongside the art in seeing, composing, exposing, processing and printing.
A small addition to what Donald has already said: ferrotyping of damp film has the appearance, when dry, of glossy patches of emulsion, exactly like a ferrotyped ('glazed' in the UK) print, but usually only in patches.
What is strangest of all was the piece of test strip they handed me and said 'look, it has hardly anything at all on it', which prompted me to discard the whole cannister (test strips only). That was the final insult.
In hindsight I should ask if they ran that film through processing or if they thought I handed them a spool of test wedge...just to make sure we were on the same page..because the piece they handed me looked like undeveloped film...just opaque gray...something stinks here...I remember taking a piece of this film and rinsing it under hot water...I don't know what inspired me to do that, but most of it came off, including anti-halation dye, etc. What they handed me yesterday looked pretty healthy still, like unprocessed.