What is this?

Victor Engel said:

So in summary so far:

• Fungus
• Chemical reaction
• Static electric effect

I think the last option can be eliminated. The other two are what I suggested in the first place. How can we distinguish between the two? In both cases, growth begins at a point and expands into areas where there is more material to supply the growth. The growth ceases when the supply is exhausted. This produces the same effect for both fungal growth and chemical growth.

In the case of fungus, growth starts with a spore. Either the spore landed on the film during manufacture or processing or else contaminated the film later. In the latter case, it would likely encroach from the edges of the film.

If it were chemically based, the source would likely be the emulsion itself, so I would expect the distribution to be even throughout.

Does anyone have samples of similar patterns where the source is known? Maybe we can compare images.

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mamallama said:

It is not a mystery. Fungus growth on processed film has be a well-known and much discussed problem during the days of film. Someone had suspected, then, that several eras of Kodachrome was particularly prone to certain types of fungus. I got some on my old stored Kodachrome and Ekachrome slides. Likely there's some on my old negatives as well, but I don't go back to print them.

Fungus is like bacteria and yeasts; there are virtually unlimited varieties. Kodak has known of the problem for some time. Here's an old Kodak Bulletin talking about Fungus and Film:

http://static.photo.net/attachments/bboard/007/007tlK-17401484.pdf

If you want more information, just Google, "Film and Fungus".

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