[filmscanners] Re: Mold (was Modern photography...)

["Carlisle Landel" <clandel@adelphia.net>]

At 2:20 AM -0700 5/18/05, Arthur Entlich wrote:
>OK, how about this... maybe the PEC is responsible

A word about mold.

In my real life, I am a research biologist.  In fact, I know a lot
more about mold than I do about scanning film or slides (but I'm
trying to learn!).  ;)

For the mold to grow, you need to inoculate some suitable substrate
with spores--these will need water and food.  Molds will grow on
almost anything, including film, given some water.

The thing about spores is that they are very, very tough to kill.  It
is perfectly plausible that your batch of negative cleaner was
contaminated with mold spores.  There was a somewhat infamous case a
few years ago in which mold spores contaminated a lot of mineral oil
used to overlay culture media used by laboratories culturing embryos
(both human and animal)--suddenly lots of labs were finding
contamination of their cultures.  Once everyone compared notes, the
source was identified as this one particular lot of "embryo
certified" oil.  Alternatively, maybe you simply were working in a
moldy environment, and this is why all your "favorite" negatives got
contaminated as you were taking them out and working with them.

Spores still need moisture in order to start growing, so all the
suggestions for storing your negatives in dry conditions
(de-humidifiers, silica gel, etc.) are exactly correct and will help
tremendously.  Cold storage would also help, of course, though you
then run into a problem with condensation every time you bring your
negatives out of the freezer.  That is to say, one (often ignored)
source of moisture is condensation from the atmosphere onto items
removed from cold storage.

If you have a mold problem, you should probably clean off the
contaminated negatives as soon as possible, as the mold are busily
digesting them--otherwise the damage will continue to accumulate.  A
real film conservator might weigh in with the accepted professional
solution, but in the meantime I'd suggest first soaking them in a
solution of 70% ethanol, which should kill the vegetative (growing)
cells (but won't kill any spores) and shouldn't harm your negatives.
Then you can try your favorite negative cleaner to get the mold off.

Toss the sleeves that contained the contaminated negatives, as these
will be a source of more mold.

And then store everything in dry conditions.

Good luck,

Carlisle

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