Effect of ammonia vapor on photographic materials

Ivan Vanecek <vaneceki [at] vscht__cz>, on behalf of Michal Durovic,
writes

>    Do you know something about negative influence of the ammonia
>    vapor (concentration: approximately. 10 mg ammonia per 1 m3 of
>    air) to the black-white positive and negative photographic
>    materials during long exposure?

This is a matter of interest and concern to me as well, so I hope it
will be addressed by an acknowledged authority - perhaps someone
from Image Permanence Institute.  My concern stems from the practice
of making diazo images and silver images in the same facility; a
common practice in commercial microfilm labs, for example (the diazo
process employs aqueous ammonia).

I believe ammonia is a fairly potent oxidant, and I have heard,
anecdotally, of freshly-made diazo images outgassing enough ammonia
to badly fade metal silver images - rapidly - when stored in near
proximity to them.  Where diazo is made, there is often a heavy
smell of ammonia that exhaust fans never seem to be able to
eliminate.

I don't believe you stated in your query whether it was a question
of raw, exposed, or developed film (halide or metal silver), and it
might be necessary for the expert to address the issues separately.
I have not heard of any recent accelerated ageing tests using
ammonia vapor but, again, conventional wisdom has always been that
the ammonia and silver gelatin do not coexist at all well.

Chas. Stewart
Sr. Photographic Technician
Library Photo Service,
U.C., Berkeley

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                  Conservation DistList Instance 12:77
                 Distributed: Wednesday, March 31, 1999
                       Message Id: cdl-12-77-005
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