Image change in photographic negative

Doug Harrison <lab [at] sec__state__la__us> writes

>The Louisiana State
>Archives has several large format (8x10) negatives taken on the
>scene of Huey Long's assassination.  On several of them there is a
>shifting of the negative image to a positive one...

I remember taking a photo class in college, and we did something
called "solarizing", where we would make a print onto paper from a
negative, and then briefly expose the print to daylight.  The
results were highly variable, but often the results mimicked what
you described; some of the areas looked like a positive, and other
areas looked like a negative.  Could it be that your image may have
been exposed to light at some point during the development process
and actually looked this way originally?  If so, it may not be
actively degrading.  I hope this helps, Tom Braun

Thomas James Braun
Mellon Conservation Fellow
Winterthur/University of Delaware Program in Art Conservation
(WUDPAC)
Visiting Scholar, Arizona State Museum
University of Arizona, Tucson

                                  ***
                  Conservation DistList Instance 12:94
                   Distributed: Friday, June 4, 1999
                       Message Id: cdl-12-94-009
                                  ***