Pink fingerprints on photographic print

I have seen a few pink fingerprints on B&W prints before, but I've
never had to define the source.  Most of the folks I have talked
with have only seen a few, or no, pink fingerprints on B&W prints.
Most of the fingerprints I have seen are in a silvered-out deposits,
possibly a negative fingerprint where the oils prevented
silvering-out locally.

The print under examination is a non-Kodak fiber-based paper with
neutral gray tones, made in 2001.  While magenta (pink) fingerprints
on chromogenic prints (loss of cyan and yellow dyes) is common, this
print is a B&W image.

Does anyone have something to add to the following information?

In the article: Topics In Photographic Preservation, Vol. 5, 1993,
pp 8-13: Hendriks and Krall, "Fingerprints on Photographs," the
source of classic yellow to white fingerprints on B&W prints are
defined.

Hendriks and Krall say the NaCl/KCl in the fingerprints produces
bleaching of the image, often with yellow present.  They say the
yellow is due to colloidal silver, which is yellow.  My comment is:
colloidal silver is finely divided silver particles, for the
particle sizes found in B&W prints an negatives, this is yellow.

The pink color could be a slightly larger AgCl, or Ag2S, colloides
on the image silver.  Red light has a large wavelength than yellow.
Particle size interference with white light is one of the probable
sources of the color manifested due to particle size.

Hendriks and Krall say developer-based fingerprints show darker
fingerprints, while fixer-based fingerprints shows yellow silver
sulfide.

I have produced a pink discoloration in my white lead discoloration
experiments many years ago.  I noticed then that silver tarnish and
white lead discoloration show similar color progressions.  The pink
observed was due to colloidal deposits of sulfide (from H2S,
hydrogen sulfide gas) on the white lead substrate.  Normally, the
discoloration would be red, but a thin deposit was pink.  The tonal
range went from: yellow, red, brown, warm black to cool black with
tinges of blue.  The first stage, yellow, was often fleeting and
temporary.

Is there some non-RC type B&W fiber paper used by commercial
photographers in 2000-2002 that would be markedly different from
those in the past, i.e., smaller silver particle size?

Tim Vitale
Paper, Photographs and
Electronic Media Conservator
Digital Imaging and Facsimiles
Still Film Migration to Digital
Preservation and Imaging Consulting
Preservation Associates
1500 Park Ave
Suite 132
Emeryville, CA 94608
510-594-8277


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                  Conservation DistList Instance 19:9
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