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Subject: Photograph identification

Photograph identification

From: Doug Nishimura <dwnpph>
Date: Sunday, October 20, 1991
I see that Richard (Pierce-Moses) has jumped the gun on me. He correctly
points out the next logical step in identification and that is the
suggestion of an unfixed proof print.

A variety of printing-out papers were used as proofs, although the most
popular 20th century paper seems to be Kodak's Studio Proof paper (no
longer available.  According to Kodak, they had a great deal of trouble
finding suitable gelatin each year for production because of a decline
in in the number of gelatin manufacturers.   Printing-out papers seem to
be more finicky than developing out papers.  Kodak discontinued the
paper in either 1986 or 87. A substitute is available from the Chicago
Albumen Works (no longer in Chicago) imported from France.)

Printed out silver is in the form of ultra small spheres of silver,
called colloidal silver.  Modern developed out silver is in filaments,
like bundles of steel wool.  The size and shape of particles greatly
influences the properties of a particle.  Thus filamentary silver tends
to appear neutral black.  A smaller silver filament produces the
browner image associated with "warm toned" papers.  Even smaller
particles look *red*, orange or yellow.  Modern prints that have been
attacked by oxidant pollutants turn orange as similar colloidal silver
is formed (usually starting from the edge of the print.)

The light sensitive salts are, as Richard pointed out, still present in
the paper and thus exposure to light will cause further degradation of
the image. In theory, fixing and washing will stop the problem (but not
reverse it). However, there is great risk that plunging this object into
aqueous solutions will cause significant damage to degraded gelatin. (At
the worst, you'll lose it completely.) There is also no way of telling
the condition of the gelatin by just looking at it (a lament that I've
often heard from Debbie Hess Norris.)

The best thing to suggest is to store it in the dark.  Severely limit
access to it.  If you absolutely must, then examine it only under very
limited light. I remember looking at similarly (light) delicate images
at HRC.  We had to turn off the lights and use only the light getting in
from an adjoining area. (A wise precaution.)

I'm also adding a plug to Jennifer Porro's note about the new RLG
publication. I've seen a copy of it already and it's a *great* book.
(No Jim Reilly isn't a member of this dist. group and won't see this.
:-) )
    **** Moderator's comments:   Not for want of an invitation.  Sigh.


                  Conservation DistList Instance 5:25
                 Distributed: Sunday, October 27, 1991
                        Message Id: cdl-5-25-002
Received on Sunday, 20 October, 1991

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