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Subject: Reddish photo id

Reddish photo id

From: Sue Bigelow <sue_bigelow>
Date: Thursday, October 17, 1991
     Here are some further details about our reddish mystery photo for
all those kind people offering assistance.

     There are no obvious signs of silver deterioration.  I don't see a
baryta layer, and since the edges have been trimmed, it should be easy
to spot.

     I have compared it to our old sample book "32 Varieties of Autotype
Pigment Papers"  (Carbon Prints), and the surface does look similar;
small flecks are even apparent, which could be undispersed pigment.  I
initially didn't think it was a carbon print because there is no
apparent surface relief or crazing in the binder, and there are two
colours.  The image areas are black and the highlights are the brilliant
"safety -vest" orange-red, although the image is warm, as though it is
also covered with orange gelatin.

     Now, my suspicions are that it is a carbon print, and that the
black image was printed first and overlaid with a continuous layer of
orange-pigmented gelatin, which would explain the absence of relief.
Quite the strange effect, especially in a portrait, but that's art.

     My only remaining confusion is that I expected my spot test on the
edge to swell if the binder is gelatin.  Perhaps it has been so hardened
during processing that swelling is not noticeable.

                                   Sue Bigelow
                                   City of Vancouver Archives 

                  Conservation DistList Instance 5:24
                 Distributed: Sunday, October 20, 1991
                        Message Id: cdl-5-24-005
Received on Thursday, 17 October, 1991

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