U of S | Mailing List Archive | alt-photo-process-l | Re: Image transference; was - archival ness of gum

Re: Image transference; was - archival ness of gum

From: Don Bryant <dsbryant@bellsouth.net>
Subject: Image transference; was - archival ness of gum
Date: Fri, 21 Dec 2007 17:01:24 -0500

> After returning from one such trip I was surprised to see
> the out line of the Post-It note in the middle of an exposed
> sheet of 8x10 Tri-X after processing.

Do you mean the outline of the piece of paper, not the writing
on it?

Silver-gelatin emulsions, especially those that are designed
for high radiation/light sensitivity, have sensitivity to
mechanical pressure. This is most carefully controlled in
radiographic films because those films are routinely handled
very rapidly, often in roller transport machines, and any sign
of pressure mark may lead to serious misdiagnosis.

On the other hand, pictorial films made by manufacturers
without the latest technologies may suffer from this problem
more easily. Some films may show pressure fog if used in a
camera with very tight film feeding mechanisms and with many
right angle bending (such as Rollei TLRs).

I'm guessing that you packed the film affixed with Post-It
tightly and perhaps for a longer period of time when you saw
the imprinting on the developed image.

Ryuji Suzuki
"Patriotism is the last refuge to which a scoundrel clings."
(Bob Dylan, Sweetheart Like You, 1983)