Bleaching and redevelopment

Bleach and redevelopment:  With regard to ethics, Klaus has only
suggested B/RD for archival materials.  Obviously with the uncertainty
of success (and the potential for disaster), he recommends that if a
duplicate print (same process, same vintage) exists (that is expendable)
that the B/RD be tested first.  The test not only required the testing
of the effectiveness of the procedure, but also that the stability of
the gelatin be monitored during the test procedure using a "swellmeter".
The swellmeter measures gelatin stability by virtue of the amount of
swelling occurring in solution. Note that it is not a perfect measure
since a hardened gelatin can swell much more that an non-hardened
gelatin before it disintegrates.  This is not an "off-the-shelf" item
and must be custom made.  To my knowledge, the one I had commissioned
for the archives was the last one built in the world. At that time there
was one in France and one at Kodak in Rochester.  The cost then (in
1983) was $25K (Canadian).  Since it's not mass produced, I suspect that
it costs a lot more to make now.

Think about the risks too.  Unique objects may be destroyed. I don't
remember if I mentioned it, but if the silver filaments have broken- up
too far, you may not only not recover the original density, but the
image that you had may also disappear.  In an early test, we used a
printed-out image to simulate 1) colloidal silver and 2) total loss of
filaments. The image disappeared almost totally in the bleach and was
never seen again. Remember too that you will not be in charge of the
object forever and that no curator can guarantee that a "successfully"
treated image will not appear on the market.  In addition, does the
institution control the purpose of the object?  Case in point: The
Canadian Archives bought a large amount of Karsh's work.  Before they
bought them, the objects were considered to be works of fine art.  Now,
because the photographs belong to an archive (collecting items of
historical value), are the prints now archival objects (information
only) or have they retained their status as "fine art"? All of these
were issues that came-up during the research of this chemical treatment.
In fact, all chemical treatments are in question.  For example, there
are many processes for chemically removing the silver mirroring on
photographs, but should it be done?

-Doug

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                  Conservation DistList Instance 5:16
                  Distributed: Monday, August 26, 1991
                        Message Id: cdl-5-16-004
                                  ***