Re: archivalness of gum
This is interesting. I've always wondered on what basis it is said
that carbon prints are the most stable kinds of photographic prints.
So I gather that it's based on this galvanic series below. I can
see how that would work for pure charcoal or graphite, but when it's
held in a crosslinked polymer matrix, does it have the same
properties? I don't know, I'm just asking.
At any rate, if archivality is determined by the pigment rather than
the colloid, then I don't understand Gawain's statement about carbon
being more archival than gum (assuming both using same pigment of
course). Or is there something about crosslinked gelatin that's more
archival than crosslinked gum? If you have any research about that,
Gawain, I'd sure like to know about it, thanks.
Katharine
On Dec 20, 2007, at 11:33 AM, Sandy King wrote:
Diana,
Metals are classified by a scale known as the galvanic series,
which determines the nobility of metals and other substances such
as graphite (graphite is actually a polymorph, as is a diamond, of
the element carbon). According to the galvanic series, the order is
1) graphite, 2) palladium, 3) platinum, 4) gold, 5) silver, 6)
titanium and so on to the stainless steels and bronzes.
So it is true that platinum is more stable than gold, but palladium
is more stable than platinum, and carbon is more stable than
palladium, platinum and gold.
Many people have observed that when a platinum print remains in
contact for a long period with covering piece of paper there may be
a partial transfer of the image from the original print to the
other paper. To my knowledge this has not been observed with gum or
carbon prints.
Sandy
At 2:14 PM -0500 12/20/07, Diana Bloomfield wrote:
Well, I was told at one time that platinum is more stable than
gold-- consequently, at least one of the reasons it's the most
archival. (The other reason is probably that it's so ridiculously
expensive that we have to convince ourselves that it has to be the
most archival, if not the most beautiful, in order to justify the
cost.) Whatever-- I'm thinking I'll still go with the platinum-
is-more-stable-than-gold story whenever some museum curator asks
me that question-- that is, until I learn carbon printing, or
perfect gum printing. :)
Diana
On Dec 20, 2007, at 1:27 PM, Sandy King wrote:
Diana,
In fact gum (and carbon also) are probably more permanent than
platinum, assuming one uses light fast pigments. Carbon pigment
is totally inert, and a print that consists of carbon pigment in
a hardened layer of gum arabic or gelatin would be limited in
terms of life more by the support on which the print is placed
than the image itself.
Sandy King
At 12:03 PM -0500 12/20/07, Diana Bloomfield wrote:
Hey Chris-- Isn't platinum the most archival process? At least,
that's what I always tell people. I'm sure I read that
somewhere. I did have someone ask me an interesting question
recently that I never thought to ask anybody-- but I had made a
gum over platinum print, and this person suggested that by using
gum over the platinum, I was harming the platinum in some way--
or, at least, somehow removing the archival nature of the
platinum, since-- this person said-- gum isn't archival. I
think this person was only *assuming* that gum isn't archival--
really didn't know for sure-- but I thought it was an
interesting question.
On Dec 20, 2007, at 10:30 AM, Christina Z. Anderson wrote:
Good morning all!
This may be a question for Gawain Weaver as I don't know who
else on the list is "in the know".
I have always read/thought/been told that gum along with carbon
is the most archival process there is.
I heard a comment the other day from a museum curator who said
it was "not the most archival process".
Now, I know that certain pigments used in the past were NOT
lightfast. Gamboge, alizarin crimson, etc. were pigments that
faded thru time we now know and the watercolor painters know,
too. Also, I know that if you leave the dichromate stain in as
a darker brown addition underneath the gum layer, through time
in sunlight that image will fade to gossamer green and
therefore the print will lighten **somewhat** (found a cute
little article on that fact about gum prints "fading on the
walls of exhibitions"). But if using archival pigments and
also taking into account the slight tone difference of an added
dichromate stain now that we are not cooking our prints with
heavy 100% sodium dichromates, etc.,, aren't gum prints really
archival?? Anyone have gum prints that have not lasted? I've
seen Kuehn's and Demachy's but unfortunately, photography is a
relatively new art and thus we only have about 170 years of
evidence.
Unfortunately, I left my only conservation book (thanks,
Gawain) at home and I am in FL for 3 wk--writing my gum book at
least!
Chris
Christina Z. Anderson
Assistant Professor
Photo Option Coordinator
Montana State University
Box 173350
Bozeman, MT 59717
406.994.6219
CZAphotography.com
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