All,
Most interesting article. It really plays very nicely into this discussion and provides evidence to the theory of catalytic action of platinum that I just mentioned. I would postulate that the "ghost image" is deteriorated paper substrate. Why there is a facsimile of the image formed? Well, the catalytic action of platinum is proportional to the amount of metal, that is darkest part has most metal and would exhibit most catalytic action. That action would be exhibited both on paper that is in contact with the front of the photograph or on the substrate of the photograph itself. This can be seen as a ghost on the back of the print. The author has found evidence of both. I would postulate that the faint image is not a transfer of metal itself.
The catalytic action of platinum is most likely oxidation of pollutants like SO2 or NOX to strong acids like sulfuric and nitric, which in turn damage the paper base, but other catalytic mechanisms could be at play as well.
This would also suppot M. Ware's notion that chrysotypes would be most permanent metal based photographs as gold is very stable and does not posses any catalytic properties.
Coming back to the stability issue. Carbon pigment is very stable and does not interact with paper or any components of the photograph, be it gelatin, gum or paper. My vote would be to consider carbon pigment based prints as most stable.
Carbon black as well as red iron pigments were used in cave paintings thousands of years ago. Take that for stability.
Marek Matusz
> Date: Fri, 21 Dec 2007 10:10:49 -0500
> From: dhbloomfield@bellsouth.net
> Subject: Re: archivalness of gum
> To: alt-photo-process-l@usask.ca
>
> Thanks for that link, John. I love Malin's site, but certainly
> missed this (having spent most of my time just looking at the
> pictures). ;)
>
> Diana
>
>
> On Dec 21, 2007, at 7:43 AM, john@johnbrewerphotography.com wrote:
>
> > Hi Diana
> >
> > An article on the ghosting of platinum can be found on Malin's site
> > here: http://www.alternativephotography.com/articles/art063.html
> >
> > Best
> >
> > John.
> >
> > www.johnbrewerphotography.com
> > ----- Original Message ----- From: "Diana Bloomfield"
> > <dhbloomfield@bellsouth.net>
> > To: <alt-photo-process-l@usask.ca>
> > Sent: Friday, December 21, 2007 3:53 AM
> > Subject: Re: archivalness of gum
> >
> >
> >> Hey Chris,
> >>
> >> Well, that's where you and I differ (the belief that carbon and
> >> gum is the most archival-- instead of platinum). :) Honestly,
> >> today is the first time I've ever heard the news that platinum
> >> isn't the most archival. That said, the "ghosting" that you and
> >> Sandy both mentioned-- I'm curious-- how much time does that
> >> take to occur (a week? decades?), and under what type of
> >> circumstances, or does that not matter? I'm also curious -- did
> >> your curator mention what he/she believed to be the most archival?
> >>
> >> Thanks, Chris.
> >>
> >> Diana
> >>
> >>
> >> On Dec 20, 2007, at 10:26 PM, Christina Z. Anderson wrote:
> >>
> >>> Judy, Gawain,Diane, etc.
> >>> Diane--platinum ghosts onto paper it is in contact with so it
> >>> loses some of its precious metal in storage I remember Dusan
> >>> Stulik telling us/showing us at an APIS. In fact, this is a
> >>> method to determine whether a print is a platinum one or not.
> >>>
> >>> I was always under the assumption that carbon and gum were THE
> >>> most archival of all processes. That is why this curator's
> >>> comment surprised me so much. I have yet to come across any
> >>> discussion of degradation of gum prints except for the one
> >>> article talking about the fading of the dichromate image within
> >>> the gum print. This can be easily demoed by leaving a gum print
> >>> in the sun for an afternoon, half covered by something for
> >>> comparison's sake.
> >>>
> >>> Judy, gum over platinum has been done since 1902, invented by
> >>> Herbert Silberer, an Austrian.
> >>>
> >>> Holland Day did it as did quite a few other Americans, and I
> >>> have never heard that wasn't archival either. In fact, one
> >>> author said the French were known for one coat gums, the Germans
> >>> for multiple coat gums, and the Americans for gum over platinum.
> >>>
> >>> Gawain, I have seen some original Kuhn's at A Gallery of Fine
> >>> Photography that were perfect, and just hanging on the walls
> >>> there like no big deal. He was a master printer of the multiple
> >>> gum, as was Demachy...but the bug thing has got to be an issue
> >>> and I wonder if use of formaldehyde for hardening gelatin gives
> >>> the benefit of preserving it from bugs...oh, the cracking in the
> >>> dark thing...I wonder if sizing would contribute to that
> >>> phenomenon?
> >>>
> >>> So what I have deduced, after this discussion to date, is gum is
> >>> what I think it is and I wasn't whistling Dixie. I wonder if
> >>> Wilhelm has studied gum stability???
> >>>
> >>> Chris
> >>>
> >>>
> >>>> And also, by the way, gum over platinum is an historic process
> >>>> -- if
> >>>> memory serves (which I can't promise, MEMORY is NOT archival) Paul
> >>>> Anderson (heh heh) did it, but also I think Heinrich Kuhn, among
> >>>> others. I
> >>>> believe it was fairly well known... Then again there were many
> >>>> kinds of
> >>>> "platinum" including a commercial "platinum paper" -- who was the
> >>>> Englishman who swore he'd stop photographing when that paper was
> >>>> discontinued? He had the same name as a photo historian or
> >>>> other pioneer,
> >>>> but ... as noted, this memory is not archival.
> >>>
> >>>
> >>
> >>
> >>
> >>
> >>
> >> --
> >> No virus found in this incoming message.
> >> Checked by AVG Free Edition. Version: 7.5.503 / Virus Database:
> >> 269.17.5/1190 - Release Date: 19/12/2007 19:37
> >>
> >
>
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