U of S | Mailing List Archive | alt-photo-process-l | RE: archivalness of gum

RE: archivalness of gum

	Which is what I asked in my posting three hours ago...has anyone
determined that the ghost image is, indeed, pt/pd metal?  I found the same
ghosting on a BACKING board with silver-gelatin prints.
	Jury still out?

-----Original Message-----
From: Katharine Thayer [mailto:kthayer@pacifier.com] 
Sent: Friday, December 21, 2007 12:09 PM
To: alt-photo-process-l@usask.ca
Subject: Re: archivalness of gum

Well, now that I've read the article, (thanks, John!)  I see that  
(assuming the author is knowledgeable on the subject) no one has  
actually tested to see whether the transfer constitutes a transfer of  
platinum metal to the facing paper or not.  And the fact the  
transferred image can appear on the back side of the print as well as  
on a facing paper also seems to suggest that it's not a transfer of  
metal from the surface of the print that's causing the ghost image.   
So it looks like my analogy isn't apt.

On Dec 20, 2007, at 8:24 PM, Katharine Thayer wrote:

> If you faced a charcoal or graphite drawing with a piece of paper,  
> a small amount of the charcoal would come off onto the facing paper  
> too, but that wouldn't make the charcoal any less archival in and  
> of itself, it just means you want to be sure to frame it so that   
> it doesn't rub off on anything.  I'm not sure I understand why the  
> fact that a small portion of  the metal that comprises a platinum  
> print could rub off on something else detracts from its  
> archivality.   Is it likely to lose enough metal from the surface  
> to actually degrade the image?
> kt
> On Dec 20, 2007, at 7:53 PM, Diana Bloomfield wrote:
>> 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.

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