RE: archivalness of gum
DEAR KATHERINE, 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? HOLIDAY CHEERS! BOB -----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. kt 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. >>>> >>>> >>> >>> >>> >>> >> >> >> > > __________ NOD32 2741 (20071221) Information __________ This message was checked by NOD32 antivirus system. http://www.eset.com
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