U of S | Mailing List Archive | alt-photo-process-l | Re: Unknown areas in Gum printing?, etc.

Re: Unknown areas in Gum printing?, etc.

I hate to disturb all of you folks falling on the floor laughing and whatever other kinds of hilarity the rest of the acronyms stand for, but you're all laughing at the wrong thing, seems to me.

I have to wonder if any of you who are laughing so hard actually looked at Jacek's step tablets. At any rate, as has often been pointed out in the past, there are people other than Terry King who have used unhardened gelatin for a size and found it worked quite well; I used unhardened gelatin as a size early in my gum printing career, with no problems . But I've come to believe that in cases where unhardened gelatin works well as a size, the same paper will probably work well unsized, at least that's been my experience. So in Jacek's predicament, of not being able to get hardeners, I'd suggest trying the Fabriano paper that worked well with unhardened gelatin, without bothering to size. (I can't remember if he tried that with the Fabriano paper, or only with the Arches).

At any rate, if you want something to fall off your chair laughing over, the idea that if you print gum on unhardened gelatin, the dichromate will harden the entire layer of gelatin, is the laughable idea here, not the idea that unhardened gelatin can serve as a reasonable size. If you print gum on unhardened gelatin, of course the dichromate doesn't harden the gelatin overall, any more than the dichromate hardens the gum coating overall. The hardening occurs differentially as a function of exposure, in both the gum coating and the underlying gelatin layer. This is the fundamental underlying principle of gum printing, and carbon printing too; neither of them could occur without this principle holding true. So this statement that the dichromate would harden the whole layer of gelatin isn't consistent with an accurate understanding of how dichromated colloids work.

I've had on my website for several years a demonstration of what actually happens when gum is printed on unhardened gelatin: as could be predicted from a knowledge of the process, the dichromate in the gum emulsion hardens the underlying gelatin exactly where exposure occurs. Where exposure doesn't occur, the unhardened gelatin stays unhardened and can be washed off with hot water, if a person is concerned about the archival properties of unhardened gelatin, without disturbing the hardened gum or the hardened gelatin under the hardened gum. It may not be the most efficient way to size, but there's nothing particularly wrong or stupid about it either. Here's the page:


I personally would prefer a more reasoned and professional discussion of issues; this hooting and jeering and LMAO and LOLOL and other juvenile expressions of disrespect to colleagues is very annoying on a professional forum and doesn't speak well of our community, besides it shuts down a reasonable discussion of issues. Jacek, when he couldn't find hardeners available, tried printing without a hardener, and the thing is, it's not that unreasonable an idea, as I and others have demonstrated. It certainly didn't deserve all this ridicule.
Katharine Thayer

On May 1, 2007, at 8:16 AM, john@johnbrewerphotography.com wrote:


----- Original Message ----- From: "Christina Z. Anderson" <zphoto@montana.net>
To: <alt-photo-process-l@usask.ca>
Sent: Tuesday, May 01, 2007 3:55 PM
Subject: Re: Unknown areas in Gum printing?, etc.

LOLOL yeah, you ain't a kiddin', don't you remember when I took up Terry King's suggestion to use unhardened gelatin for a size and got wonderful black squares of no image because, OF COURSE, the am di in the gum/pigment mix LOVED the unhardened gelatin and hardened that into a nice complete layer, too. So much for 250 bloom gelatin and all that.
----- Original Message ----- From: "Loris Medici" <mail@loris.medici.name>
To: <alt-photo-process-l@usask.ca>
Sent: Tuesday, May 01, 2007 8:48 AM
Subject: RE: Unknown areas in Gum printing?, etc.

Oops! Sorry for mis-quoting, it was Marek then...

Anyway, that could be better than trying to print on unhardened sizing
(+ w/o struggling to buy a locally restricted chemical) - at least,
that's how I take it ;)


-----Original Message-----
From: Christina Z. Anderson [mailto:zphoto@montana.net]
Sent: Tuesday, May 01, 2007 5:37 PM
To: Alt, List
Subject: Re: Unknown areas in Gum printing?, etc.

Just for the record, Loris, wasn't it Marek or Terry King (not me) who
recommended a hardened layer of di/gum?

If the highlights are protected, there will be slight tone in them with
the di/gum layer, which adds an overall dullness to the image.

But what do I know, I'm one of those glutaraldehyde addicts, you know...

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