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

Re: Unknown areas in Gum printing?, etc.

LMAO—Lot's of Mayonaise

sounds like the makings of ...... a BLT TOME!

In a message dated 5/1/07 11:57:38 AM, kthayer@pacifier.com writes:

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 

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 
Katharine Thayer

Best Wishes,
Mark Nelson

Precision Digital Negatives - The System
PDNPrint Forum at Yahoo Groups

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