RE: Gum hardening: top down experiment

Thanks for this, Yves, a very thorough explanation of the physics of
exposure, which I, not having any knowledge of physics at all, was not aware
of.

Kate M

-----Original Message-----
From: Yves Gauvreau [mailto:gauvreau-yves@sympatico.ca]
Sent: Thursday, 13 April 2006 11:49 p.m.
To: alt-photo-process-l@usask.ca
Subject: Re: Gum hardening: top down experiment

Hi all,

I think in all this discussion about the top down hardening or vice-versa
many of you forget one, if not the most important, point. Unless physical
laws have change recently behind my back, Ok not behind my back I just
haven't look at it lately but anyway before anything happen with the
chemical stuff, be it the gum, the pigment, the dichro and even the paper,
the photons (light) must reach these molecules which ever they are and the
laws of physics say that if a photo hits an atom in one of those molecules
it will be absorb, the mechanism of which is irrelevant at this time.
However thin you can make a gum emultion on a piece of paper or whatever,
this emultion will deposit on the substrate an extremely large number of
molecules and as all of you know already these molecules are made of atoms.

Etc....

----- Original Message -----
From: "Sandy King" <sanking@clemson.edu>
To: <alt-photo-process-l@usask.ca>
Sent: Wednesday, April 12, 2006 11:21 PM
Subject: RE: Gum hardening: top down experiment

> >
> >Which is to say, I would say a print on plastic is a different
> >medium, an OHP-o-Graph, perhaps. If it proves to be hardened from
> >top or bottom, very interesting, but I print on paper, and much of
> >what I've read (including the sainted, notorious, blessed/evil Mike
> >Ware) AND my own experience shows the paper to be an active part of
> >the process.
> >
> >The dichromate (with or without gum) DOES sink into the fibers of the
> >paper. But does it just lie there like a lotke (it's Passover, folks,
> >if I could spell lotke confidently I'd tell you more), or is it part
> >of the action? My impression is that it's active, and I point out
> >that IME each paper performs differently. I suspect more than just
> >sizes are different, but the fact that different papers need
> >different sizes is also a clue.
> >
> >J.
>
>
> I don't disagree with any of this. A print made on plastic exposing
> through the surface of the plastic would have IMHO different image
> characteristics. In fact, I have stated that opinion several times.
>
> As for gum on paper, I have no opinion, other than until someone
> presents a compelling theory as to why image formation is not
> primarily top down I will continue to believe that it is. Hopefully
> Chris will address that in her class this summer in SF.
>
> Sandy
>
>

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