From: Christina Z. Anderson (zphoto@montana.net)
Date: 06/16/03-09:46:12 AM Z
> Hi Chris,
> What's the difference, I wonder, between this latter effect described by
> Demachy and the dark reaction, which starts as soon as the paper is
> coated even with the freshest of gum (except apparently in Montana;
> didn't you say that you can keep coated paper there for days or weeks
> without fogging?)
I'm thinking nothing---the ultimate result being hardened gum
everywhere, and even in the highlights, and a reduction in contrast I
assume. OHHH, no, there is something. In dark reaction the dichromates
darken to a brown, whereas with the lemon juice and exposure right away that
wouldn't happen, but that is inconsequential as when the dichromates wash
out, the darkened dichromate is no longer there.
I can't wait to test this dark reaction in SC, where it is totally
humid, compared to MT that is totally dry. I bet there will be differences
in practice (Sam, can you attest to this?) due to the humidity and due to
the lower altitude vs the MT high UV in the mountains at 5000 ft. However, I
wasn't exposing outside.
When I did the Berger method there, I could coat a paper, dry with a
blow dryer til dry to the touch in 2 minutes or less, expose, and then coat
again, dry 2 minutes, expose, and you could whip out a mulitlayered
registered gum print in an hour. I quit worrying about the gum layer being
dry all the way thru after Kosar said moisture increased the speed of the
dichromate. I only worried about it being dry enough to not wreck the neg,
but with diginegs it probably wouldn't be the end of the world to wreck a
neg that costs 40 cents.
With greater humidity this may be a different proposition. Maybe I'll
have to do the Wall methyl alcohol addition--and throw another variable into
the mix. Or Melvin's NEW discovery we are going to learn about at APIS in
one short month from now :) Santa Fe here I come.
Chris
>
> I don't know about the lemon juice, but if it acts as Demachy said, then
> it sounds like both the lemon juice and the dark reaction he describes
> would indeed provide the same outcome: an overall "tone" on the paper
> similar to fogging. If someone wanted for some reason to fog the paper
> lightly, for example when one doesn't want paper-white highlights, the
> simplest way to accomplish that is to expose the paper briefly to light
> without a negative, just as you would "flash" a paper briefly in silver
> printing.
> kt
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