Re: a newbie's first post: gum, temperaprint, oil printing, sizing, and computer negatives

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From: Christina Z. Anderson (zphoto@montana.net)
Date: 06/13/03-10:32:50 PM Z


>Judy said: There's also the fact that we don't know what the hell Demachy
was using for gum.
> He probably mixed it himself, it may have been sour, which changes its
> behavior, and .... how thick was it to begin with?

     It was mixed thicker than we do today: 1 gum +2 water, vs. today's 1
gum +3 water, which surprised me, as I said in a previous post. The only
time Demachy recommended the addition of water was when the paper was
presensitized with dichromate alone, and then later coated with a
gum/pigment/no dichromate mixture. To make the mixture spreadable, he
advocated adding water in the same proportion as you would have added
dichromate.
     This is not to say Demachy is the benchmark, or the gum god, by any
means.
>
I have found my most luck with monochrome gums
> > with this method to date.
>
> Would you explain why this is better than one coat if you're using the
> same negative? I've never tried it, but I gather that you are in effect
> doing the "second" coat blind -- that is, without having seen the first
> coat.> Judy

I should clarify. What has worked best for me is not one coat gum or one
color gum, but two or three layers of gum on top of one another that
produces a more monochrome "looking" image--e.g. burnt sienna and black, or
yellow, burnt umber, and blue, for instance--because I haven't yet gotten
the dilutions of each color down correctly to make a tricolor/CMY(K) print
to look normal--it usually is biased to a particular color, you know? You do
see the image printed out so it is not totally a blind proposition, but you
never know what you get until development for the first run thru of that
negative.
Chris


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