From: Christina Z. Anderson (zphoto@montana.net)
Date: 02/02/03-02:39:01 PM Z
>
> But the drill is to make *soft* positive so you can get through all parts
> of it easily for the negative. (See FotoDave, P-F #2.) If the positive is
> "punchy" it's much harder to get a full scale negative, especially
> separation in shadows & highlights -- or so goes the conventional wisdom.
>
> However, your sharing these tidbits is most extremely pleasurable (so much
> better you than I for the 88 hours in the darkroom). I trust you will tell
> which was easier for the negative, the "dull" Bergger & Plus X or the
> "punchy" tri X. (Perhaps another shibboleth will bite the dust.)
> Meanwhile, how do you gauge the final negs -- got densitometer???
>
Yes, I do have a densitometer at school. It seems with the processes
that you need a final negative with a DR range of 1.4 to even 2.6 I've read,
for a lot of the alt processes. I am not well versed in this all, but it
seems to me that platinum uses the highest DR of all the processes?? Or
maybe salt. Anyway, so the trick would be to get some of the contrast out
of the interpositive, and then the rest out of the final negative. I'm just
going off one writer who said that the interpositive should be .85-.95. So
I look for a neg that has good detail in the highlights and shadows and a DR
that comes close to this. Hope I didn't do it wrong!
I would gauge the final negatives with a densitometer, also--I have one
at work-- but mostly how they print. I have some negs from years ago on
direct dupe film that are about as high contrast as you can go, it seems. I
use one of them for a test neg whenever I start a process to test different
variables. In fact, I tested adding a drop of 40% citric acid to cyanotype
sensitizer (Ware's) to increase levels of tone and it really works! So did
giving a straight white vinegar first bath. Both were able to print in
these bullet proof contrast negs. It is so fun to be able to vary the
contrast of cyano--like a VC paper...
Chris
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