Re: pyrogallol & pyrocatechin

On Sat, 3 Apr 2004, Ryuji Suzuki wrote:

> From: "Gordon J. Holtslander" <holtsg@duke.usask.ca>
> Subject: pyrogallol & pyrocatechin
> Date: Fri, 02 Apr 2004 21:15:40 -0600
>
> > I use a low pH phenidone ascorbic acid developer to produce continuous
> > tone negatives from ortho lith film. It works well, but suffers from slow
> > speed and poor shadow detail - its essential to pre-flash to get any
> > shadow detail.
>
> I've found that problem with some films, particularly Freestyle APH
> film. Kodalith Ortho 6556 Type 3 or Ektagraphic HC gives better speed
> and also higher Dmax at low gamma. I think APH type films need to be
> processed in more vigorous developer (such as D-19 or D-72/Dektol) and
> accept high contrast.

I use Kodak Polychrome Graphics Camera 2000 CGP film. I don't know how it
would compare to the above films. Getting Freestyle APH in Canada is
prohibitively expensive. I've never tried it.

>
> If you or anyone is interested in history of developing agents and
> their evolutions in practical formula, from practical aspects put in
> parallel to studies on mechanisms of development, Levenson has
> published a couple of excellent review articles from 60's to late 80's
> and I can get you the reference info next week. Henn has written some
> good ones as well, but these are more chemistry oriented. (No, none
> of them is in PDF files.)

I would love these references :)

> --
> Ryuji Suzuki
> "All the truth in the world adds up to one big lie." (Bob Dylan 2000)
>

Gord

---------------------------------------------------------
Gordon J. Holtslander Dept. of Biology
holtsg@duke.usask.ca 112 Science Place
http://duke.usask.ca/~holtsg University of Saskatchewan
Tel (306) 966-4433 Saskatoon, Saskatchewan
Fax (306) 966-4461 Canada S7N 5E2
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Received on Sat Apr 3 11:00:54 2004