From: Rod Fleming (rodfleming@sol.co.uk)
Date: 08/31/00-12:49:29 PM Z
Hi
Quite right. Farmer's is a "cutting" reducer- it removes density equally
from the highlight and shadow areas. This is not what we want here! The
SLIMT method is very effective but like all these things it has to be done
the right way. David Kachel gives a very thorough and easily understandable
description of the method on the link I posted last night. I really think
anyone thinking of experimenting with this versatile and useful technique
needs to study carefully the papers Kachel has written on it.
In very broad terms using SLIMT in the printing process allow you to
compress the overall tonal range while at the same time maintaining good
separation of nearly adjacent tones. Not all images need it, but it is a
wonder with some negs. I use it quite often. On some landscape pictures the
same effect could only be got with hours of work making masks, and
considerable manipulation of the exposure too. One of the joys of SLIMT for
printing is you can try a certain combination of exposure vs bleach, and if
you don't like the effect you can modify it right away by trying again with
a slightly different combination. Masks would take a little longer. (Which
is not to say that masks are redundant, just that this is a great addition
to the toolkit.)
In film processing it allows very precise control over zonal contraction
without getting "flat" negs. I am not going to dare to try to explain a
method which I am still discovering myself (the method for zonal contraction
of film is _much_ more complicated than contrast control for prints).
However SLIMT allows really precise control of the curve to an extent which
I had hitherto thought only possible with a computer! However you really
must read the papers before you plunge in. This is a very powerful but
involved procedure.
Note that if you're using the bleach (pot ferri) with film you need to add
Potassium Bromide to prevent fogging. This is not required for paper. (But
_no_ hypo!)
Finally everyone really should have pot ferri in the cupboard, along with
hypo. Although Farmer's, which is just those two mixed, can't be used for
SLIMT, used on a watercolour brush and applied directly to the devved and
fixed print it allows yet another method of manipulation and control, which
is subtle and can be very precisely applied.
Rod
----- Original Message -----
From: "Sil Horwitz" <silh@earthlink.net>
To: <alt-photo-process-l@skyway.usask.ca>
Sent: Thursday, August 31, 2000 5:07 PM
Subject: RE: PRE DEVELOPMENT BLEACHING
> At 2000/08/31 08:47 AM -0400, Joachim wrote:
> >I had also tried contrast reduction for litho with Farmer's diluted and
> >found results so erratic that I abandoned it.
>
> Farmer's is ferricyanide plus hypo - won't work properly. The plain
> ferricyanide is a weak bleach only, while Farmer's will actually etch out
> some of the image (in the highlights of a print, unfortunately not what
you
> want it to do). When you use the dilute ferricyanide, it changes the
> molecular structure of the undeveloped silver. I don't know the exact
> structure, but it is definitely not a bleach like Farmer's, which is a
> combination with hypo.
>
>
> Sil Horwitz, FPSA
> Technical Editor, PSA Journal
> teched@psa-photo.org
> silh@earthlink.net
> Visit http://www.psa-photo.org/
> Personal page: http://home.earthlink.net/~silh/
>
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