Re: Reversal processing for enlarged negatives

----- Original Message -----
From: "Ryuji Suzuki" <rs@silvergrain.org>
To: <alt-photo-process-l@sask.usask.ca>;
<liam.lawless@blueyonder.co.uk>
Sent: Wednesday, March 24, 2004 8:03 PM
Subject: Re: Reversal processing for enlarged negatives

> From: Liam Lawless <liam.lawless@blueyonder.co.uk>
> Subject: Re: Reversal processing for enlarged negatives
> Date: Thu, 25 Mar 2004 03:16:20 +0000
>
> > My guess is that it may be due to your not
> > using a black (or yellow/orange/red) card under the
film - for exposure
> > under the enlarger as well as flashing.
>
> I don't know about your film but my lith films have quite
dense base
> dye until the material is processed. The reflected light
has to go
> through the base twice. Also, silver halide crystals are
quite dense
> to specular light, and this is the reason I suggested to
flash the
> film from both sides to expose large grains, which are to
be bleached
> out.
>
> > I'm slightly confused by Ryuji's suggestion of using
KRST as a
> > redeveloper, if I've understood him right. In toning
experiments many
> > years ago I did try redeveloping bleached prints with
selenium
> > (home-make Kodak T-56, not KRST... or is selenium T-55?)
and I seem to
> > remember that stock strength solution would eventually
yield a soft,
> > brownish image if allowed long enough to do so (a very
long time!), but
> > I can't imagine it being any use in reversal, other than
by toning to
> > strengthen an otherwise finished neg. On the other
hand, it was a very
> > long time ago and I don't remember if I was using some
weird bleach, so
> > maybe I'm wrong... in which case apologies to Ryuji.
Has anyone tried
> > this?
>
> I suggest to try KRST in place of fogging and
redevelopment as a way
> to ensure redevelopment of all silver halide crystals.
Using KRST will
> redevelop more crystals than room light exposure and
ordinary
> redevelopment. This will keep more fine grains and
contribute to Dmax
> as well as reduced granularity. But denser result may have
to be
> compensated for by more initial exposure (imagewise, flash
or both).
>
   Is KRST better than KBT or a solution of Sodium Sulfide?
Sulfide has been used as a reversal "redeveloper" in the
past but results in a sepia image. I am wondering about the
ammonium thiosulfate in KRST or is it not there in
sufficient quantity to fix out enough halide to matter?
  Will KRST result in a more neutral image? I have never
tried KRST as an indirect toner but understand that it can
be used that way, which would be similar to its use for
reversal.

---
Richard Knoppow
Los Angeles, CA, USA
dickburk@ix.netcom.com