From: troyb@oz.plymouth.edu (Troy Bennet)
Subject: Re: Dye Chrome Chemistry
Reply-To: troyb@oz.plymouth.edu (Troy Bennet)
Organization: Plymouth State College - Plymouth, N.H.
Date: Thu, 20 Aug 92 14:54:15 GMT

In article <16848D4CE.MSPERKO@kentvm.kent.edu> MSPERKO@kentvm.kent.edu (Mike Sperko) writes:
>Does anybody on rec.photo have any experience with either E-6 or K-1 Cibachrome
>processing chemistry from Dye Chrome Research Co..  These processing kits are
>powder that need to be mixed.  The K-1 Ciba kit is supposed to be variable cont
>rast chemistry.  I would appreciate hearing from anybody that has used this any
>of these products.
>
>Thanks,
>Mike Sperko
>

The Dye Chrome company in Florida actually makes two powder chem kits
for processing Ilfochrome (cibas).  The only difference between the
original K-1 kit and the newer K-2 kit is that the K-2 kit is
redesigned to work within a different temperatur range than the 1st
kit. It might have a better tolerance for temp variations too.  I
first heard about this chemistry several years ago.  I decided to try
it out specifically for the contrast control.  What they have done is
to divide the bleaching step into two steps, silver bleach and dye
bleach.  By varying the amount of time in the first bleach step (I
forget which was first, silver or dye) you can control the amount
contrast in the print.

All of this great contrast control does not come without problems
though.  First off, the amount of time that you process in the first
bleach step does indeed control the level of contrast in the print.
However, at the same time, it also alters the emulsion speed of the
paper.  Not only that, it alters the color balance of the print.  If
this isn't enough, in order to really get critically consistent print
exposure and color balance, you have to stay within the chemistry's
temp tolerance of 0.1 deg F.  Time is critical too.  10 sec either way
will have some effect.

Now all of this sounds rather discouraging I'm sure.  To be fair
though, It is possible for someone with just a basic Ciba drum and
enough counter space to roll it back and forth, to get decent cibas
with this kit (K-1).   The first thing that I would recommend is to
first attack the temp problem.  I used a large dish pan filled with
water at the exact temp as a pretemping box for all of my chemistry.
My thermometer is an Ilford Cibachrome Dial thermometer that isn't as
accurate as needed here, but I used it with care, seeing to it that
the temp was as dead-on as possible. I also used a space heater to try
and keep the ambient room temp as close to the processing temp as
possible.  Thisrequired me to do some testing with the heat settings
and amount of time needed to bring not only the air but the counter
tops up to temp.  A humidifyer works very well for both keeping dust
problems down and for stabilizing room temp.  The next step is to make
a print using the standard bleaching times given in the instructions.
 The trick is to first determine what level of contrast control you
need for a particular slide.  The next step is to make another print
using the bleaching time that will give you the amount of contrast
control you need.  The next step is to make a test strip to determine
the correct exposure.  Make a print at your determined correct
exposure.  By this time, you should have a print that is properly
exposed and with the desired amount of contrast.  The last step/steps
are to make prints that are properly filtered to give you the desired
color balance.  This gets tricky because changing the filter pack will
affect the exposure.  At this stage you have to get the color right
and tweak the exposure afterward.

As you can see, there is a lot of paper used up just to get to the
point where you can get consistent prints from a single slide.  It
didn't take long before I just decided that I was only after a couple
of prints per slide and that the level of consistency that the Dye
Chrome people were concerned with was beyond my personal needs.  I
loosened up the whole procedure to fit my style and I got decent
results.

I eventually went back to using the Ilford chemistry because it was
simpler to mix-up, easier and faster to use, and had some provision
for deactivating itself for somewhat safer disposal.  Between the low
contrast paper and the standard stuff I have all of the contrast
control I need.  Besides, the Dye Chrome kits are not intended for
salvaging way out exposures, you'd still need some masking to remedy
that.

BTW, I did manage to get a pretty decent level of contrast control
using Rodinal for developer, Ciba bleach, and Sprint Fixer.  I used
this processing method on the ciba AII paper that was out just before
Ilford changed over to the Ilfochrome name.


troyb
Newsgroups: rec.photo