JD-2 chemistry (bleach)
On: Tue, Dec 18, 01 07:06:55 PM
John Wagner wrote:
|Hi everyone. I have a quick question about the JD-2 bleach.
I am using bb-640 plates and developing them with the Kodak
D19 developer. ( I am a complete beginner ) My plates are
very dark, I think I'm not using the correct bleach. I
purchased the bleach as part of a two part system ( tonner
and bleach ) as that was all I could find available. I
have decided to make up my own bleach. The JD-2 system uses
Potassium Dichromate and Sodium Bisulfate. Could someone
tell me how much ( in grams ) I need of these two compounds
to make up a litre of the JD-2 bleach?
Also... my very limited understanding of film developing is
that there is a developer stage and a fixing stage,
separatly, ( this is what I am doing with the Kodak
chemicals ). The JD-2 system does not seem to have a fixing
stage, just the two part developer. When mixed, do the two
parts of this developer act as the developer AND the fixer
in the same solution? I am a little confused about this
If anyone could advise on the above I would be grateful.
Tom B. - Wed, Dec 19, 01 04:22:30 AM The Photographer's Formulary JD-2 bleach uses 5 grams
Potassium Dichomate + 80 grams Sodium Bisulfate +
distilled water to make 1 liter. This corresponds to
Jeff Blyth's pyrochrome recipe.
Most holographic processes don't use a fixing step. This
is done mainly for amplitude holograms. One problem
with fixing is that removing the unexposed silver
salts shrinks the emulsion 15-20%, which is usually
Info from Bjelkhagen's "Silver-Halide Recording Materials
John Wagner - Wed, Dec 19, 01 07:30:00 AM Thanks Tom.
If that is the case then, should I skip the fixing step,
(using the Kodak D19 developer) and go straight to the
bleach stage or will I still have to fix the plates if not
using JD-2 chemistry? 126.96.36.199
Tom B. - Wed, Dec 19, 01 11:59:18 AM I think skipping the fix step is the best bet. You
will likely want to rinse for 2 to 5 minutes in
running tap water before bleaching. And also after bleaching.
Colin Kaminski - Mon, Dec 24, 01 08:13:01 AM I guess it should be mentioned that fixing also incrases
grain size and decreases resolution. If you must fix use
the least agressive fixer you can find.
If you are looking to desensitise the film Bjelkhagen
Phenosafranine (C18H15CIN4) 300 mg
Methonal .5 L
Distilled Water .5 L
Use for 3 minutes.
If you must fix:
Fix in Kodak F-24
Expect a 20% to 50% decrease in image resolution. This is
taken directly from Silver-Halide Recording Materials. 188.8.131.52
Spam - Wed, Feb 27, 02 10:47:40 AM THis DOsEnT MaKe AnY sence??????????
Natalie - Sun, Dec 01, 02 02:11:54 PM I disagree with skipping the fixing stage completly!
Although it may make the grain size it will decrease the
resolution of the photo's, the fixer is inteded to blend
the chemicals(especially developer and the stop bath)
together, if you skip this stage then the photo's will not
be nearly as clear and the contrast will be harder to
deepen in the printing stage. If the photos were taken well
and high quality film was used then there shoulof be no
need to skip the fixing stage. 184.108.40.206
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