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 point :-) If anyone could advise on the above I would be grateful. John Wagner

RESPONSES

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 undesirable. Info from Bjelkhagen's "Silver-Halide Recording Materials for Holography" 24.67.253.203

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? 203.96.111.201

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. 24.67.253.203

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 recomends: Phenosafranine (C18H15CIN4) 300 mg Methonal .5 L Distilled Water .5 L Use for 3 minutes. If you must fix: Develop Wash Fix in Kodak F-24 Wash Hypoclear Bleach Expect a 20% to 50% decrease in image resolution. This is taken directly from Silver-Halide Recording Materials. 64.170.192.223

Spam - Wed, Feb 27, 02 10:47:40 AM

THis DOsEnT MaKe AnY sence?????????? 205.213.111.50

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. 66.185.85.78


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