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  1. #11
    Ian Grant's Avatar
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    Quote Originally Posted by dr5chrome View Post
    Pe; back when R printing was around I was considering modifying the process to accept B&W RC paper [light reversal]. do you think a modification of the R process would be a better reversal B&W printing solution?
    dw
    If you look at the Pathescope (1947) first developer you'll see this is actually a simple colour developer. Also some of the early additive colour processes used similar developers even though there's no dye coupling taking place.

    As I said in a previous thread sometimes when you look back it gives you clues to other avenues for going forward

    Ian
    Last edited by Ian Grant; 12-13-2008 at 12:20 AM. Click to view previous post history. Reason: add

  2. #12
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    One thing not mentioned is the sulfite bath, CB1. This is what keeps the negative image from redeveloping as well as having the proper bleach, which it appears you do. Maybe a longer time in CB1 would help or a higher concentration?
    Gary Beasley

  3. #13
    Ian Grant's Avatar
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    Quote Originally Posted by glbeas View Post
    One thing not mentioned is the sulfite bath, CB1. This is what keeps the negative image from redeveloping as well as having the proper bleach, which it appears you do. Maybe a longer time in CB1 would help or a higher concentration?
    No, that's wrong the negative image has already gone the bleach has dissolved the exposed & processed Silver which was converted back to Silver. The sulphite removes the staining caused by the bleach bath if a dichromate bleach is used, metabisulpite does the same if a permanganate bleach is used.

    The sulphite/metabisulphite will also act a bit like HCA to help remove the last traces of the bleached silver from the emulsion.

    Yes it's a vital step but if you left it out you'd still get an image, although possibly very slightly degraded.

    Ian
    Last edited by Ian Grant; 12-13-2008 at 01:17 PM. Click to view previous post history. Reason: change part to Silver

  4. #14
    Ian Grant's Avatar
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    This might be an option Keith and David EFke Direct Positive paper from Freestyle.

    Just found the notebook I started in the mid 70's, and there's a scribbled line at the end of the two B&W reversal Formulae I'd tried. "B&W paper can be reversal processed with any normal print developer as the first developer". I guess the word normal means clean working & not warm toned. Also says G-14, not sure what that is. I've seen an a piece in a book about making B&W prints from colour transparencies and I'm sure that was similar, develop as normal then rinse well, and go through the other stages of the reversal process. I What ever the book is it's in storage in the UK at the moment. 'm sure Kodak made suggestions for how to produce B&W prints from slides as well, these would be equally applicable to a B&W transparency.

    Ian

  5. #15
    Photo Engineer's Avatar
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    Regarding the Pathescope and R processes, p-phenylene diamine itself is a very poor color developer but a good, albeit weak, low contrast B&W developer. It was in common use about 100 years ago or thereabouts. The R process used a rehal bleach and would therefore be unsuitable for reversal B&W and changing it would render it so totally different it would be a different process entirely.

    As for the clearing bath, it is used to reduce all of the excess dichromate left in the film (or permanganate for that matter depending on which bleach you use) and prevent carryover into the second developer. If you do that, the alkali mixed with the oxidant/reductant causes severe image problems.

    All B&W and color processes with dichromate, permanganate, ferricyanide and other strong bleaches, whether B&W or color, require a clearing bath after the bleach and often before the bleach as well to remove oxidants and reductants and prevent stain formation or unwanted image problems.

    PE

  6. #16
    Ian Grant's Avatar
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    Quote Originally Posted by Photo Engineer View Post
    Regarding the Pathescope and R processes, p-phenylene diamine itself is a very poor color developer but a good, albeit weak, low contrast B&W developer. It was in common use about 100 years ago or thereabouts.
    PE
    It was still common until the 1980's and beyond, but only in B&W developers, it's in some Edwal Developers, and of course both Sease and Crawley used it as well. Some current commercial B&W developers use a derivative.

    Ian

  7. #17
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    PE;
    my reference was to 'R' "procedure" it self, naming the use of an R-processor.

    Of coarse the color chemistry would not function with B&W material, I am familiar with the R-color process.

    I have access to an old R machine. Idea's on where to start for bath replacement for B&W paper? I am not so sure dichromate is the best route for paper. [sorry, not interested in grants opinion, his post are blocked any way, but he is welcome to reply to others ]

    dw


    Quote Originally Posted by Photo Engineer View Post
    Regarding the Pathescope and R processes, p-phenylene diamine itself is a very poor color developer but a good, albeit weak, low contrast B&W developer. It was in common use about 100 years ago or thereabouts. The R process used a rehal bleach and would therefore be unsuitable for reversal B&W and changing it would render it so totally different it would be a different process entirely.

    As for the clearing bath, it is used to reduce all of the excess dichromate left in the film (or permanganate for that matter depending on which bleach you use) and prevent carryover into the second developer. If you do that, the alkali mixed with the oxidant/reductant causes severe image problems.

    All B&W and color processes with dichromate, permanganate, ferricyanide and other strong bleaches, whether B&W or color, require a clearing bath after the bleach and often before the bleach as well to remove oxidants and reductants and prevent stain formation or unwanted image problems.

    PE
    Last edited by dr5chrome; 12-13-2008 at 04:32 PM. Click to view previous post history.

  8. #18
    Ian Grant's Avatar
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    Quote Originally Posted by dr5chrome View Post
    PE;
    my reference was to 'R' "procedure" it self, naming the use of an R-processor.

    Of coarse the color chemistry would not function with B&W material, I am familiar with the R-color process.

    I have access to an old R machine. Idea's on where to start for bath replacement for B&W paper? I am not so sure dichromate is the best route for paper.

    dw
    Your the expert on Reversal processing so why ask such simple questions.

    Plenty of people haver used Bichromate bleaches for B&W papers and published their experiences.

    Ian

  9. #19
    Ian Grant's Avatar
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    Quote Originally Posted by dr5chrome View Post
    PE;
    my reference was to 'R' "procedure" it self, naming the use of an R-processor.

    Of coarse the color chemistry would not function with B&W material, I am familiar with the R-color process.

    I have access to an old R machine. Idea's on where to start for bath replacement for B&W paper? I am not so sure dichromate is the best route for paper. [sorry, not interested in grants opinion, his post are blocked any way, but he is welcome to reply to others ]

    dw
    It's sad that your negative attitude means people turn away from your DR5 process, and your company full stop.

    You have a good service but you are also your own worst enemy. I have NEVER seen anyone complain about your processing but only about your attitude.

    You have competition you'll soon have more, but don't over hype your services.

    Ian

  10. #20
    Photo Engineer's Avatar
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    Quote Originally Posted by dr5chrome View Post
    PE;
    my reference was to 'R' "procedure" it self, naming the use of an R-processor.

    Of coarse the color chemistry would not function with B&W material, I am familiar with the R-color process.

    I have access to an old R machine. Idea's on where to start for bath replacement for B&W paper? I am not so sure dichromate is the best route for paper. [sorry, not interested in grants opinion, his post are blocked any way, but he is welcome to reply to others ]

    dw
    Well, then, it has become obvious to you that I know nothing about the "R" processor only the color "R" process itself and got them confuse having no information on hte former.

    PE

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