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  1. #1

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    RA-4 developer homebrew critique

    I've been using the following formula as an RA4 developer (found on http://www.bonavolta.ch/hobby/en/pho...hemicals.htm):

    Water (Room Temp) 750.0ml
    Triethanolamine 6.0ml
    Sodium Sulfite, Anh. 1.0g
    CD-3 5.0g
    Potassium Carbonate 40.0g
    Sodium Chloride 0.5g
    Tinopal SFP 0.5g
    Water to make 1.0L

    Except I use a different (Sprint Systems) or no brightener, Tinopal not being available to me.

    I find that while this formula is apparently designed to use at 95 deg F for 1 minute, it seems to work best at 100 deg for 1.5 minutes, leaving me to wonder whether the formula can be improved. Any suggestions? I thought of maybe boosting the CD3 a bit as that has produced results in other areas (eg., small tank processing of ECN-2), but otherwise, I'm at a loss. I like to mix my own chems as it is convenient and extremely economical. Any suggestions/comments on the above formula or alternative homebrew RA4 formulae would be gratefully received.

  2. #2
    Rudeofus's Avatar
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    This formula (correct link here) does not list a pH value which makes its activity more or less a random guess. The author even states that Hydroxide can be added to make it more active, so that's the first thing I would try with this formula ...
    Trying to be the best of whatever I am, even if what I am is no good.

  3. #3

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    Hi I have also found an earlier APUG thread discussing this formula, which suggested the pH was too high and also that by reducing the amount of sulfite, the activity of the developer could be increased. So I am playing around with the formula now and should see soon what any changes in results happen to be.

  4. #4
    RPC
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    I believe I started the thread you are referring to and I have since tried it with Fuji CAII paper as well as Endura and found that by lowering the carbonate to 30 grams no pH adjustment is necessary (keep sulfite at .2 grams) and it works well with both papers, normal contrast with no crossover. In fact, I normally prefer it over the Kodak RA-RT developer, although I still use both. Use at 68 F for two minutes. Mix with distilled water. I don't know how it will perform at high temperatures. Contrast can be controlled by altering the amount of carbonate but watch for crossover. It is odor free but has a life of only days. I mix it as I need it. Also, it has no tar preventing chemicals so expect a little build-up. Most can be removed with alcohol.

  5. #5

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    Hi RPC, well I took your comments from the prior thread on board, and this is what I did: Using Sodium Carbonate instead of Potassium Carbonate (the original formula would have required 31g sod. carb) I reduced the amount to 25g. I increased the CD3 to 5.5g. And I reduced sulfite to 0.2g. Developing for 1 min at 97 degrees, the results with Ektacolor Edge seemed very good indeed. The pH was 10.4 or so, but my meter may read a bit high.

  6. #6
    RPC
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    Glad it is working for you. I have been using this developer when I need normal contrast with the Fuji paper. To me, the Kodak developer is a bit too contrasty for people pictures/skin tones with this paper.

  7. #7

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    Well I would like to be able to increase contrast to print with ECN-2 negatives. It seems to me that reducing the carbonate has increased contrast a bit, or should that be the other way around? Maybe it was the slight increase in CD3. I may go to 6g/L CD3 and see what happens.

    I can increase contrast a lot by adding H2o2 but want to perfect the basic formula first.

  8. #8
    RPC
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    The contrast should increase if you increase the carbonate. The increase you experienced might be to do with using sodium carbonate and/or the paper you are using. To increase more, try adding 5 or 10 grams of the carbonate. That should do it but if you observe unacceptable crossover then give H202 a try.

  9. #9

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    Would the contrast have been increased by reducing the sulfite from 1g/L to 0.2g/L?

  10. #10
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    The pH is critical and should be about 10.5. The additional secret is the use of Lithium salts and and a Sulfonic acid. These changes were needed to offset the removal of Benzyl Alcohol and improve development rate.

    So, IMHO, none of the internet formulas are correct so far. If I can find one, I'll post it here someday.

    PE

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