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  1. #11
    titrisol's Avatar
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    Yes, that is what we discussed as Kodalk replacement.

    Quote Originally Posted by psvensson
    That approximates metaborate, right? I've tried metaborate as the alkali too, but it didn't give a full D-max.
    Re: D-max problem I think you may need to increase the phenidone:ascorbate ratio
    it is definitely a lack of activity
    Mama took my APX away.....

  2. #12
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    Quote Originally Posted by Mark Layne
    I would like to try adding Sodium Ascorbate to Rodinal.
    Does this masquerade in the supermarket under some common name or does it have to come from a chemical supplier?
    Mark
    Most of the ascorbates I have seen in health food stores are calcium, which is not of much use in developers because it causes much precipitation. The best way is to use ascorbic acid with baking soda in the ratio of 2 tsp ascorbic acid to 1 tsp of baking soda. This is close enough neutral for government work. Mix it in an ounce or so of water and let the effervescence subside before adding it to the developer solution.
    Gadget Gainer

  3. #13
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    Quote Originally Posted by titrisol
    Yes, that is what we discussed as Kodalk replacement.



    Re: D-max problem I think you may need to increase the phenidone:ascorbate ratio
    it is definitely a lack of activity
    The activity of an ascorbate-phenidone mixture goes UP rapidly from 10:1 to 20:1 and less rapidly from 20:1 to 40:1 as you hold phenidone constant. From 40:1, it continues to increase gradually in activity. The assumption is that you keep pH constant, which will happen if you use sodium ascorbate made as in the previous post. If you take it to the extreme of 0 ascorbate, you will understand the reason why that is true. Phenidone alone is not a contrasty developer, and is not particularly well preserved by sulfite.

    In answer to another question, the pink color is a sign of oxidation of the phenidone. Ascorbate is more of an orange. Increasing the phenidone will not help as much as increasing the ratio of ascorbate to phenidone while making sure that alkalinity is constant. That means if you use ascorbic acid, increase whatever alkali you are using as you increase the ascorbic acid.

    The things you do by habit with MQ or PQ developers are not always profitable in MC or PC. The chemistry of the reactions is different. The product of reduction of silver bromide by ascorbate is dehydroascorbate and HBr with the result that local pH and eventually overall pH rises.
    Gadget Gainer

  4. #14
    gainer's Avatar
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    I forgot to mention that the ratio of lye to borax that I mantioned gives a higher pH than Kodalk.
    Gadget Gainer

  5. #15

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    Quote Originally Posted by dancqu
    Have you tested at constant ph?
    No, I don't have a pH meter. Maybe someone knows approximately how pH will vary with sulfite concentration in a D-76-type developer?

  6. #16

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    Quote Originally Posted by gainer
    Most of the ascorbates I have seen in health food stores are calcium, which is not of much use in developers because it causes much precipitation. The best way is to use ascorbic acid with baking soda in the ratio of 2 tsp ascorbic acid to 1 tsp of baking soda. This is close enough neutral for government work. Mix it in an ounce or so of water and let the effervescence subside before adding it to the developer solution.
    Thanks very much for this tip Pat

    Mark
    Mark Layne
    Nova Scotia
    and Barbados

  7. #17

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    Quote Originally Posted by psvensson
    In my experience with E-76-type developers,
    sulfite concentration has a very strong effect on activity.
    It has no effect then it does have an effect. If you varied the
    amount of sulfite very much it would affect the ph. E-76 has,
    IIRC, 8 grams of ascorbic acid.

    The amount could be I'd think as little as 20 grams and have little
    effect. The activity might even increase with some reduction. That
    due at least in part to the solutions lower ionic strength.

    You've not given any details. Is E-76 more or less active with more
    or less sulfite. Your findings contradict Haist's according to another
    post. Haist is considered quite an authority.

  8. #18

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    Quote Originally Posted by dancqu
    You've not given any details. Is E-76 more or less active with more
    or less sulfite. Your findings contradict Haist's according to another
    post. Haist is considered quite an authority.
    More sulfite makes the developer more active. As quoted by Tom, Haist's statement does not make any sense, or at least, is much too far-reaching. My favorite film developer right now is a phenidone-ascorbic formula with sulfite as the only accelerator. Obviously, more sulfite makes it more active.

    Maybe Haist is talking about the fact that sulfite isn't necessary to activate phenidone-ascorbic superadditivity? I don't have the book, so I don't know.

  9. #19

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    Ok, I found some tests I've done that illustrate the effect of sulfite. This is a case where sulfite is not the only accelerant - in fact, the developer works fine without it.

    I exposed a roll of Delta 400 35mm and cut it in three. Each strip was developed in:

    1l water
    0.5 tsp ascorbic acid
    4 ml phenidone/alcohol solution a la Gainer
    20 ml TEA
    9 minutes at 76 F

    Plus added sulfite as follows:
    Strip 1: No sulfite. Contrast 1.14
    Strip 2: 0.5 tsp sulfite. Contrast 1.29
    Strip 3: 2 tsp sulfite. Contrast 1.38

    To me that looks like sulfite has an effect on activity that doesn't spring from its effect on pH, but it's short of conclusive proof.

  10. #20
    gainer's Avatar
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    ANYTHING you add to a developer can have some effect. What I have read is that ascorbate develpers with litle or no sulfite are surface developers, meaning surface of the halide crystal. Surface developers have certain advantages in speed-grain ratio, if you can imagine such a number. When I say that sulfite has no beneficial effect in an ascorbate developer, I refer mostly to the preservative effect, but also I have not seen any beneficial influence on granularity or film speed that you could not obtain without the sulfite. Of course, I haven't seen everything yet. If I make it to Heaven, I'll try to get a message through.
    Gadget Gainer

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