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  1. #61
    Rudeofus's Avatar
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    Quote Originally Posted by albada View Post
    The curves, grain and sharpness are all essentially identical to my eye.
    Very nice!
    Quote Originally Posted by albada View Post
    Ryuji said that APX-100 and Pan-F worked poorly in DS-10. Pan-F is still in production, so I'll order some rolls and try it. Thanks for posting that idea. BTW, I thought Ryuji speculated that the failures were caused by DS-10's low pH of 8.0. I'm running at 8.3, which is a tad above XTOL and the same as D-76, so at least the concentrate won't have problems due to low pH.
    Let's not forget: DS-10 also contains a mild silver solvent, TEA. I read somewhere that this, together with long dev times, is the main culprit, why DS-10 doesn't do well with ultra fine grained film stock.
    Quote Originally Posted by albada View Post
    What problems do dissolved minerals in water cause? A search of apug.org shows some calcium specks on negatives if it precipitated out of solution. Also, folks say that carbonate causes calcium to precipitate, which my concentrate lacks, so hopefully that won't be a problem. My tap water is hard, so I'll try it on test-strips tomorrow.
    I'd be afraid of calcium precipitation in any alkaline environment, carbonate or not. There must be a reason why so many recipes contain Calgon and/or EDTA.

    PS: If EDTA and Calgon don't want to dissolve in PG under any circumstances, you could always add them to your sulfite component.
    Trying to be the best of whatever I am, even if what I am is no good.

  2. #62
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    The results look very nice Mark. I'm impressed.

    BTW, that must have been a windy day! Try looking at the images rapidly and you will see what I mean.

    PE

  3. #63

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    So, could you reprint the formula with the order of mixing?

    Thanks

  4. #64

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    Stress-test with 1+1 dilution

    I wanted to test the capacity of this concentrate compared to XTOL. Kodak recommends at least 100 ml of XTOL be used per roll. So I used 100 ml, with 1+1 dilution (200 ml total), for 9 min at 20C (per the MDC). And same with the concentrate. Density-graph and scan-crops are below for Tri-X. The graph is interesting: It shows that under this capacity-stressing condition, the concentrate performed a hair better than XTOL, in that the densities of midtones and highlights are slightly higher. But so slight that folks would probably not notice the difference. Grain and sharpness look the same to me.

    Click image for larger version. 

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    Consistent with the graph, the leaders were 2.03 for XTOL, and 2.07 for the concentrate.

    Frame 20: Xtol: Click image for larger version. 

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    Frame 21: Xtol: Click image for larger version. 

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    Frame 22: Xtol: Click image for larger version. 

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    This test also provides a second comparison of emulsions with conventional grains (ie, not T-grain).

    A question for PE: The low densities in the graph and leaders imply underdevelopment, yet the short toe implies normal development. Can you explain this paradox?

    Mark Overton

  5. #65

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    My replies to postings:

    @Rudeofus: It has recently (2010) been discovered that metaborate sequesters cations such as Ca++. Search for "metaborate sequester". Here's a sentence from what appears to be the first report about this: "A form of borax known as metaborate has been found to sequester divalent cations such as Ca++ and prevent precipitation." The concentrate has a moderate amount of metaborate in it, so perhaps it can keep the calcium in check. How do I test sequestering of calcium and magnesium? I hope to run a test-strip with my hard tap-water this evening, but if it works (no calcium spots), I'm not sure that means anything.

    @PE: There are no mountains between me and the Pacific ocean, so we get an ocean breeze in the afternoon, moderating the summer heat. Pleasant. We also get wildfires and earthquakes. Unpleasant.

    @mikebarger: Here's the formula:

    Propylene glycol ............ 24 ml
    DimezoneS/Phenidone ......... 0.2 / 0.105 g (DimezoneS dissolves in 3-5 minutes)
    Sodium metaborate 4 mol ..... 6.7 g (dissolves in 3-5 minutes; turns orange)
    Ascorbic acid ............... 8.5 g (dissolves in 7-10 minutes; fizzes and turns clear)
    Propylene glycol to ......... 33.3 ml (final volume; should need to add little)

    Heat to 90C to dissolve everything and drive the water out of the metaborate.
    Dissolve in the order shown, and dissolve completely before adding the next chemical.
    To make one litre of developer, mix 33.3 ml of concentrate into water containing 90 grams of sodium sulfite. That's 1+29 dilution.
    The specific gravity is 1.18, so 33.3 ml of concentrate weighs 39.3 g, letting you measure it by weight if desired.
    Times are same as XTOL. Target pH is 8.33.

    Mark Overton

  6. #66

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    Quote Originally Posted by albada View Post

    A question for PE: The low densities in the graph and leaders imply underdevelopment, yet the short toe implies normal development. Can you explain this paradox?

    Mark Overton
    Mark, although I'm not PE (far from it), why wouldn't you expect this increase in compensating action at a 1+1 dilution vs stock strength? It seems right.

  7. #67

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    Thanks

    Quote Originally Posted by albada View Post
    My replies to postings:

    @Rudeofus: It has recently (2010) been discovered that metaborate sequesters cations such as Ca++. Search for "metaborate sequester". Here's a sentence from what appears to be the first report about this: "A form of borax known as metaborate has been found to sequester divalent cations such as Ca++ and prevent precipitation." The concentrate has a moderate amount of metaborate in it, so perhaps it can keep the calcium in check. How do I test sequestering of calcium and magnesium? I hope to run a test-strip with my hard tap-water this evening, but if it works (no calcium spots), I'm not sure that means anything.

    @PE: There are no mountains between me and the Pacific ocean, so we get an ocean breeze in the afternoon, moderating the summer heat. Pleasant. We also get wildfires and earthquakes. Unpleasant.

    @mikebarger: Here's the formula:

    Propylene glycol ............ 24 ml
    DimezoneS/Phenidone ......... 0.2 / 0.105 g (DimezoneS dissolves in 3-5 minutes)
    Sodium metaborate 4 mol ..... 6.7 g (dissolves in 3-5 minutes; turns orange)
    Ascorbic acid ............... 8.5 g (dissolves in 7-10 minutes; fizzes and turns clear)
    Propylene glycol to ......... 33.3 ml (final volume; should need to add little)

    Heat to 90C to dissolve everything and drive the water out of the metaborate.
    Dissolve in the order shown, and dissolve completely before adding the next chemical.
    To make one litre of developer, mix 33.3 ml of concentrate into water containing 90 grams of sodium sulfite. That's 1+29 dilution.
    The specific gravity is 1.18, so 33.3 ml of concentrate weighs 39.3 g, letting you measure it by weight if desired.
    Times are same as XTOL. Target pH is 8.33.

    Mark Overton

  8. #68

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    Tap-water results

    Rudeofus suggested that I try tap-water. Here's the graph of the comparison of XTOL versus the concentrate, using a test-strip of TMY2. The XTOL was dissolved in distilled water, but the concentrate was dissolved in tap-water, so XTOL had an advantage.

    Click image for larger version. 

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    The graphs are very close. Grain is the same, gauging in 22x loupes. My conclusion is: Tap-water had negligible effect.

    Also, I saw no evidence of precipitate before or after development, and my water is hard. That's good news, but I'd like to learn more about dealing with dissolved minerals.

    @Michael R: I'll confess that I've never tried 1+1 dilution before, so that graph is new to me. With that short toe, I can see why Tri-X is good for pushing.

    Mark Overton

  9. #69
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    Quote Originally Posted by albada View Post
    One difficulty is ascorbate is hard to find, so to clone XTOL, one must separately convert some ascorbic acid into ascorbate by adding sodium bicarbonate (baking soda). The problem with that is if the correct amounts of both ingredients are mixed, it will theoretically take a nearly infinite amount of time to convert all the ascorbic acid. To see why, suppose there is one molecule remaining of each ingredient. It will require perhaps years of stirring before those two molecules touch each other. So to complete the conversion in reasonable time, an excess of bicarbonate is needed. But what will that do to the developer?
    Mark Overton
    Mark, I know you wrote this a while ago, but I've been meaning to comment on it. I would be very surprised if (in general when reacting chemicals together), one needs to place greater quantities of one chemical in order to ensure sufficient reaction completion (assuming reaction rate time constants are not in the order of hours or days). I'm going to assume that the percent of reactant and product both change exponentially w.r.t. time. If so then the reaction will have a time constant (k), such that for a first order reaction,
    [A(t)] = [A(0)] exp(kt)

    unless k is in the order of hours or days (lets say it is in the order of seconds) then surely you will have sufficient equilibrium after a matter of minutes ? OK I just read here (Summary for reaction orders 0, 1, 2, and n) , that perhaps you have a zero order reaction. Is that the case ? In which case the product concentration only rises linearly not exponentially. Even then I don't imagine you would gain much time advantage by upping a reactant.

    Disclaimer: I'm a mathematician and electrical engineer, not a chemist !

  10. #70

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    Mark, Sodium metaborate 4 mol == NaBO2·4H2O ?



 

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