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  1. #41

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    Quote Originally Posted by nworth View Post
    I wonder what a little bit of EDTA-Na would do for stability.
    As I stated before EDTA cannot be used since it actually catalyses the Fenton reaction. Don't know about NTA. This was the problem that Ryuji encountered. Which agents can be used and which cannot.
    A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.

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  2. #42
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    Then i would suggest NTA as a replacement for Salicylic acid for a trial run.

    NTA is used in Bleach iii for C41 IIRC. At least it was undergoing trials when I retired.

    Thinking this over for a bit, I have to add that you need more than the constants given above. You need to know the oxidation potential of the Fe III ion when complexed and when not complexed to make a full judgment.

    PE
    Last edited by Photo Engineer; 11-23-2011 at 08:17 PM. Click to view previous post history. Reason: Add paragraph at end

  3. #43

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    Success!
    The graininess and shadow-detail of the simplified DS-10 matches XTOL.
    BTW, this is the first time I've ever formulated my own developer. Nothing like learning something new when you're 54 years old!

    However, PE was right. pH was a surprise, and just 9g of ascorbic acid with 75g sulfite (per litre) pushed the pH lower than I thought (to 7.2). Adding a little borax didn't help enough, so I added some sodium carbonate to hit the target pH of 8.0. Here's what I ended up with:

    Phenidone ............... 0.15 g
    Ascorbic acid .......... 9 g
    Sodium sulfite ......... 75 g
    Borax ..................... 1.5 g
    Sodium carbonate ... 1.5 g
    Water to 1 L
    Develop for 10 min at 20C/68F.
    I'd like to reduce the ascorbic acid to 8 g/L (40:1 ratio with phenidone), and replace the alkalis with only borax or preferably TEA ... when it arrives in the mail in 6 days.
    It would be better to measure the phenidone more accurately. It's difficult even with an electronic gram scale with 0.01g resolution.

    Finally, I hope to dissolve most stuff in propylene glycol (a la PC-Glycol), yielding a developer that gives XTOL-quality at near-HC110 convenience.
    This is fun. Where have I been in the last 54 years?

    Comments are welcome.

    Mark Overton

  4. #44

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    Here is the formula of Gainer's PC Borax:

    Phenidone.....................0.15g
    Ascorbic Acid.................6.0g
    Borax decahydrate..........19g
    Water to.......................1L
    pH~9
    Develop for D-76 times.1L is said to process 12 rolls film.

    I have used this, it works well.
    It looks like you are on the way to making a somewhat similar developer but with added sulfite and lower pH to give finer grain.They usually put a little sodium metabisulfite in to make a buffer (Xtol,Mytol).
    Hope you reveal your next formula.

  5. #45

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    How exactly did OP evaluate the graininess, sharpness, speed and curve shapes for different contrast gradients in comparison to XTOL?

  6. #46

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    Hi Mark,

    There is a principle in chemistry which can be summed up as "Like dissolves like." What this means is that in general organic chemicals dissolve most readily in organic solvents and inorganic ones in an inorganic solvent. The Phenidone and ascorbic acid will dissolve in such solvents such as propylene glycol but everything else in your formula will not. When Kodak decided to develop HC-110 which contains no water, they were forced to use some chemical tricks pH was controlled using a mixture of TEA and DEA. Since they couldn't use potassium bromide they had to use an addition product of hydrogen bromide and an amine. These chemicals are not readily available and certainly not to the home experimenter. Some are also dangerous. If you look at the threads for glycol based developers on APUG you will find that they consist of developing agents and maybe TEA. They cannot contain sulfite or bromide and so have limited flexibility.

    Developing a useful developer is a very difficult task and requires a very good foundation in chemistry. The two chemists who developed Xtol worked for a year before they had a tentative formula that they could show to Kodak management. That's a lot of man-hours. For example, are you aware that for any developer with a superadditive combination of developing agents such as Xtol or D-76 that there is an optimal ratio of the two developing agents? You cannot just change the concentration of one agent willy-nilly and expect a good result.

    If you wish to continue experimenting then you will need a good book on photochemistry. Grant Haist's two books are the most current but there is also Mason and Glafkides.

    Good luck
    Jerry
    A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.

    ~Antoine de Saint-Exupery

  7. #47

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    Quote Originally Posted by Alan Johnson View Post
    It looks like you are on the way to making a somewhat similar developer but with added sulfite and lower pH to give finer grain.They usually put a little sodium metabisulfite in to make a buffer (Xtol,Mytol). Hope you reveal your next formula.
    Alan, thanks for the formula and the chemistry clues. I need chemistry clues because photochemistry and developer-engineering are new to me, as you'll see in my response to Gerald below. Yes, it looks like I'm heading toward a PC-Borax plus sulfite. I encourage you to try it first. /2

    Quote Originally Posted by Michael R 1974 View Post
    How exactly did OP evaluate the graininess, sharpness, speed and curve shapes for different contrast gradients in comparison to XTOL?
    Michael, my tests are so early and preliminary that no sensitometric (sp?) measurements have been done. I simply visually compared scans from a Nikon Coolscan on the monitor, where black-point/white-point/gamma were assigned identically in the scans.

    Quote Originally Posted by Gerald C Koch View Post
    <good information clipped>
    If you wish to continue experimenting then you will need a good book on photochemistry. Grant Haist's two books are the most current but there is also Mason and Glafkides.
    I have these books: Film Developing Cookbook, Darkroom Cookbook, Photographic Chemistry (Eaton, too shallow), and Photographic Processing Chemistry (Mason). I would love to get a hold of Haist's set, but his books cost a few hundred dollars (I've hunted for them). I suspect they are a better investment than classic cameras. or maybe that should be
    Anyway, Mason is by far the most thorough text I have, and I wish I had more information still. At your suggestion, perhaps I'll drop the $$$ into Haist's work. Which volume should I get? Well, I'm gathering many bits and pieces from the Internet. At this point, I only know some simple rules, and not even enough of them, such as the "like dissolves like" which you pointed out. My ignorance of photographic chemistry is frustrating, and I'm learning as fast as I can.

    Here's an idea I thought of while in the shower: Go ahead and add insoluble chemicals to propylene glycol or TEA. They won't dissolve, so they'll be in a suspension, and will settle to the bottom of the bottle. Before measuring out some concentrate, shake the bottle to get the insolubles back into suspension. I think this can only work if (1) those solids don't cake (stick) together when settled at the bottom, and (2) the viscosity of the concentrate is reasonably low to allow quick dispersion by shaking. Any thoughts on this? Should this idea go down the shower-drain from whence it came?

    Mark Overton

  8. #48

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    I was looking at something else recently, and I was reminded that oxalic acid is another excellent sequestering agent for iron. Oxalates were used in several early developers, but DK-93 is the only one that remains well documented. IIRC, it had pretty good keeping properties, but so does the related Rodinal. Has anyone explored this with ascorbic acid developers?

  9. #49

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    Quote Originally Posted by albada View Post
    Success!
    The graininess and shadow-detail of the simplified DS-10 matches XTOL.
    BTW, this is the first time I've ever formulated my own developer. Nothing like learning something new when you're 54 years old!

    ......

    I'd like to reduce the ascorbic acid to 8 g/L (40:1 ratio with phenidone), and replace the alkalis with only borax or preferably TEA ... when it arrives in the mail in 6 days.
    It would be better to measure the phenidone more accurately. It's difficult even with an electronic gram scale with 0.01g resolution.

    Finally, I hope to dissolve most stuff in propylene glycol (a la PC-Glycol), yielding a developer that gives XTOL-quality at near-HC110 convenience.
    This is fun. Where have I been in the last 54 years?

    Comments are welcome.

    Mark Overton
    Given you want Xtol quality with near HC110 convenience, you may want to mix up a small batch of PC-TEA. You'll have the ingredients to hand.

    My admittedly limited experience led me to thinking of PC-TEA as like a cross between Xtol and Rodinal, taking the best (for me) features of each. My more experienced friend likened it to the best of Xtol and HC110.

    Have fun with the experiments.

  10. #50

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    Quote Originally Posted by nworth View Post
    I was looking at something else recently, and I was reminded that oxalic acid is another excellent sequestering agent for iron. Oxalates were used in several early developers, but DK-93 is the only one that remains well documented. IIRC, it had pretty good keeping properties, but so does the related Rodinal. Has anyone explored this with ascorbic acid developers?
    Kodak supplied the developing agent paraminophenol as the oxalate salt under the tradename kodelon. Therefore their developers would naturally use this salt rather than the hydrochloride. We should not jump to the conclusion that there is any other reason for DK-93 containing a small amount of oxalate.

    Oxalic acid is a poorer chelating agent than salicylic acid. In addition we do not know whether it will inhibit oxidation or enhance it.
    A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.

    ~Antoine de Saint-Exupery



 

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