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  1. #121

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    The chemical maxim that like dissolves like is true. Borax, an inorganic salt, is insoluble in methyl alcohol, an organic solvent. Diols, where the two -OH groups are on adjacent carbons, such as the glycols presents a special case with borates in that they form borate esters. This increases the solubility. The large water of crystalization, 10H2O, also helps.
    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. #122

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    My earlier post was incorrect in that I said that sodium metaborate is borax. I really shouldn't post things late at night when I cannot sleep. What I should have written was sodium tetraborate. My bad.
    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

  3. #123

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    Concerning how much water is allowable in TEA before oxidation occurs, Pat Gainer originally suggested 100ml water per liter of TEA (this was a method he devised so that PC-TEA could be made at low temperature).I tried this and found it failed after 9 months.Pat Gainer then revised his recommendation to 10.2 ml water per 1000 ml TEA but I have not seen any reports on the keeping of this.Anyhow, 10% water definitely fails quite rapidly.
    It's in this long thread:
    http://www.apug.org/forums/forum37/2...brew-xtol.html

  4. #124
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    Anhydrous Boric Acid is soluble in low molecular weight alcohols and poly-alcohols such as PG and EG. Not very, but soluble nonetheless. Sodium salts of Boric acid are not very soluble and any solubility is probably due to the waters of hydration. Boric acid + TEA forms a salt which may or may not redissolve. I have not tested this. In any case PG is better than EG from a toxicological standpoint and either is better than antifreeze due to the anti-rust chemicals in antifreeze.

    The problem is that one must exclude oxygen and water from the concentrate. Kodak spent millions doing this and designing foolproof equipment to make hC110. Heating something on the stove can cause severe problems. When heated, and EG or PG mix with water in it can "bump" or create bubbles explosively when the temperature reaches or exceeds 100C. This can then cause the liquid to boil over and can create a fire if one is not careful. In addition, at this temperature EG and Phenidone create fumes that are not human friendly. Although the fumes from Phenidone are rather pleasant in odor, I don't believe you should subject yourself to the problem.

    You need alkali, an oxygen scavenger (antioxidant) and a silver halide solvent that are soluble in one common solvent without water. There are chemicals that fit these criteria and still allow admixtures with developing agents. I repeat again - this can be done.

    The adducts mentioned above may be available commercially and should be used if possible. This is the Sulfur Dioxide adduct of TEA and the HBr adduct of TEA. They can be home made at great expense and with great risk!

    PE

  5. #125

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    Quote Originally Posted by Gerald C Koch View Post
    Tronds,

    When heated sodium metaborate decahydrate (borax) will dissolve in its own water of crystalization. I suspect that something similar is happening with ethylene gycol in that the borax is dissolving in what is essentially a mixture of glycol and water. This points out a problem since the purpose of using glycols is to provide a waterless solution to prevent oxidation of the developing agents. Inorganic compounds with water of crystalization will defeat the concept of a water-free developer concentrate since they add water to the solution.

    Thanks for mentioning this.

    Jerry
    Let me see....... Where did I write heating or hot?
    Scanning my text.... .... .... .... .... ... .... Nope. Didn't write anything about heating.
    So, when I dissolved 20g borax in 75ml. etylene glycol WITHOUT heating, did it dissolve in it's own water?
    If so, just placing it in a bottle on the bench should give the same result. It should dissolve in it's own water.
    Surprise! It doesn't!

    Try to dissolve 20g borax in 75ml methylated spirits. (Denaturated ethyl alcohol 95%.)
    You can use as much heat as you want, but you can't make the borax dissolve "in it's own water" in ethyl alcohol.
    In other words: It won't work!

    From http://incidetech.net/tdsborax5mol.pdf

    When heated in a closed tube, SODIUM BORATE begins to melt in its own water of crystallization at 128oC (262oF) and
    is completely fluid at 140oC. Heated in the open, SODIUM BORATE loses its water of crystallization to complete
    hydration and fusion at 742.5oC (1367oF)

    Dissolving the borax was absolutely no problem. In fact, engine coolant DOES contain borax in it's concentrated form.
    Solubility in propylene glycol at 25C is about 30% according to what I can find.
    Solubility in ethylene glycol at 25C is 41.6%

    That is way more than 20g in 75ml, is there is no need for heating the glycol to dissolve it.
    Besides that, you need to heat the glycol/borax to 128C to make it dissolve in it's own water.
    When I can handle the bottle with my bare hands, it is in no way close to that temperature.

    So, how much water does 20g borax decahydrate contribute with?
    About 6.42g.
    In 100ml soluton this is about 6.42%
    Does this render the solultion useless for storing developing agents? I don't think so.

    What if you heat the ethylene glycol above 100c? Does the 6.42g of water evaporate?
    Yes, it will.

    So if you think this minute amount of water is a problem, just heat the glycol-borax solutuon above 100c fo some minutes.

    BTW, engine coolant glycol is designed to protect the engine components from oxidation. I suppose it will do the same for developing agents.
    In engines it protects from oxidation down to a concentration of about 30%. 6.42% water and 93.58% of etylene glycol mix is far more than 30%.

    Maybe, but just maybe it will reduce the shelf life from 10 years down to 9.5 years, but I don't care. If I can't use 100ml of PC-glycol in 9 years, I just have to mix caffenol the few times I need to develop a film.

  6. #126

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    Quote Originally Posted by Gerald C Koch View Post
    The chemical maxim that like dissolves like is true. Borax, an inorganic salt, is insoluble in methyl alcohol, an organic solvent. Diols, where the two -OH groups are on adjacent carbons, such as the glycols presents a special case with borates in that they form borate esters. This increases the solubility. The large water of crystalization, 10H2O, also helps.
    Fascinating exception to the rule.
    Here are a couple of tidbits that I forgot to mention which support what you said:
    • borax.com states that 21.53% of borax pentahydrate can be dissolved into PG (weight/weight). I don't know about decahydrate. Also, I'm leary of putting any borax into PG because of the H2O, and that's partly why I avoided it in my proposed developer from yesterday.
    • Boric acid is commonly mixed with PG in insecticides used to treat wood such as Bora-care, Penetreat and Timbor.

    My question: Will the borate esters affect the functions of boric acid and sodium metaborate in a developer?
    I think prior postings have already said "maybe" regarding boric acid, but how about metaborate?

    Anyway, if borates dissolved in PG will function okay, then that's a good tool to have in our toolkit.

    PE: Thanks for the warning about heating PG to 100C. What temperature do you think would be enough to drive out the H2O? When dissolving components into PG, I'd like to use a temp that's hot enough to keep H2O out, but no hotter.

    Mark Overton

  7. #127

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    Quote Originally Posted by albada View Post
    PE said inorganics should precipitate out. Could you try heating a sample of this mixture to 100C to drive out any water? Also, you can measure the volume or weight of the sample before and after heating to test whether some water was lost. I'm curious about this.

    Best,

    Mark Overton
    I didn't heat it to dissolve the borax, but I had to heat a bit to dissolve the lye pearls and the sodium ascorbate. Not more than 50c though.
    When heated and cooled again, it stayed in soluton, nothing precipitated out.

    Heating to more than 100c will drive out any dissolved water, but since the engine coolant is designed to protect the engine components from oxidation, even in a 30% mix with water, I think this will be quite fine with the 6.42g of water introduced by the borax decahydrate.

    Besides that, you need to heat the glycol-borax soluton to above 128c to split the water from the borax molecules. Storing at 20c or even 30c is quite safe if you think of it. This according to the datasheets for borax.

    In an eralier attempt, where I tried to introduce 2g sodium metabisuphite in the solution. That won't dissolve. Adding 5ml of water made it possible to dissolve some of it, but not all of it.

    Borax has the ability to bleach out colour of liquids. In the version with 5ml of water, it lost it's blue-green colour in 24 hours.
    Without adding the 5ml of water, nothing happened.

    Both versions is stored in bottles, so I will test both after 6 months, and after a year if both are still active after the 6 month period of storage.
    The version with water and sulphite may loose its power, but then again, the sulphite and other components in the angine coolant may in fact preserve it.
    Only testing will show what is happening over time.

    What puzzles me is why is propylene glycol choosen as a container? Concentrated blue engine coolant is easier to get and may in fact be better suited to the task.

    Trond Solem.

  8. #128

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    About borax, glycol and formation of esters, and why the pH is lower than 9.2

    This post explains a lot about what happens when dissoving borax in glycol.

    http://www.apug.org/forums/viewpost.php?p=825183

  9. #129

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    Quote Originally Posted by Tronds View Post
    What puzzles me is why is propylene glycol choosen as a container? Concentrated blue engine coolant is easier to get and may in fact be better suited to the task.
    Trond Solem.
    First, thank you for contributing to this thread. I seem to remember that you are the creator of the excellent Caffenol blog. Is that true?

    I chose propylene glycol because it's much less toxic than ethylene glycol. Also, the engine coolants available in America (are you in Europe?) have many additives in them, and I don't know what they'll do in a developer. So I was forced to order the glycol online, and PG is easy to buy online.

    I'm keeping a list of chemicals that can dissolve in PG:

    Phenidone to >= 2% (g/ml)
    Ascorbic acid to >= 20% (g/ml)
    Hydroquinone to >= 20% (g/ml)
    Borax deca/pentahydrate 21.53% weight/weight (25C)
    Boric acid (in insecticides)
    Sodium metaborate
    Citric acid
    Benzotriazole
    Do you know of more developer-chemicals that are glycol-soluble?

    Mark Overton

  10. #130

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    Metol and Glycin.They have to be reacted with small amounts of TEA and water first, as described in the mixing instructions for Pyrocat-MC section F:
    http://www.pyrocat-hd.com/html/mixing.html



 

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