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  1. #71
    Rudeofus's Avatar
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    Quote Originally Posted by Relayer View Post
    Mark, Sodium metaborate 4 mol == NaBO2·4H2O ?
    I'll answer instead of Mark: Photo Formulary sells sodium metaborate which according to their MSDS is sodium metaborate 4 mol. This MSDS lists the formula NaBO2·2H2O [Na2B2O4·4H2O]

    Likewise there is a reference on http://www.borax.com which lists both 4 mol (NaBO2·2H2O) and 8 mol (NaBO2·4H2O) sodium metaborate. So for all practical purposes I would assume that Mark means the 4 mol compounds as defined by these references: NaBO2·2H2O

    The confusing names seem to come from the double compounds Na2B2O4·4H2O and Na2B2O4·8H2O
    Trying to be the best of whatever I am, even if what I am is no good.

  2. #72

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    Quote Originally Posted by Rudeofus View Post
    I'll answer instead of Mark
    thanks, but I have other question - what is the kodalk? )) sodium metaborate 4mol or 8mol?

  3. #73

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    http://www.film-and-darkroom-user.or...hp/t-5118.html
    See the last post.
    Ryuji gives Kodalk as 8-mol.This is CAS 1055 76 7
    The 4-mol is CAS 16800 11 6
    If Kodalk(or other suppliers 8-mol) is used this apparently necessitates a correction for the difference in molecular weight.
    Good spot Relayer.

  4. #74
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    Quote Originally Posted by Alan Johnson View Post
    Ryuji gives Kodalk as 8-mol.This is CAS 1055 76 7
    So does Grant Haist's book. And if Ryuji and Kodak agree on something, we can assume it's right. *ducks*
    Trying to be the best of whatever I am, even if what I am is no good.

  5. #75

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    Alan, thanks.
    just make some experiment - mix next solution like to Mark formula
    Water 1l
    Sodium sulfite 90g
    Phenidone 0.1g
    Ascorbic acid 8.5g

    because I haven't metaborate, I replace it with borax+sodium carbonate. 6.7g of Sodium metaborate 4 mol = 6.7/101.83 = 0.066mol. because 1 mol of borax have B4 (metaborate have B1) I take 0.066*381.37/4 = 6.3g of borax Na2B4O7·10H2O. mix and check pH=7.8
    after this I add 10% solution of sodium carbonate slowly and check pH. at pH=8.3 I'm stoping and calculate amount of Na2CO3 - its 2.33g/l. so result formula is:

    Sodium sulfite 90g
    Phenidone 0.1g
    Ascorbic acid 8.5g
    Borax 6.3g
    Sodium carbonate 2.3g
    Water 1l
    pH=8.3

    LegacyPro (Neopan) 400 @400 8min 21C (time from digitaltruth for XTOL stock) - negatives slightly dense than I expected. can't make comparison with XTOL because haven't it. Mark, maybe you can make this formula and test it.
    Last edited by Relayer; 07-22-2012 at 05:02 PM. Click to view previous post history.

  6. #76

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    @Rudeofus: You were right! An hour or two after I developed film in tap-water, keeping the used developer in a bottle, I noticed some cloudiness formed which became a finely powdered precipitate. I'm doing more experiments to see how long before the precipitate starts forming. If it's at least 30 minutes, it's probably not a problem. Otherwise, I have a problem. I'm also doing an experiment with metaborate in tap-water to see what happens.

    And thanks for answering Relayer's question about 4-mol versus 8-mol. Those names are confusing.

    @Relayer: If your developer using borax+carbonate had a pH of 8.3, then I think it should act the same as my developer. The digitaltruth times are starting points, and if it's "slightly dense", then the time was close. I suggest trying 7.5 minutes at 21C. Note that carbonate will not dissolve in propylene glycol.

    @PeterB: I think you're correct in that the reaction is 1st-order. But *both* reactants are declining in concentration, which I think results in a 2nd-order reaction and thus a different half-life. I'm a computer scientist, not a chemist, so I'll need to take some time to go through those equations.

    Mark Overton
    Last edited by albada; 07-22-2012 at 05:01 PM. Click to view previous post history.

  7. #77
    richydicky
    Thanks for the great work. I have wanted to try XTOL but it would be a waste making 5 litres. I am planning to buy the chemicals tomorrow to make a batch to your formula but I have just checked the supplier list and what they have is 8-mol sodium metaborate. Would appreciate the correction needed for the amount, my chemistry knowledge is over 30 years old!

  8. #78

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    Results of precipitation-tests in hard tap-water

    I mixed 50 ml of developer from sulfite and concentrate, and timed how long it took for visible cloudiness to appear when back-lit by a bare bulb. Temperature was 30C (summer and no A/C), but I think temperature does not affect the rate of precipitation-reactions, so the times below probably won't change with temperature.

    After 15 minutes: Developer was still perfectly clear.
    After 20 minutes: Faint cloudiness visible. It looked clear under normal lighting.
    After 30 minutes: More cloudiness, but solution still looked clear under normal lighting.
    After one hour: Cloudiness is still staying in suspension (not falling to the bottom). Looks slightly cloudy under normal lighting.

    My conclusion: With hard water, use the developer immediately after mixing. Or use purified water.

    BTW, I examined the test-strip developed with tap-water under the 22x loupe, and saw nothing unusual. I waited around 10 minutes before developing for 9 minutes, so I just missed the beginning of cloudiness. Also, in a different experiment, adding 10 g/L of sodium metaborate to tap-water never produced any cloudiness.

    I'll be exploring chelation agents. Thanks again to Rudeofus for suggesting that tap-water be tested. I had overlooked that. Do the chemists here have any comment about these tests and results? Any idea how severe the cloudiness must be before it starts affecting negatives?

    Mark Overton

  9. #79

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    Quote Originally Posted by albada View Post
    The digitaltruth times are starting points, and if it's "slightly dense", then the time was close. I suggest trying 7.5 minutes at 21C.
    I found original datasheet for Neopan400 from Fuji. 61/4 at 20C and 51/4 at 22C. compare to Kodak 81/4 at 20C. I think that 51/2-53/4 at 21C will be good for next attempt
    Quote Originally Posted by albada View Post
    Note that carbonate will not dissolve in propylene glycol.
    borax and carbonate dissolved in glycerin

  10. #80

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    Quote Originally Posted by albada View Post
    Temperature was 30C (summer and no A/C), but I think temperature does not affect the rate of precipitation-reactions, so the times below probably won't change with temperature.
    Temperature affects the rates of ALL reactions.

    The rule of thumb is that for every 10C increase in temperature, the reaction rate doubles. So a reaction at 30C will be twice as fast as one at 20C.

    Also, for precipitation, temperature affects solubility, so that affects the concentration that precipitation begins.

    Rule of thumb, solids are more soluble in water as the temperature increases. (The opposite is true for gases dissolved in water.)
    Kirk

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