Calling all chemists

Discussion in 'Color: Film, Paper, and Chemistry' started by Nick Zentena, Mar 2, 2005.

  1. Nick Zentena

    Nick Zentena Member

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    I'm getting closer to ordering my chems for the E-6 stuff.

    The first developer uses phenidone. Can I just sub metol instead? Adjusting by using 10X the amount of metol instead of the phenidone in the formula?

    Can I use Sodium Borohydride in the reversal bath instead of potassium borohydride? If so what sort of adjustment?


    edta na 4 is EDTA Tetrasodium?
     
  2. Jorge

    Jorge Inactive

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    yes you can substitute metol.

    Uh...are you sure it is sodium borohydride? Sodium borohydride is water reactive, it will generate a flame. You better make sure this is the right ingredient.

    yes Na4 is EDTA tetrasodium.
     
  3. Donald Qualls

    Donald Qualls Member

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    Can't help you with the borohydride (though it hasn't been that many years since a reversal exposure was used before the color dev, no foggant needed), but I can tell you that any developer that will give you the right contrast will work in the first dev. That said, be prepared to expend a lot of film on testing to get the first dev right if you start changing the formula; you'll have to (almost) start all over fresh on the first dev times. Yes, metol at 10x the phenidone will be close, but might require adjusting pH or exact metol quantity to get it right, or else adjusting the first dev time...

    You don't need to worry about grain etc. in first dev, of course -- all that silver gets bleached out anyway, not even a dye cloud to show for its ever having been there. All you're concerned about is getting the contrast and speed right, and likely not taking all day (though at E-6 temperature, that shouldn't be a major problem). Oh, and not leaving too much undeveloped silver in the highlights, which will show as fog in the reveral/color dev...

    Might be interesting to try HC-110 as a first dev...
     
  4. Nick Zentena

    Nick Zentena Member

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    No the reversal formula is:

    Stock solution:
    0.2 g potassium borohydride
    10 g sodium hydroxide
    Water to make 100 mL

    Start with COLD water, dissove the NaOH (it will get warm).
    Put in KBH4.
    Add water to make 100 mL

    Working Solution:
    12 mL Stock Solution
    Water to make 1 L

    The potassium borohydride is kind of expensive so was hoping the sodium could be used. I guess I could use light instead of the chemical bath.

    I'd rather use metol because I already have it and I get the impression phenidone doesn't keep.
     
  5. Jorge

    Jorge Inactive

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    How much sodium borohydride will you be using? or IOW how much pot BH4 does the formula need? You might be able to use the sodium salt if you dissolve it in very small amounts and do so very carefully.
     
  6. Ole

    Ole Moderator Staff Member Moderator

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    With that mixture ratio between potassium borohydride and sodium hydroxide, I can't see why the difference between sodium and potassium could be significant. Molar weight is different, so be sure to make your conversion properly - and maybe substitute a pinch of KOH for a pinch of the NaOH just in case.


    I checked: You'll need 0.14 gram NaBH4 to replace the 0.2 gram KBH4.
     
  7. Jorge

    Jorge Inactive

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    Oh Heck, if all you are mixing is 0.14 grams, go for it. As Ole said it is not a significant amount and will not represent any danger.
     
  8. Nick Zentena

    Nick Zentena Member

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    Cool-) The supplier's smallest size is 60 grams for $90. That's a life time supply but if it doesn't turn out right -( The sodium is a little cheaper and comes in smaller sizes to.

    Thanks
     
  9. Maine-iac

    Maine-iac Member

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    Phenidone keeps just fine, both in the powder form and in stock solutions where the powder is mixed either with isopropyl alcohol (at least 90%) or propylene glycol. It will keep indefinitely. My little jar of Phenidone powder that I use to mix the stock solutions has been around since Noah came off the ark, and it's still potent.

    Larry
     
  10. Jordan

    Jordan Member

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    Coming to this one late, but... potassium borohydride in organic chemistry is a bit less reactive than the sodium version. But this is in organic solvents and when organic reductions are being performed. For the reversal process you just need a general strong reductant and I don't think it would make a big difference, although you may need a little longer in that particular bath.
     
  11. Photo Engineer

    Photo Engineer Subscriber

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    The E6 process does NOT use any borohydride. The E6 process uses stannous chloride (tin chloride). It also does not use hydroquinone.

    Substitutions can give inferior results.

    PE