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  1. #21

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    Quote Originally Posted by DeanC
    Okay, the second batch is in the process of cooling down enough to take the catechol and phenidone now. It looks like all of the metabisulfite and bromide went into solution but the liquid is cloudy/milky now instead of clear (but it doesn't appear to settle out when I stop stirring so I think everything is disolved.) Should I be concerned about the cloudyness or should I just finish mixing and give it a try on a negative once it's cooled?

    Thanks again,
    Dean
    Just give it a try after mixing in the pyrocatechin and phenidone. Slight clouding at this point is not unusual.

    Sandy

  2. #22

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    Quote Originally Posted by Jim Chinn
    .....Doesn't Pyrocatechin have a very low vapor point, something around room temperature? I seem to remeber a warning somewhere about being carefull about inhaling catechol before it goes into the solution.
    This figure for vapor pressure quoted by Sandy (at 167degF) is low. Also, if a substance can stand that degree of heating without chemical change and without evaporating, which pyrocatechol apparently can, then vapor at room temperature will be miniscule. However, fine particles of powdered chemical can still become airborne easily, hence the usual warnings about breathing it in or spreading it around.

  3. #23

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    Quote Originally Posted by DeanC
    Thanks Sandy, I'll give it another try today.

    Also, just in case someone hasn't said it here lately, thank you for being the incredible resource for the analog photo community that you are. Hurry up and publish a book on this stuff so we can all go out and buy a copy, would ya? ;-)

    Dean

    Thanks, and I am working on a book. Takes time, though. Let's just hope that by the time we finish the book there will still be film!!

    Sandy

  4. #24
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    Quote Originally Posted by sanking
    Just give it a try after mixing in the pyrocatechin and phenidone. Slight clouding at this point is not unusual.
    Just finished trying both it and the first batch from last night that had the solubility problem. Looks like all the metabisulfite went into solution overnight...

    Just eyeballing the two negatives (4x5 step wedges contact printed onto 4x5 FP4+) they both look identical and appropriately developed (2:2:100, 70F, 11min rotary.) I'll throw them in the densitometer when I get home from work tomorrow night to be sure, but I think I've got 2 good liters of Stock A. That should be enough to last me while, eh?

    Thanks for all your help,
    Dean

  5. #25

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    Quote Originally Posted by DeanC
    ... Looks like all the metabisulfite went into solution overnight...
    Would plenty of time be a substitute for heating?

  6. #26

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    Does anyone know what the capacity of PC-HD is? i.e. square-inches of film per litre of working solution.

    Thanks,

    Tom

  7. #27

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    Quote Originally Posted by Tom Kershaw
    Does anyone know what the capacity of PC-HD is? i.e. square-inches of film per litre of working solution.

    Thanks,

    Tom
    All of my testing (which is in BTZS type tubes with constant agitation) is based on the use of 75 ml of the 1:1:100 working solution per twenty square inches of film, or a sheet of 4X5" film. This amounts to a minimum of 250 ml of developer per sheet of 8X10" film.

    One might be able to get away with slightly less solution, but at the risk of longer development times and perhaps slightly increased B+F from general stain.

    Sandy

  8. #28
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    Quote Originally Posted by DeanC
    Just eyeballing the two negatives (4x5 step wedges contact printed onto 4x5 FP4+) they both look identical and appropriately developed (2:2:100, 70F, 11min rotary.) I'll throw them in the densitometer when I get home from work tomorrow night to be sure, but I think I've got 2 good liters of Stock A. That should be enough to last me while, eh?
    Looks like the first batch (the one where it looked like the metabisulfite hadn't dissolved all the way at first) developed my test sheet out to an avg. gradient of 0.77 and the second batch (the one that looked a little cloudy) developed an identically exposed sheet out to an avg. gradient of 0.71. Both measured on the blue channel of my densitometer.

    Seems like they both work with the first solution being slight more active.

    Dean

  9. #29

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    Quote Originally Posted by DeanC
    Looks like the first batch (the one where it looked like the metabisulfite hadn't dissolved all the way at first) developed my test sheet out to an avg. gradient of 0.77 and the second batch (the one that looked a little cloudy) developed an identically exposed sheet out to an avg. gradient of 0.71. Both measured on the blue channel of my densitometer.

    Seems like they both work with the first solution being slight more active.

    Dean
    The slightly greater activity could also be due to the fact that some of the potassium bromide did not get completely dissolved in the solution. I find that the bromide is even harder to dissolve than the metabisulfite. Slightly greater activity would be expected if that were the case.
    Sandy

  10. #30
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    Quote Originally Posted by sanking
    The slightly greater activity could also be due to the fact that some of the potassium bromide did not get completely dissolved in the solution. I find that the bromide is even harder to dissolve than the metabisulfite. Slightly greater activity would be expected if that were the case.
    Sandy
    Interesting. So the bromide restrains the activity somewhat? I guess I'll hang onto both batches and just make a note somewhere that when I switch to the second I should bump up development time by about 10%...

    Dean

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