seeking advice for mixing sodium sulfate and potassium alum

Discussion in 'B&W: Film, Paper, Chemistry' started by Sean, Aug 13, 2004.

  1. Sean

    Sean Admin Staff Member Admin

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    Hi,

    My Polaroid 665 pos/neg pack film has arrived so I am eager to make some 645 polaroid negs this weekend :smile:

    I also have the chem for making a negative clearing and hardening combo solution. This way I only need one clearing container in the field. This is Sodium Sulfate (yes sulfate not sulfite) and Potassium alum. I have the formula and the chemicals (they are in a very fine powder form). So, what temp should the water be, and I'm assuming I can mix them both at the same time? Also, are these chems highly toxic or anything to worry about? Thanks!
     
  2. lee

    lee Member

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    I have only used Sodium Sulfite for clearing Polaroid negs. Can't help you with the sulfate clearing agent.

    lee\c
     
  3. Ole

    Ole Moderator Staff Member Moderator

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    Sean, I haven't heard about that mix either. But I do know that if both your chemicals are sulfates (and they are), the order of mixing won't mater at all. Warm water will help, but isn't necessary.

    None of the chemicals are particularly poisonous, although the Alum will have the same effect on your skin as it does on the emulsion: Don't get it on your hands.
     
  4. ann

    ann Subscriber

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    like lee i have only used the sodium sulfite for clearing.
    When mixing alum for other processes i have discovered that it needs to be added slowly or it will clump up and not want to go into solution. However, this was quite a bit.
    Am curious, what is the formula you are using and where did you find it? Would like to know how well it clears, so feed back would be nice.
     
  5. Sean

    Sean Admin Staff Member Admin

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    Hi Ann, here is the info I am going by and I'll post results soon:

    http://www-unix.oit.umass.edu/~jpalma/pack_negative.html

    and the forumula in his writings:

    There is a non-official formula for clearing and hardening T-665 film. It is a combination clearing/hardening solution for Type 665 negatives that does not require the clearing bucket. It was published in an article in Popular Photography, November, 1976, and reported in Adams' book. This formula clears and hardens at the same time, and allows the photographer to carry around a smaller container of solution in the field and not worry as much about the negatives.

    Ingredient
    Amount (Metric)
    Amount (English)

    Potassium alum
    30 gm
    1 oz.

    Sodium sulfate (not sulfite)
    90 gm
    3 oz.

    Water
    1 L
    1 qt.


    Note that this formula uses sodium sulfate not sulfite. This formula can be used on Type 55 negatives if the 3 oz. of sodium sulfate are replaced with 60gm (2 oz.) of sodium bisulfite, but supposedly this solution has an "obnoxious odor." (Adams, p.299) All of these chemicals can be found at the Photographer's Formulary.
     
  6. Tom Hoskinson

    Tom Hoskinson Member

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    Sean,

    I have successfully used the sulfate/alum formula in the field (in a tupperware container) to clear and store Polaroid 55PN negatives. I mixed the chemicals in 125 deg F water, then cooled it to ambient before use.

    I still prefer pulling Polaroid 55PN film sheets out undeveloped and doing my processing when I get home.
     
  7. Ian Grant

    Ian Grant Subscriber

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    Well I've never thought of that

    But then I only use the film as a test in the field, after all it's far cheaper to use conventional materials if your processing back at base
     
  8. Tom Hoskinson

    Tom Hoskinson Member

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    If I'm doing exposure testing in the field, I generally don't use PN film for that - I use positive film.

    In any case, I'm currently shooting 8x10 sheet film for Azo contact printing and following Francesco's model: Do extensive testing, then shoot 1 sheet of film per scene and get it right the first time (or haul that big sucker back up the mountain and do it again).
     
  9. Sean

    Sean Admin Staff Member Admin

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    That's what I would prefer but I'm using the pack film on a MF Polaroid back, so there is no way to remove the sheets other than processing them. Glad to hear from someone who has used the sulf/alum solution :smile: