What's in a Polaroid print coater?

Discussion in 'B&W: Film, Paper, Chemistry' started by okto, Apr 13, 2008.

  1. okto

    okto Member

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    I looked up the MSDS for the print coater goo, and got the following info:

    Isopropanol/Isopropyl alcohol, 5-15%
    Zinc acetate dihydrate, 2-5%
    Glacial acetic acid, 3-7%

    However, not only are these percentages VERY approximate, but the MSDS is not required to list "chemicals present in the mixture in concentrations below 1% which are considered not to be a hazard", so I may be missing some essential ingredients.

    Does anyone know the full ingredients list with concentrations for the Polaroid print coater? Many of the ones I find in old film boxes are dried up, even though the developer pods in the film often aren't because they're inert-gas packaged. (Why did no one think to do that with the coater?)
     
  2. Photo Engineer

    Photo Engineer Subscriber

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    I used to know, but have forgotten. I do know that it contains an organic heterocyclic compound, that is, more specifically it is a ring system with nitrogen and carbon. It may be a piperazine or piperadine compound or something like that. It is what gives it that strange peppery odor. There is also a lacquer and another solvent there.

    That is all I remember for the coater that goes onto a finished B&W print.

    PE
     
  3. Cruzingoose

    Cruzingoose Member

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    Print Coater Goo

    I've used regular rattle-can spray lacquer on many of my prints for just the same reason and 15+ years they are still good with no deterioration.
     
  4. Photo Engineer

    Photo Engineer Subscriber

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    Well, actually, Polaroid silver prints are subject to dichroic fog or bronzing if the pH is not right and if they are exposed to oxygen, and this is why they apparently need a stabilizing agent. That is what the print coater is for. I suppose that lacquer may be ok, but IDK. Never tried it. Our coaters used to dry out and I asked about the contents of the coater so I could make my own. I was treated to a lengthy description of the reasons for it and the contents but this is about 40 years ago so I have no memory of it except what I said above. It is apparently a lot more complex than the MSDS would lead one to believe.

    I don't think Polaroid would go to all of that trouble if it was not useful in some way.

    PE
     
  5. okto

    okto Member

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    Glad to have a chemist (or at least someone knowledgeable about chemistry) involved, as I know very little.
    I have heard before that the coater contains piperadine, so we can safely assume that's in there. The real question is the concentrations. 5-15% is a pretty wide range.
    I wonder if anyone could get ahold of the Australian MSDS, I have heard that Australian regulations for what must be included in the chemical breakdown are much more strict.
     
  6. AgX

    AgX Member

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    I am not sure which coating you are referring to exactly, but in the 7th edition of the Neblette the washing/stabilizing/isolating issue concerning Polaroid diffusion-prints over their history is treated in an own small chapter, though not going much into chemical detail.