The impossible project: latex timing layer?

Discussion in 'Silver Gelatin Based Emulsion Making & Coating' started by vdonovan, May 6, 2009.

  1. vdonovan

    vdonovan Subscriber

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    The website for the Impossible Project, attempting to re-formulate and re-start production of Polaroid 600 integral film, has been updated. The most interesting update is a request for help sourcing a particular type of latex to use as a timing layer. There's a diagram on the website of the film layers, as well as a cryptic (to me) discussion of the chemistry.

    I'm be interested in the comments of photo chemistry experts here as to what they can glean from the I.P.'s request.
     
  2. AgX

    AgX Member

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    Between the image receiving layer and the clear cover sheet is situated an alkali-sink. Being acid itself it neutralizes the alkali of the developer. And thus stops the development, a bit like the stop bath in classic development.

    The time it takes the alkali to reach this sink is controlled by a timing layer. One can either use a layer with constant permeability or a layer which is corroded in a way by the alkali and will `break´ after some time. The latter resembles more the classic processing where solutions are exhanged in short time.

    To my understanding of the request they intend to use a double layer, as the latex (intented as barrier) is to be coated on gelatin and not directly on the polymeric acid layer.

    The difficulties the manufacture of this part of the layer-assembly would form has been hinted at by PE at the initial discussion of the Impossible Project.
     
  3. Photo Engineer

    Photo Engineer Subscriber

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    If you could give a URL that would help me study their particular situation.

    Basically, AgX has it right. I used to work on timing layers and shutdown layers at EK on some special projects and I know how very hard it is to get this right. Basically, the latext is coated over a polyacrylic acid copolymer. The latex coating must be penetrated before reaching the acid which stops development. This timing layer is critical to getting good pictures and must respond properly over a wide range of temperatures or the pictures will not come out right. Polaroid had a lot of problems with color shifts for this reason.

    But, the bottom line is this. Too many of the original materials needed to make Instant products were made just for those markets and have now vanished. This will make recreation a hurculean task. I wish them well.

    PE
     
  4. AgX

    AgX Member

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  5. Photo Engineer

    Photo Engineer Subscriber

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    Thanks.

    You will note that the image is on top of the timing layer. Kodak's system was not. Therefore, in this case, the entire imaging layer must remain intact and hard. This is the critical issue I think. The latex must be hardenable as well as the acid layer and the recieving (mordant?) layer. The gelatin is rendered very soft by the base and so the hardening must be effective.

    Kodak made their own latexes. Maybe a search of the patents might help. There are several latexes or near latexes that might help, but they are all custom made items. Therefore, they would probably be expensive. I know that one of the Kodak ingredients was found to be a carcinogen and had to be eliminated from the project, so that is another consideration.

    I found another route to the solution, but that is not applicable here as they need timing as well and hardening.

    They have a lot of work ahead of them.

    PE
     
  6. PHOTOTONE

    PHOTOTONE Member

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  7. Photo Engineer

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    I have not done any of that sort of work since the 80s. I've forgotten most of the details of the timing and acidification layers, but do remember some of the test procedures. I'm afraid that I would be of limited value to them. They have all of the retired or laid off Polaroid people to draw on besides.

    Besides, I'm not really interested. I have too many other things to accomplish that I can do with better impact on the future of analog. I think that you can see the importance of that single point.

    PE
     
  8. vdonovan

    vdonovan Subscriber

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    Thanks PE and AGX. This is just the discussion I was hoping would break out. I always learn something new on APUG!
     
  9. AgX

    AgX Member

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    Impossible states that they

    "...could produce the very first complete and stable instant picture a few weeks ago".
     
  10. Photo Engineer

    Photo Engineer Subscriber

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    If there is such a demand for it, why didn't they? :smile: After all, they could have sold it!

    PE
     
  11. Michael W

    Michael W Member

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    Due to your incredible support regarding the 5th of our 7 big challenges (the latex timing layer), the team could produce the very first complete and stable instant picture a few weeks ago - a round of applause everybody!!

    That is to say that development is making really good progress at the moment, we're ahead of the original production timeline and have not found any unsolvable roadblocks ahead.


    That's the full text from their site; the snippet a few posts back was a little enigmatic
     
  12. AgX

    AgX Member

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    Sorry, I should have corrected their inappropriate use of the word could into `succeeded in´...

    Now back to technology.
     
  13. Ray Rogers

    Ray Rogers Member

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    Hi AgX.

    I was wondering what those 7 Challenges were....

    I recall mentioning their funky web site earlier and it has not improved...
    I do not remember if we ever figured it out, but their web page still confuses me...

    Well... using a strange kind of hopscotch logic,
    I think I fiigured out what they are on about... simple simple simple.

    I have now guessed that their "7 Challanges" are
    the 7 different layers to the film:

    1. Negative base
    2. Negative Coating Layer
    3. Pod developer
    4. Image Receiving
    5. Timing layer
    6. Acid polymer
    7. Clear polyester

    (Did we clear this up earlier, or is this the first description of the 7 challenges?I know we talked about it before, but can't recall how or if it was resolved!)

    Anyway, I have a potentially suitable latex here with me... Does anyone know which latex they found or where it was sourced?
    If it is different, they might want to compare....

    Ray
     
  14. AgX

    AgX Member

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    I can't answer any of your questions.
     
  15. E76

    E76 Member

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    I have to wonder where the battery fits in to all this. Polaroid made their own "Polapulse" to fit within the cartridges. Where do they expect to source them? The recreation of the film presents bigger challenges to be sure, but the battery is pretty important.
     
  16. AgX

    AgX Member

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    This is indeed a major problem. The production of those special batteries has been outsourced by Polaroid in the beginning but then done in an own plant.
    However battery technology has evolved over time. So they might use an array of stock types.
     
  17. AgX

    AgX Member

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    In a BBC World Service article on the company it is referred to 8 films per pack, in case this is not an error of the journalist, this might be due to that battery problem.
     
  18. EASmithV

    EASmithV Member

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    What is?
     
  19. PHOTOTONE

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    The battery may be thicker, thus allowing only 8 films per filmpack instead of the 10 films in typical Polaroid film pack.
     
  20. AgX

    AgX Member

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    I just realized that this content of only 8 films is not new at all.
    The recent SX-70 manipulatable version also contained only 8 films.
     
  21. Aurum

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    Battery tech has evolved leaps and bounds since the polaroid pack battery was developed. You can even get battery tech thats paper thin (Powerpaper.com).

    Battery size would realistically come down to minimum order quantities and price, if needs to be a custom job