Why I use Photo Flo 200

Discussion in 'Silver Gelatin Based Emulsion Making & Coating' started by Photo Engineer, Oct 10, 2010.

  1. Photo Engineer

    Photo Engineer Subscriber

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    The attached pictures show why! I am taking HRSTs advice! :wink:

    Kodak had patented an addendum that increases speed and contrast of a given emulsion. The pictures below show examples of an AgBr emulsion with 3% Iodide and a Sulfur finish that compare surfactant X and Photo Flo 200 used as surfactant.

    The results show that there is an ingredient in Photo Flo that is covered in that patent (well, I knew that :D ) ! The results are about 1/2 stop in speed and about 1/2 grade of contrast. These two photos were identically exposed and processed.

    This does NOT work with several other emulsions that I tried, but it does work with this one on a repeatable basis. There are several other compounds that do the same. I hope to report on them as well.

    PE
     

    Attached Files:

  2. hrst

    hrst Member

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    Thanks! Interesting. Was the surfactant added just before coating? How can it cause an increase in speed like this? And why is this compound in Photo Flo 200 in the first place?
     
  3. Photo Engineer

    Photo Engineer Subscriber

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    It is added as a normal surfactant just before coating. It is used at the normal level. If it is not, then coating defects result.

    IDK why it causes the effect. It is a development accelerator though, and that is all that I know. I was directed to the patent by a friend after I observed the effect. It can be attributed to either Poly alcohols and / or poly ethers. I have no more information at this time, but hope to get some at the end of the month at our next GEH lunch.

    See what happens when I take advice? More work for me! :wink:

    PE
     
  4. wildbillbugman

    wildbillbugman Member

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    PE,
    Isn't Photo Flo 200 diluted Triton X200? I remember looking at the structure of the latter ( in Sigma-Aldrich, I think). It has 1 sulfur atom. Perhaps this is a source for acceleration. Just a thought from a rank amateur.
    Bill
     
  5. Jeff Kubach

    Jeff Kubach Member

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    I have use Photo Flo 200, like it very much!

    Jeff
     
  6. Photo Engineer

    Photo Engineer Subscriber

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    Photo Flo 200 contains Triton X 100 plus several other ingredients. It contains no Sulfur atoms.

    PE
     
  7. richard ide

    richard ide Member

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    That is really neat. Thanks for this and all your other posts.

    Regards
     
  8. clayne

    clayne Member

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    So what are we saying here? That the use of photoflo increases the apparent film speed after the fact? Or is just an emulsion coating related property?
     
  9. Photo Engineer

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    An emulsion coating property AFAIK. If it works after the fact, that is a bonus! :wink:

    PE
     
  10. alexhill

    alexhill Member

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    This is interesting! I've got to coat some glass soon, so I'd like to give this a try. how are you applying the photoflow to the glass?

    I'll take a guess. Clean the glass, the submerge in photoflow (mixed to the right dilution) then let dry before coating?
     
  11. bblhed

    bblhed Member

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    I always knew Photo Flo wasn't just soap, and I use it because my water is hard, but this is another reason to use it. You wouldn't happen to know the exact mix amount of Photo Flo for 16 fluid Oz of water would you? I feel that "to the line on the inside of the cap" is a little less than repeatable. Actually the Photo Flo mixing is the part of my process that I can't do the same every time.

    Thanks for the info.
     
  12. Photo Engineer

    Photo Engineer Subscriber

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    The surfactant, when used, is added to the melted emulsion along with the hardener just before coating and is held at 40 deg C during the entire coating session.

    This method does not work with all emulsions, and Photo Flo is not the best surfactant for use on glass as has been pointed out by Denise Ross and Mark Osterman. If used, it may need to be "assisted" by another surfactant.

    PE
     
  13. Photo Engineer

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    This method is NOT for use in processing emulsions. It is used in the making and coating of an emulsion.

    Photo Flo dilution in water for processing is contained in the name. Photo Flo 200 is thus diluted 1:199 and Photo Flo 600 is diluted 1:599. For use with emulsion coating, the level must be determined by the coater. I use 1/2 ml for every 200 ml of 10% gelatin.

    PE
     
  14. Gerald C Koch

    Gerald C Koch Member

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    Years ago when glass plates were popular, the glass was briefly etched with hydrofluoric acid. The amount of etching was invisible to the naked eye but provided a tooth for the adherence of the emulsion. If you decide to try this please observe safety requirements for this acid.
     
  15. Ian Grant

    Ian Grant Subscriber

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    The method of adding a specific surfactants as developer improvers, not just as wetting agents, has been used in developers in the past and some almost certainly still use them. Agfa, Ilford, Kodak & Fuji all have Patents covering their use.

    So the answer to Clayne's question is probably yes in theory, but very likely less so in practice because it would be better to add them at the emulsion coating stage which gives greater benefits/effects.

    Agfa's 1930's work on surfactants as an aid to elimination air bubbles threw up unexpected results which triggered a number of Patents. Somewhere I have the details and references.

    Mason touches on the subject without giving much in terms of references except to work by James (at Kodak).

    Ian
     
  16. bblhed

    bblhed Member

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    I thank you not only for setting me straight on that, but also for providing me with an off topic (not that I knew I was off topic) answer that is so simple I will never forget it. I will get a measuring device (medication syringe for children's oral medication) and add it to my kit.
     
  17. Photo Engineer

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    Ray, this was an idea which was "discovered" by many companies at about the same time. I have used many surfactants for controls as well as none.

    PE