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  1. #21
    Photo Engineer's Avatar
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    Quote Originally Posted by Gibran
    ditch the photo flo if you wish and instead just use a tiny drop of liquid dish washing detergent in water to make your own photo flo. At least thats what an old RIT instructor once told me and he seemed to know of what he spoke. all you are doing is making a wetting agent to minimize streaks and spots on the film when drying. For some reason, I was once told not to use distilled water alone as a rinse.
    That old RIT instructor was WRONG!

    The chemical structure is generically right as one type of surfactant but ...

    That is a myth and I have posted information here and elsewhere and am trying to stop the continuing spread of that information. The scent and color added along with a lot of other things in any commercial washing detergent will leave an oily residue on film!

    Unless the detergent is unscented and uncolored it is unsafe to use with your precious film! The detergent should also be non-ionic for best results, otherwise it can cause a soap film to form on the surface of the emulsion as it will react with calcium ion in water and form a scum just like the soap scum you see in your bath or shower.

    Another potential myth is that distilled water can be used as a wash or final rinse to leave film clear of drying defects.

    To be exact about it, the water must also be DEIONIZED to remove any crud that has gotten into the distilled water from the metal pipes of the distillation equipment. This is generally not a problem, but I have seen it happen in some instances with dirty, corroded distillation equipment. You must test the quality of your DW first before you can use it flatly without exception.

    The DW should also be filtered, as some distillation devices tend to accumulate fungus growths and bacteria that can contaminate the DW with small threads and floaters. These can show up on film just like dust. Sometimes, being so small, they cannot be seen until you try to make an enlargement.

    So, this isn't a simple matter. No absolutes. Take some advice from one who has learned this from a technical standpoint and beware of all of the potential pitfalls. Don't fall for hearsay or guesses.

    PE

  2. #22
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    I forgot to add above that most detergents are alkaline, whereas film should be neutral or slighlty acidic in pH when dry. The alkalinity level of the detergent is important, as a detergent with a high pH can lead to softer swollen film. This may present a problem over the long haul, but IDK. No one has really tested it.

    PE

  3. #23
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    Quote Originally Posted by Photo Engineer
    I forgot to add above that most detergents are alkaline, whereas film should be neutral or slighlty acidic in pH when dry. The alkalinity level of the detergent is important, as a detergent with a high pH can lead to softer swollen film. This may present a problem over the long haul, but IDK. No one has really tested it.

    PE
    Well that information does surprise me as this teacher was very knowledgeable and not just repeating what he had heard. Of course he was also quite old so perhaps the liquid dishwashing detergents of old did not have the fragrences and colorants of those today. So, If one found a clear non fragrenced detergent, would it be safe? Seems like if you used a Hardening fixer that would solve the potential alkaline problem, no? Just curious as I have always just used Photo Flo myself.

  4. #24
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    Gibran, the best surfactant to use in a post process rinse is a neutral pH, nonionic surfactant solution containing no dye or scent.

    Ummmm. This sounds like Photo Flo and its counterparts by other manufacturers, all of which do the job! I cannot single out Photo FLo as being the 'best'. Just for example, the Formulary makes a very good surfactant which I have used among a host of others from other mfgrs.

    I don't know who your instructor was. I knew many of them there including Burt Carroll and Ron Francis as well as Bruce Kahn and Rich Hailstone. They are/were all excellent people and I don't wish to detract from some very good professional credentials here by implying any error.

    IDK what went wrong, but I suspect that you are right in your assumption. I do believe that the formulation of many detergents changed over time due to environmental factors. This probably upset a stable situation and started the myth.

    PE

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