Ultrasound agitation?

Discussion in 'Film and Processing' started by michael_cirelli, Jan 15, 2017.

  1. I was wondering if anyone has ever heard of or tried using ultrasound to agitate while processing film?

    I am going to attempt to build a semi-automated film processor and was trying to figure out how to go about agitation with ought building
    some elaborate rotary device. The thought of ultrasound came to me when using an ultrasonic jewelry cleaner. Any thoughts?

    Thanks for any input!!

    -Mikie
     
  2. If you try it, keep us posted. I wonder if it would be disruptive to the emulsion when softened? Temperature drift was an issue on a process I was involved in awhile back using ultrasonic horns in diamond slurries and it required cooling. We needed the ultrasonic when mixing .25 micron diamonds to keep the diamonds from agglomerating. The process wasn't nearly as critical (temperature-wise) as film chemistry but it still presented problems in keeping things cool enough.
    I also recall dissimilar materials reacting in strange ways in ultrasonic baths. They try to separate from each other. Maybe you would be operating in low enough levels of energy that these problems wouldn't present major problems?
     
  3. Hi, I've worked with a lot of processing machines over the years, and never heard of ultrasonic vibrations being used for
    agitation in a commercial machine.

    The concept was not unknown, though. I do have a copy of an old paper published Oct '66 in the journal of the SMPTE, by
    Snyder of Kodak's Photographic Technology Division, that investigated agitation in continuous film processors. One of the
    methods used an ultrasonic transducer off to the side of the film. They found significant "streaking" on the film, running at
    21 ft/min. The only conclusion was, "Ultrasonic agitation at these conditions does not seem to be as effective as agitation
    by spray nozzles." (Note that the "spray nozzles" were submerged.)

    I don't have any experience with ultrasonic. The method we used in our cine machines, running up to about 50 ft/min, was
    always via submerged spray nozzles, aka "turbulator bars." With a new machine best flow rates were found by trial and
    error, and once established gave excellent results.

    Best of luck with your project.
     
  4. Reactions occurring at a surface between a solid body (film) and a solution can be affected if the reaction products or reagent are not being frequently removed (reaction products) or replenished (developer) in order to maintain the reaction under optimum conditions. This is true for many chemical systems and most likely for photographic processing. Ultrasound may disturb that surface and the chemicals involved, but I question whether its short distance effect is enough to move chemicals over the distances required to remove or replenish them. Good old shaking or rocking mechanical motions are probably still the best agitation methods to achieve the result in home processing.
    Having said that, the fly in the ointment is nonetheless the question of why stand development (absence of agitation) results in development? Time for a little Googling...
    OK, I found this quote on lack of agitation (stand development): "Without agitation, stand development can suffer from bromide drag. The developing process produces bromide ions, which settle towards the bottom of the developing tank. In doing so they create streaks of uneven development on the surface of the film" (Wikipedia source). I think it confirms the notion that sufficient agitation is useful in avoiding such effects, while not necessarily ruling out very short distance agitation as a method of that.

    One of the advantages of manual agitation is that it keeps me awake, busy and aware of the total process time, whereas something like ultrasonic agitation and without a process timer to stop it might have the opposite effect.
     
  5. If you going to use an ultra sonicator to agitate the developer in the processing tank most likely you are going to dislodge the film emulsion from the plastic surface. I would not do it. And you have to use hearing protection while processing film. Do not do it.
     
  6. Agitation is more about large scale motions.
    As I understand it, production machinery uses blasts of nitrogen or air for agitation.
     

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