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Motion picture agitation during development

developing agitation color film

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#1 Philip Kral

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Posted 22 May 2017 - 04:01 PM

Strange question for those members who own and/ or work in motion picture film labs: How does the film get agitated during development?

 

When one develops still film at home, you must "agitate" the film by either shaking, stirring or inverting the container containing the film and the developer. The process is supposed to be crucial to ensure the film is constantly being exposed to fresh developer. Naturally, the jumbo processing machines must use a different method.

 

Does the processing machine used for movie film utilize some way of doing this? Or because the film strip is constantly moving through the developer, that itself provides constant re-exposure to fresh(er) developer?


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#2 Dirk DeJonghe

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Posted 22 May 2017 - 11:50 PM

There are submerged spray nozzles impinging fresh developer on the emulsion side every few seconds. There is one pump for heating, circulation and filtration of the developer and another powerful pump only for agitation. Movement of the film itself is not enough to insure streak-free processing.
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#3 Gregg MacPherson

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Posted 23 May 2017 - 02:49 AM

In the gap between stiil film development and continuous motion picture processors,  the lomo tank exists.  It just needs turning on the spindle with your fingers.  Similar I suppose to processing stills.  Years ago,  I had friends with a small continuous B&W processor which used aquarium pumps to circulate the solution continuously.  The basic ideas are brutally simple.  The professional labs will have more sophisticated methods with better measurement.


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#4 Robert Houllahan

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Posted 23 May 2017 - 11:57 PM

Yeah as Dirk said, there are large powerful pumps and a set of wands between the film loops in the tank racks to agitate / circulate the developer.

 

Our Photomec has two 3-phase motor pumps with 2" intakes and outlets.


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