Archived posting to the Leica Users Group, 1998/09/06

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Subject: Re: [Leica] Invert or rotate
From: Dave Richards <>
Date: Sun, 06 Sep 1998 11:08:16 -0600

I've used Patterson tanks in the past (I use Jobo now) and the rotating
agitation method you cite.  At least I did for a while.  Then it occurred
to me that inverting the tank actually washes the developer over the film
and, in effect, remixes the stronger developer with the weaker portion that
has been in contact with the film, whereas simply rotating the reel
horizontally simple moves the weaker developer from one part of the film to
the other with out remixing it.  I never noticed a real difference using
either method, but since I couldn't find a flaw in my reasoning and
inverting the tank wasn't a bother, I continued to do so.

>I use Paterson tanks for developing 35 mm and 120/220 mm film.  Each of
>these tanks come with a device with which you can rotate the reels back
>and forth while the tank stays on the tabletop.  I use this rotating
>method instead of inverting the tank, one back and forth rotation
>substituting for one full (90 degrees and reverse)  inversion.  I find
>this method simpler and less messy since there's no possibility of
>spillage and I don't even have to use the tank cover.
>I would like to solicit other people's opinions about this method.
>There may be advantages/disadvantages to either method that I am not
>aware of.