From: Carl Weese (cweese@earthlink.net)
Date: 07/21/01-07:21:35 AM Z
Sandy (if you're receiving)
I've been thinking about the print drum streak problem with staining
formulas. I've gotten excellent negs without streaks, but also enough with
streaks to avoid the technique. Tray development works fine anyhow, but for
those who have good reasons to prefer rotary processing...
You mentioned not using an after-soak. How do you wash--in the drum or out
and in a tray or washer? What I'm wondering is whether the streaking I've
seen may be *only* in the stain, not the development, and so occured during
after-soak or wash. That would mean that drum rib streaks might not happen
as long as the film is removed from the drum after the fix and given any
further treatments in a tray. I'm much too busy with current work to run a
test on this but experience of list members might hint at an answer. BTW,
there's a completely different bromide drag problem with regular
non-staining developers. D-76 (ID-11 should be the same) is the only
standard developer I've seen that doesn't cause bromide drag streaking when
processing large film sheets in print drums.---Carl
--
web site with picture galleries
and workshop information at:
http://home.earthlink.net/~cweese/
----------
>From: Sandy King <sanking@hubcap.clemson.edu>
>To: alt-photo-process-l@sask.usask.ca
>Subject: bromide drag
>Date: Fri, Jul 20, 2001, 10:02 AM
>
> My understanding is that the Jobo rotation is such that it imparts
> not only a horizontal rotation to the developing tubes but that the
> tubes also oscillate on a vertical axis enough to eliminate the
> effects of bromide drag. So, in short I think you have nothing to
> worry about in this regards.
>
> As film develops bromide is released from the emulsion. If the
> rotation of agitation is only in one direction ( or around a central
> axis) the excess bromide produced locally will produce uneven
> development, usually streaks of greater density with rotation
> processing, around this area. Vigorous agitation breaks up the local
> concentration of bromide and distributes it over the entire surface
> of the film.
>
>
>
> Sandy King
>
>
>
>
>> >Sandy King wrote:
>>
>>>Also, when developing film on motor bases like the >Beseler or
>>>Unicolor bases you should remove the tube >from the motor every
>>>couple of minutes and give it >about 10-15 seconds of up and down
>>>agitation, >otherwise the constant agitation fore and aft
>>>will >cause bromide drag.
>>
>>Sandy,
>>
>>Perhaps this has been discussed earlier. Can you explain what
>>bromide drag is? I use a Jobo CPP-2 which rotates in one direction
>>about 1 and a half turns, then stops and rotates in the other
>>direction about 1 and a half turns and repeats the cycle. Would
>>this action help to eliminate bromide drag? I don't think I have
>>ever had a problem with a negative that would have been
>>related to something like bromide drag. But I would like to
>>understand the issue better.
>>
>>Jim
>
>
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