how to prevent bromide drag

[ChrisLivsey]

There is no unity

- in almost all of the variables in developing film.

Developer BEFORE fixer is I believe non contentious, but then there are the "all in one" devotees !

 

[Mike Fish]

There is no unity regarding the right agitation...

After rereading the thread, it seems to me while there isn't complete "unity regarding right agitation," there does seem to be consensus that slow & gentle are WRONG agitation.

I start to invert the tank for 10 seconds

When I read this I wasn't sure if you meant you turned the tank over ONCE and left it there for 10 seconds, or if you inverted it multiple times during the 10 seconds. Once would be a problem, I would think.

-mike

 

[tho60]

After rereading the thread, it seems to me while there isn't complete "unity regarding right agitation," there does seem to be consensus that slow & gentle are WRONG agitation.



When I read this I wasn't sure if you meant you turned the tank over ONCE and left it there for 10 seconds, or if you inverted it multiple times during the 10 seconds. Once would be a problem, I would think.

-mike

I do continous agitation (about 5-8) during the 10 seconds, yet I have got ruined negs.

 

[rpavich]

Dear Thomas,

Yes, that's a bar steward: trying to be too slow and careful. Sounds even more like inadequate agitation. Swirl the tank before you lift it; invert; swirl at the end of the inversion. Aim for at least 3 inversions.

To help with leaks, cut a ring from a motor car inner tube -- go to a tyre/tire shop for a second hand/punctured one, explaining what it's for -- and use that to seal the top to the bottom.

Alternatively, get a better tank. Where are you?

Cheers,

R.

Roger, when you say "aim for at least 3 inversions" do you mean:

1) a slow continuous turn that takes 3 seconds to perform

Or

2) a fast flip over followed by a pause before the next flip over in which the flip + pause takes 3 seconds to perform.

Hope thats clear enough.

I have been agitating very vigorously and very fast in an effort to combat streaking but I tend to get grainy negatives. I just dont know how gentle is gentle.

 

[sevo]

Roger, when you say "aim for at least 3 inversions" do you mean:

1) a slow continuous turn that takes 3 seconds to perform

Or

2) a fast flip over followed by a pause before the next flip over in which the flip + pause takes 3 seconds to perform.

Go for 2 - a turn in three seconds is slow enough that it may leave pockets of air or stationary chemistry. AND it is surprisingly hard to maintain a steady pace at such a low speed - there is a lower limit to the rhythms humans can perform which also affects repetitive tasks like inverting a tank...

"As fast and hard as possible" obviously has limits in that you do not want to break the tank, pop the lid, spill any liquids, displace the reels or shake the film from the reels - but you want to be as vigorous as you can without causing damage.

 

[esearing]

Are you using one reel in a two reel tank? if so, put the empty reel on top.

 

[Fixcinater]

I believe by testing with the Paterson you've eliminated this possibility but one thing came to mind. I've chased down "development" problems that ended up being light leaked bulk film. What I thought was bromide drag from the sprocket holes was where light had penetrated. The large extent of the imaging surface was safe and usable, but obviously one edge had been exposed.

I got the film (in a bulk loader) as part of a darkroom lot, so I didn't know the history.

 

[Roger Hicks]

Roger, when you say "aim for at least 3 inversions" do you mean:

1) a slow continuous turn that takes 3 seconds to perform

Or

2) a fast flip over followed by a pause before the next flip over in which the flip + pause takes 3 seconds to perform.

Hope thats clear enough.

I have been agitating very vigorously and very fast in an effort to combat streaking but I tend to get grainy negatives. I just dont know how gentle is gentle.

Continuously for 10 seconds with at least 3 complete inversions-cum-twists. I normally do 5. I rarely disagree with Sevo but on this occasion I do. Try it with a reel in a clear jam-jar if you want to see why. Also, consistency is one thing, but trying to maintain the exact kipprhythmus to the nearest fraction of a second borders on the obsessive.

I also said at least three; three is where you might conceivably start to see bromide drag but at that I'd be surprised. I cannot see how more or faster inversions avoid "pockets of air or stationary chemistry".

Cheers,

R.

 

[tho60]

I have made an experiment. I did not any inversions, but I turned the tank left to make the reel axis horizontal and I rotated it for 10 seconds every minute. In the rest of the developing time the tank was in normal position. This method worked flawlessly.

 

[sevo]

I also said at least three; three is where you might conceivably start to see bromide drag but at that I'd be surprised. I cannot see how more or faster inversions avoid "pockets of air or stationary chemistry".

It takes some force to push air bubbles through the small slits especially on plastics reels. I've once had a assistant who did real five second inversions, moving like a Tai Chi master in slow motion - he indeed managed to create bubble patterned underdeveloped strips at the reel tops that way. Arguably this is less a matter of the agitation, but of the missing final push in such a obsessively gentle pattern - if he had banged the tank on the table when he set it down, that would already have dealt with that issue.