Novice development question: dark 'blotches' along the length of film

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hinius

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Hi,

I've been getting a strange (to me) problem, quite consistently, when developing b&w film. Alongst the film strip (lengthwise, running along it), usually at the start or the end of the roll, I sometimes get a large dark 'blotch' running from the sprocket holes that 'seeps' into the picture.

I'm not sure I'm describing this very well, but think of when you watch a widescreen DVD on your regular TV, how you get black and white letterboxes at the top and bottom of the screen. Or if you want another analogy, load up a picture in Photoshop and paint using the black airbrush tool along one horizontal edge. I'll get one of those black letterboxes (naturally, the darkness 'blotch' is very inconsistent and not completely black, just a lot darker than the rest of the image). This naturally ruins the picture (so far I've been lucky and have only had crap frames ruined).

I develop using Paterson equipment, using plastic reels with Tri-x and Diafine. I develop two reels to the tank. I've switched a few reels around so I don't think it's reel related. What I have noticed:

- Whenever I develop two reels to the tank, only one reel shows this symptom (I have not yet determined if this is a problem with the top or bottom reel)

- The entire film is never ruined, just usually (but not always) the start and end of the film.

- Only one of side of the film is blackened/darkened.

So it can't be my technique, because if it were I would consistently ruin two rolls of film per development cycle. Quite often both rolls come out absolutely fine. Sometimes one roll is ok, but never are both rolls ruined.

Does anyone have any ideas what this could be? I'm still a relative novice when it comes to development so no question is too stupid for me.

Thanks!
 
Have you been using the same camera to shoot all the films with these symptoms ? Maybe its a weird light leak ? Are you sure the film is fixed long enough otherwise... cant really see why that would make that kind of shape, but you will get blotches if its not fixed long enough... Strange problem :-/
 
Are you bulk loading? Do you have a leaky canister that you keep re-using? If you're using a bulk loader, could it be an extremely slow pinhole light leak that only shows up when the film is sitting stationary in the gate, i.e. when you're cutting the film and preparing the next canister?

Or, could it be that the development tank is leaking light, fogging the roll on top? Perhaps leaking from the core of the funnel, affecting just the leader of the film in the center of the top reel?

This sounds like a pretty elusive one. :(
 
Stephan said:
Have you been using the same camera to shoot all the films with these symptoms ? Maybe its a weird light leak ? Are you sure the film is fixed long enough otherwise... cant really see why that would make that kind of shape, but you will get blotches if its not fixed long enough... Strange problem :-/
Click to expand...

Thanks for reply... it's definitely a strange one. I am using the same camera (a pretty minty Hexar RF). I have considered the light leak option, but I have gotten my film processed by a lab and I haven't seen any of these problems. And if it is a light leak it would be extremely inconsistent light leak.

I fix for at least 5 minutes with inversions at every minute mark for about 10 seconds... fixer is replenished every 10 films.
 
Try a roll of colour film (neg or chrome) and have it developed commercially. That will point to either the camera (if it's still there) or the home developing (if it's not) being the problem.
 
tetrisattack said:
Are you bulk loading? Do you have a leaky canister that you keep re-using? If you're using a bulk loader, could it be an extremely slow pinhole light leak that only shows up when the film is sitting stationary in the gate, i.e. when you're cutting the film and preparing the next canister?

Or, could it be that the development tank is leaking light, fogging the roll on top? Perhaps leaking from the core of the funnel, affecting just the leader of the film in the center of the top reel?

This sounds like a pretty elusive one. :(
Click to expand...

Once again, thanks for your suggestions. I'm not bulk loading... but maybe it is a tank issue?

One very silly question; I have a Paterson super system tank that comes with a little spinning rod thingie that slots into the core of the funnel that you twist around to invert the film. Sometimes when I develop I neglect to leave the spinner when I change liquids. I'm wondering if I have to leave the spinning rod thingie (very technical term) in place whilst I develop?

Or perhaps I might buy another tank and see if that fixes the problem... but once again, getting me thinking!
 
hinius said:
Thanks for reply... it's definitely a strange one. I am using the same camera (a pretty minty Hexar RF). I have considered the light leak option, but I have gotten my film processed by a lab and I haven't seen any of these problems. And if it is a light leak it would be extremely inconsistent light leak.

I fix for at least 5 minutes with inversions at every minute mark for about 10 seconds... fixer is replenished every 10 films.
Click to expand...

Hmmm.... I'd say your not fixing long enough. I tend to fat least 10 minutes, up to 15 depending on what the film looks like. Do your BW negs come out completely transparent where they should ? No weird pink or purpelish coloration ? 5 minutes doesnt sound long enough to me, try fixing for 5 minutes, then open the canister (its safe by then), have a look at the film, then put it back in and fix another 5 minutes and see if it looks any better :)
 
With out seeing a sample of your problem I'm going to second tertrisattack's guess on the funnel portion of your developing tank. Are your using a spindle that is long enough to reach the lid on your developing tank?

Wayne
 
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hinius said:
Once again, thanks for your suggestions. I'm not bulk loading... but maybe it is a tank issue?

One very silly question; I have a Paterson super system tank that comes with a little spinning rod thingie that slots into the core of the funnel that you twist around to invert the film. Sometimes when I develop I neglect to leave the spinner when I change liquids. I'm wondering if I have to leave the spinning rod thingie (very technical term) in place whilst I develop?

Or perhaps I might buy another tank and see if that fixes the problem... but once again, getting me thinking!
Click to expand...

Unless theres a hole in the tank the little spinning thingy doesnt make any difference, you dont need it to seal the tank. I actually never use that thing 'cos I can never find it, I just shake the tank and its never been a problem :)
 
Hey how about this: are you using a 2 roll or 3 roll tank ? If your using a 3 roll tank and you havent locked the 2 spindles down on the central bar thingy with a clip when you invert the tank the top roll might be moving to far up and not get enough exposure to the soup :)
 
Stephan said:
Hey how about this: are you using a 2 roll or 3 roll tank ? If your using a 3 roll tank and you havent locked the 2 spindles down on the central bar thingy with a clip when you invert the tank the top roll might be moving to far up and not get enough exposure to the soup :)
Click to expand...

Hey Stephan,

I'm using a 2 roll tank... I think I might try one or more of the following: buy a new tank to confirm it isn't a tank problem, fix for 10 minutes (the instructions for Ilford Rapid Fixer say 3-5, but extra fixing can't hurt right?) and get a roll processed by a lab. Surely one of these will result in more clues!

Thanks!
 
hinius said:
Hey Stephan,

I'm using a 2 roll tank... I think I might try one or more of the following: buy a new tank to confirm it isn't a tank problem, fix for 10 minutes (the instructions for Ilford Rapid Fixer say 3-5, but extra fixing can't hurt right?) and get a roll processed by a lab. Surely one of these will result in more clues!

Thanks!
Click to expand...


I hope so 'cos I'm out of ideas :D And all this belgium beer that's been disappearing from my fridge should have given me some extra inspiration at this point :) And by the way, over fixing way to much will eventually make the emulsion float off, but only if you forget the film in the fixer overnight or something :D

Dont forget to tell us how it turns out :)
 
Ilford fixer has two dilutions. 1 + 4 for film and 'high' speed print fixing and another 1 + 9 for normal print fixing. Is it possible that the dilution is 1+9, it's easily done. :confused:

I also use Ilford Rapid fixer and it's fine in the stated times.

Just a thought, but do you agitate the fim in the fixer? using that twirly twiddle stick. You should do this at least for the first ten seconds or so (plus a bump on the sink to dislodge bubbles) or invert the tank to ensure that the fixer has reached all the areas of the film.

The techy bit follows, feel free to yawn: :eek:

Now given that you fill the tank from the middle, the solution will creep to the outside of the tank and not move whereas the inner part of the spiral will have solution rushing around it as the tank fills, so in theory according the very outside of the film in the spiral will be fixed less than the inner if no agitation is performed.

Just a thought. :rolleyes:
 
Hey, just wanted to point out that if fixing is the problem, the blotches won't be black -- they'll be opaque, or yellow. Black means that the film is exposed before or during development.
 
Just a thought, but maybe you don't have enough developer in there. If the chemical level is right at the top edge of the film, agitating with the spinning rod thingie (aka twirly twiddle stick) might be sploshing the developer around the edges without ever getting a good coat.
 
TPPhotog said:
The part that's confusing me is that they are only at the start or end of a roll and not the length :(
Click to expand...

That's why I'm wondering if it's a light leak at the center column of the tank. A circle of light would shine directly down onto the top of the innermost spiral, affecting only the part of the film closest to the core - the film leader or trailer, depending on which end of the film was fed into the spiral first.

That's pretty far fetched, though. I just looked at my patterson tank (I never use it, in favor of stainless steel) and the funnel nozzle is designed to rest inside the central column, so there would have to be some sort of gap between the two, maybe mismatched parts or something.

How frustrating! :bang: Try sending one off commercially, as was suggested earlier. That'll at least rule out the camera.

If not the camera, the next step would be to establish which roll, top or bottom, is the affected one. If it's the top, then you've got some sort of light leak in the tank, and troubleshooting it would probably be more difficult than just buying a new one.
 
Noting that you already said the problem didn't appear on a lab-processed C41 roll, it seems like the film edge is being exposed. By dark, do you mean the negative is dark, as opposed to the positive print/scan? Does the dark blotch go all the way to the cut edge of the film, or does it stop at the sprocket holes? The plastic reel would probably shade the very edge a little and give a thin less-exposed edge if the tank is leaking light. A chemistry issue would probably go all the way to the edge.

You could investigate on a cheap roll of unexposed color film. It'll make the Diafine uglier than it already is, but it won't damage anything. You could snip the upper corner off the end of the film that's on the outside of the reel (nail clippers won't take your finger with it). That way you'd know which edge is being affected.

In any case, good luck and please report your findings!
 
I use a Patterson tank, too and had this same problem. I went through all the usual speculation, and this problem seemed to happen when the film hung up on the reel, while it was being loaded up. I found that the film hung up on the reel, when the canister was not held in front of the two little guides where the film enters the reel. I would usually be holding the canister above the little guides causing the film to go into the reel at a sharp angle.

The easiest way to tell if the reel is loading up properly is that the film should be coming out of the canister effortlessly. If there is even the slightest hint of any resistance, than you probably need to rotate the reel until the film is going straight into the little guides instead of at an angle.

Hope that helps,

Richie
 
Ive had a similar problem once with 120 film. I had left the black plastic spool (that the reel goes onto) out of the tank. I didn't realise that this forms part of the light barrier. Is it possibel you've done this. Not the black twistie thinggie you use for agitation, the other black thinggie the spool slides onto.

Cheers
 
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