Water spotting on film edges?

gezak22

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Howdy folks. Apologies in advance if I am posting on an age-old topic or in the wrong forum.

I am seeing some spots on the edge of some of my negatives. It is most obvious on one edge that goes along the length of the roll, and I frequently see it when shooting a bright featureless object (blue sky for example). It is possible that it is present in other situations as well and I just don't see it. I see this with multiple cameras (Hasselblad 6x6, Voigtlander 6x9) and multiple film stocks (Delta 400, Acros), so my next suspect was my plastic reel, thinking that the ledge of the reel was perhaps covering the negative. But I recently switched to a metal reel and I still see the same problem. Below is an example. I am now thinking that this might be an issue with the way I use LFN or the way I dry my negatives. Thoughts?

I use 7 drops of LFN in 1.5 L of distilled water as a final rinse (with plenty of other rinses before the final rinse, the penultimate rinse happens in filtered water). The film (on reel) is gently agitated for 30 seconds in the final rinse, and it then rests in this final rinse for ~2 minutes so all the bubbles that were generated during agitation disappear. I then pull the reel out of the bath and hang the negative vertically. I do not shake the reel (to remove as much water as possible from the negative), nor do I use a squeegee (or similar) once the roll is hanging. Drying happens in a warm/humid room while the next batch of water is being distilled.

Any thoughts on what I should try next? My best guess is that this is water spotting which suggests that I am not using enough Edwal LFN. But 7 drops in 1.5 L is already on the high end.?

 

koraks

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gezak22 said:
Thoughts?
Click to expand...

These low-density blobs are the result of air bubbles lodged underneath the top half of the reel, where they impede development. What usually helps is to slightly increase the developer volume so the bubbles get pushed out through the reel more readily as you rap the tank on the counter after agitating (which you should do, in case you don't).

The problem is unrelated to your wash, the use of a wetting agent or how you dry your film. It arises during development.
 

Doremus Scudder

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This is likely caused by foaming or air bubbles at the surface of the developer in the tank, which is also not quite full enough.

Make sure you are using enough developer to completely cover the reels and then some, but leave a bit of air space for proper agitation.

After agitating, rap the tank sharply on the countertop to dislodge air bells clinging to the film.

Keep your tanks clean. Wetting agent residue in the tank can cause foaming of the developer.

Hope this helps,

Doremus
 
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gezak22

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Aha, interesting. Yes, I always use at least 600 mL of solution in my 1 L tank. This covers one reel, and I also have a second reel in the tank so the bottom reel (the one with film) stays put. And yes, I give the tank a solid tap after inversion.

But the example above used 900 mL of water + 12 mL of developer, so it was plenty full with plenty of air for proper agitation, and I tapped the tank religiously.
 

George Collier

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I eliminated just about all developer surface level issues (for 35mm) by using a 2 reel tank, using 2 reels every time, whether 2 rolls or not, and pouring in exactly what it takes to cover the top edge of the top reel plus a few ml's for safety. I also place a spacer (cut from 2" pvc pipe) on top of the top reel, to keep the reels from moving up and down with agitation. The spacer is just the size to keep the reels from moving, but not too big to bind them. This is 455 - 460ml for my Nikkor reels and the 500ml Kinderman tank. I'm amazed at how many of these edge issues disappeared - bubble marks, and even surge effects. Agitation is an inverted twist, 4 times. First 4 minutes, agitation every 40 seconds, each minute afterwards. Developer is Rodinal 1:48.
 

Sirius Glass

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I tap my tanks by thumping if on a thick piece of hard rubber I got from a hobby shop.
 

Pieter12

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I used to get streaks from uneven development until I adopted a continuous rotation drum roller. Made all the difference in the world for me.
 

loccdor

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The problem of bubbles during development can be related to leftover wetting agent clinging to the reels from a previous development.

Some people clean the reels with a toothbrush thoroughly after development... some people do the wetting agent while the film is off the reels. What I do I just give the film 5-7 agitated prewashes before starting the development. It solved this problem for me, the same one you have. It also removes contaminants from the film so they won't go into your developer, if you're not doing one-shot development.
 

koraks

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250swb said:
If you don't invert the tank to agitate the developer you won't get bubbles
Click to expand...

That's not necessarily true; the bubbles can emerge when pouring the developer into the tank, especially if there's a significant residue of wetting agent.
I don't expect that in this particular case the twizzle stick is going to be much of an improvement; I think increasing the developer volume will help, although I'm a bit puzzled at the fact that OP is apparently already doing this and still has this issue. Also, note that back in the 1980s it was already demonstrated that the twizzle stick is likely not part of the answer when it comes to perfectly even development.
 

Sirius Glass

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250swb said:
If you don't invert the tank to agitate the developer you won't get bubbles so use the twiddle stick instead, and use more developer so if a bubble does want to form it's above the height of the reel.
Click to expand...

Just pouring in the chemicals alone can cause air bubbles which is why I thump the tank on a thick rubber pad several times after each addition of chemicals.
 
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gezak22

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Alright, I found another Simma roller and I'll give it another try. Assuming it resolves uneven developing issues, I should be able to adjust potential contrast issues by adjusting developing concentration/time.
 

250swb

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You say that as if I wasn't around in the 1980's (I finished my photography degree in 1978) and don't remember any 'proof' that the twizzle stick was a villain. Admittedly it was the first thing people lost, and general advice has always been to invert the tank, but that's not specific advice. General advice covers everything including extended development times when you'd want to invert the tank to re-mix exhausted developer so it's do-it-all advice, but for anything less than 15 minutes it's pointless and the twizzle stick removes any opportunity for surge streaks and bubbles. I also don't remember the 'problem' of the even larger and longer twizzle stick used in a deep tank equipped darkroom, and if you inverted one of those tanks you'd be in trouble.

Bubbles and surge streaks are common problems brought up on the forum, nearly all have similar causes based around inversion and sloshing the developer about. So if you've got a headache caused by streaks and bubbles it's a good idea to stop banging your head against the wall and perhaps wonder why you've been sold a little plastic tube? And if it's been lost or not provided swishing the developer around the tank is just as good.
 
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koraks

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In the post I linked to, I summarize an article with some comparative tests that @MattKing provided. It also featured a test with the twizzle stick (combined with regular agitation). It produced unevenness problems on 35mm; it can only be expected these would be exacerbated on 120 film because the image extends outward closer to the edges of the film.

Most of us who do inversion agitations tend to get away without too much head-banging or bubble problems. As long as I keep the liquid volume in my Paterson tank to just cover the reels & film, manual inversions do just fine - and in fact give the best (=seemingly perfect) evenness I've been able to achieve.

Regardless, bubbles are evidently the problem and there are a couple of ways to attack this; I think for OP there's a good number of avenues they can try to improve matters and then stick (twizzle or otherwise) with what works for them.
 

Pieter12

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Many brands of tanks—Jobo being the one that comes to mind—do not come it’s or have accommodation for swizzle sticks. Maybe they’re not so necessary after all.
 

MattKing

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It was actually @gorbas who originally shared the article with me.
I expect that one of the many poorly accounted for variables when it comes to the problem with bubbles in tanks is that water qualities are themselves variable. Those qualities include how much air is dissolved in water.
 

Pieter12

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Interestingly, no matter what agitation procedure I use, when I empty the tank into a pitcher, the developer always has a layer of bubbles on the surface.
 

Sirius Glass

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Pieter12 said:
Interestingly, no matter what agitation procedure I use, when I empty the tank into a pitcher, the developer always has a layer of bubbles on the surface.
Click to expand...

While PE advised against it, it sounds as though the water surface tension is too high. If so a little PhotoFlo could reduce or eliminate the bubbles.
 
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gezak22

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Well, I always use at least 12 mL of Rodinal per roll of 120 which I am told is sufficient, and if not, I would expect it to cause issues all over the place, not just at the edges. The shape of the defects also supports the hypothesis of bubbles.

I am almost finished characterizing the curves for Acros, FP4, and HP5 in a Simma Sine Wave roller, and I should have a first test roll done in a few weeks.
 
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