Air bubbles at edge of frames causing uneven development

GLS

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Can anyone help me with this problem?

I develop my own B&W 120 roll film in Paterson reels/tanks, and have started to see this issue with increasing regularity: on some frames I sometimes see these pockets of decreased negative density, which clearly look like they are caused by air bubbles preventing even development. See below for a particularly bad example:



That one was developed with Pyrocat-HD (hence the colour) using Sandy King's "minimal agitation" routine, but I have seen the issue with other developers and more routine agitation too, so I don't think it is an agitation or developer issue (entirely, at any rate).

Just for completeness, here is my current development procedure:

- Using Paterson System tank + reels, as mentioned before
- Pre-soak the film for 3-5 mins using water at the development temperature.
- 500 mL developer solution per 120 roll, developing with various times/agitation methods as appropriate for developer/film. After each agitation cycle I always give the tank 5 hard knocks to dislodge air bubbles.
- 1% citric acid solution (freshly made) for stop. 30 seconds agitation in this solution, dump, then rinse with fresh water before fixing.
- Ilford Rapid Fixer 1+4, typically for 5-7 mins.
- Ilford washing method using tap water, plus an additional wash with deionised water, then a final wash with 5% IPA in deionised water.
- Hang to dry (without using a squeegee).

As I said, I seem to be getting this problem with more regularity lately, although I have always occasionally experienced it. It is only ever really visible in the densest areas right at the edge of the frames. The only things I have recently changed are: I started to use a pre-soak; I switched to 500 mL of working solution per 120 roll (I used to use 600 mL); and I started to use the final IPA rinse.

I suspect the most likely cause is the pre-soaking step and/or the reduction in developer volume, but would welcome other suggestions. Are Paterson reels more prone to trapping air bubbles than other brands (although I don't see why they would be)?

Thanks in advance.
 

Ian Grant

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Add a couple of drops of wetting agent to the pre-soak or developer. No more than that or you'll cause foaming which is worse.



When I lived in Turkey I had issues, our water there is very hard, this cured the problem completely. No amount of agitation removed the air bubbles, it just moved them elsewhere I now add the wetting agent to my Pyrocat HD Part A when I mix from raw chemicals, most commercial developers have a small addition of surfactant.

Ian
 
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GLS

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Thanks for the suggestion Ian. I may well give that a go, although as you say I would be worried about the foaming making it worse. I used to use Ilfotol in DI water as a final rinse, but gave up on that due to it leaving residues on the film. I noticed even a few drops in 5-600 mL caused a lot of foaming when it was agitated.
 

Ian Grant

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I tested for foaming with plain water first, 3 drops of the wetting agent I use in 500ml was OK, but wetting agents do vary in concentration. You can always dilute some wetting agents and try drops of the diluted WA.

Ian
 

Michael W

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This has been discussed here before, although I don't recall the thread title. I have also had the same problem. I believe it is caused by foaming developer sitting at the top edge of the film. I believe you can eliminate it by having the dev volume higher than the top of the film, so with a standard Paterson tank use 600ml rather than 500. I recall that was the general consensus solution the previous time this was brought up. Of course Ian Grant's suggestion might well also work but I haven't tried that.
 
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GLS

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OK, thank you both for the suggestions. I did occasionally see this back when I used to use 600 mL of developer, but much less often. Also, as far as I recall I only saw it before in these situations (i.e. using 600 mL) when using Pyrocat-HD with minimal agitation, which presumably exacerbates the problem when it occurs.

Next roll I develop I'll try switching back to 600 mL volume and maybe add 1 drop of Ilfotol to the developer for good measure.
 

Andrew O'Neill

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Which film are you using? How do you agitate? I taught my students to use the figure 8 method of agitation... and never use a water pre-soak. We use HP5 and it's not recommended. We always make sure that there is 400ml solution in the Paterson tank.
 

MattKing

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Scrub your developing reels - an old toothbrush works well. If there is even the slightest amount of gelatin or other residue adhering to them, it can affect how even the development is.
 
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GLS

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Andrew O'Neill said:
Which film are you using? How do you agitate?
Click to expand...

The example I posted above is from T-Max 400, but I have seen it with various B&W films.

My agitation method is to use slow inversions whilst simultaneously rotating the tank along its axis, which creates a kind of figure of eight pattern.
 

Ian Grant

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Foaming looks quite different, that's typical air bells. I always us slightly more than the suggested volume with my tanks. I'd add that in the photo I posted that Paterson reel has no film loaded, it's harder still to remove air bells when there's a film present.

Part of the issue with mixing your own developers is it's rare to add a sequestering agent to counter the effects of hard water, typically Sodium Hexametaphosphate or Sodium Tripolyphosphate are used in a small quantity, the former is used more typically used in liquid developers and the later in powdered developers.

So a commercial developer would have a sequestering agent as well as a very small amount of wetting agent. In the case of Pyrocat HD there's no sequestering or wetting agent so having no sequestering agent while living in Turkey I added just wetting agent, and have done for over a decade

Ian
 
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GLS

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I think I'll do some experiments with the open-topped film tank and see if I get persistent bubbles clinging to the reel, as in the photo in the 2nd post. If so I can try adding Ilfotol a drop at a time and see at what point (if any) it stops...
 

Photo Engineer

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Foam is a large number of air bubbles. They are the same thing, but originate from a number of different and sometimes the same causes.

In either event, use of a sequestering agent is often called for, as is a good rap or two on the counter top when the tank is filled and during development. This dislodges the bubbles. Use of more solution is often the answer to many of these instances.

In effect, we have a list of possible solutions which may be used alone or in combination.

PE
 
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GLS

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The water in my area is only rated as "slightly hard", with a hardness clarke of 8.4.

I just did a simple test of pouring 500 mL of water into the tank (with an empty reel inside) via the usual funnel top, then performing one of my typical agitation cycles + tank knocking. On removing the funnel top and checking the reel, there were still one or two lingering bubbles clinging to it. I did find that adding 1-2 drops of Ilfotol to this volume could be tolerated without causing excessive or long-lived foam. However simply adding another 100 mL of water seemed to have the largest effect (500 mL really only just covers the reel), so I think I will try 600 mL of developer + 2 drops of Ilfotol next time and see how I get on.

I originally dropped my usual 600 mL developer volume down to 500 mL because I had been trying out SPUR's Dokuspeed SL-N (a very expensive developer) with some Copex Rapid, and the volume of part A concentrate supplied in the kit works out as a neat multiple of the amount to be used in making up 500 mL of working solution. I saw no trace of air bells then, so thought it would be safe to adopt this as a general practice (although I did use DI water to make up that working solution, as per SPUR's data sheet). But I digress...
 

Sirius Glass

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I have linoleum block that I thump the steel tank.
 

Ian Grant

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mshchem said:
Simple question. Is Pyro worth the trouble?
I've never fooled with it.
Click to expand...

Simple answer - Yes.

Longer answer - Definitely after 14 or 15 years of using Pyrocat HD. It's when I go back to older negatives I realise how easily Pyrocat negatives print, how highlights don't bock up. how well fast films push, the exquisite tonal range, the micro contrasts and over all sharpness. I switched from Rodinal and Xtol probably two of the best developers available (I'd qualify that by saying Rodinal and Tmax 100 or genuine Agfa Ap100/APX100), that doesn't mean there aren't other good developers, just those suited me.

Ian
 

Andrew O'Neill

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GLS said:
The example I posted above is from T-Max 400, but I have seen it with various B&W films.

My agitation method is to use slow inversions whilst simultaneously rotating the tank along its axis, which creates a kind of figure of eight pattern.
Click to expand...

Perhaps the inversions are generating too many bubbles?
 

Andrew O'Neill

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Ian Grant said:
Makes zero difference if there's no Wetting agent you can't resolve the issue. And such a tiny amount of wetting agent cures the issue instantly, it's a bit of a no brainer

Ian
Click to expand...

You haven't seen some of my students agitating, then. Some of them you'd swear they were making cocktails. Excessive agitation generates bubbles.
 

mshchem

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One more thing I have on my to do list. I've used XTOL for last 20 years. I will have try Pyrocat HD.
 

mshchem

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Try DiGel antacid, has simethicone, Dow anti foam. JUST KIDDING! Stay clear of Photo Flo. The LFN Edwal product is supposed to be low foaming.

I would suspect residual surfactant on the reels from prior sessions.
 

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Ian Grant said:
But they are also very much larger air bubbles by quite a large margin and they also spread deeper not right on the film spiral edge.

when I did my visual test it surprised me that the rap or two had almost no effect.

Ian
Click to expand...

When you have foam (or bubbles) created in the presence of a surfactant, rapping the tank has almost no effect.

PE
 

Ian Grant

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Photo Engineer said:
When you have foam (or bubbles) created in the presence of a surfactant, rapping the tank has almost no effect.

PE
Click to expand...

My practical experiments with just tap water showed rapping the tank has minimal effect. However foaming has a very different effect and the results look totally different, think of blowing soap bubbles, they are large, in a tank foaming is still much larger and effects will only be seen with poor/ minimal agitation but they can't be mistaken for air bells.

As the PP is using a developer with no sequestering agent or wetting agent foaming isn't the issue.

Ian
 
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