Air Bells...Again!

[Onlyme]

I thought I'd seen the last of air bells, but they've returned and with a vengeance!

I was developing two rolls of Pan F 120 in my normal developer (PyroCat HD with extreme minimal agitation), both in the same Paterson Tank.

I had taken two special precautions against air bells, which for scores of films across several months seemed to have banished the problem. Firstly I gave the films a water pre bath. And secondly I overfilled the Paterson Tanks, using 1200mm of chemistry versus the 1000mm recommended. I also rapped the tanks firmly on the bench three times after each agitation cycle.

What's especially puzzling with this occurrence is that there are air bells on the upper edge of both the top and bottom film in the tank. I'd always thought that the bottom film in a two film tank was virtually immune from air bells as it is so deeply submerged in the chemistry. Apparently not!

Luckily none of the affected negatives was particularly important, but I'd really like to explore a more resilient development methodology to minimise the risk to a more prized neg in the future. So any suggestions of further steps I might take?

Here's the first neg which was sat at the bottom of the tank. It was a test roll for a new Imagon 250mm lens which I was using on a 6x12 back on a 5x4 camera. Look in the top left hand corner.



And here's a close up of the air bells (it also shows that coverage on a 250mm Rodenstock Imagon is looking a bit stretched at the outer corner of a 6x12 neg, but that's a different story!),



Next is a frame from the roll of 6x6 film that sat above the Imagon test roll in the development tank, again the problem is actually located in what was the top edge in the tank (although here it's been rotated so the problem appears on the side of the neg)



And here's a close-up showing the air bells in gory detail!



Any additional anti-air bell suggestions (beyond my current regime of rapping, pre bath, and additional chemistry) gratefully received!

 

[Glenn]

My dad always used to swear by a single drop of detergent in the prewash, agitating the film in the prewash and then tapping the tank before emptying and adding the developer. In other words, the film was fully wet before starting the development phase.

 

[Helen Summers]

That’s how I did it before I got lazy and went digital.

 

[Bill Martindale]

Do you do the final rinse with wetting agent in the tank on the reel? I had a similar problem a few years ago. Eventually, after some discussion with others on the Film and Darkroom User site, it was concluded that it was residue of wetting agent on the reel forming bubbles during development which were trapped in the grooves in the spiral. I now do the final wetting agent rinse in a separate jug. I suggest giving the reels a really good clean to remove all traces of the wetting agent residue. Just giving them a quick rinse after use does not always remove all traces of the wetting agent.

 

[Alan Clark]

Do you do the final rinse with wetting agent in the tank on the reel? I had a similar problem a few years ago. Eventually, after some discussion with others on the Film and Darkroom User site, it was concluded that it was residue of wetting agent on the reel forming bubbles during development which were trapped in the grooves in the spiral. I now do the final wetting agent rinse in a separate jug. I suggest giving the reels a really good clean to remove all traces of the wetting agent residue. Just giving them a quick rinse after use does not always remove all traces of the wetting agent.

I agree. I had problems from time to time, which stopped when I banned wetting agent from my tanks.

 

[John King]

Are you certain these are air bells? It is a long time since I had them but they were not like those on your images. They are blurred and out of focus and if they attached themselves to the film at least the edges would be sharp which is what happened to me

They used to crop up occasionally when I lived in West Sussex but moved back up to Durham in 2001 and since then there has never been a problem. Residue wetting agent can be a problem which a head *scratching problem. However I always give a final rinse to films both colour and B&W which allows the film to dry both streak free and flat.'

Every so often I pop all of my tanks, measures, and reels into the dishwasher which makes them very clean and also even removes small slight staining from colour chemicals. You can get the same effect by soaking the reels overnight in a very weak dilution of household bleach then rinse them off under a tap. I know It sounds awful, but it works well for me.

Household bleach is a good servant but you have to be careful. I also use it in my developing trays which stain when used with B&W and my nova processor will get cleaned every 12 months or so with 1 50/50 mix of water and Domestos. It cleans far better than the commercial cleaners sold to do the same job (and it is a lot cheaper too.) It still needs for the sections to be scrubbed with a slim bottle brush but the tar just falls away

 

[Alan Clark]

You say you put 1200mls of developer into the double tank. Maybe this is too much. I put 1020mls into a Paterson tank with 2 rolls of 120 in it. This nicely covers the top reel, and leaves an air space so the developer has somewhere to go when the tank is inverted. I think this is important.
And, sorry but I have to say it, I wouldn't be messing around with extreme minimal agitation. I invert the tank once every 30 seconds. I develop 120 film in ID11 at a dilution of 1+2 and get really sharp results.

 

[Onlyme]

Thank you all, some useful replies.

I looked into the question of Paterson Tanks being dishwasher safe, and unfortunately Paterson say they're NOT. The tank is polystyrene and the reels are acetal and neither material tolerates high temperatures. However, this technique clearly works for you, so how to square that circle? At a guess maybe it's that different dishwashers run at different temperatures, and some are cool enough not to cause damage? Maybe I'm just not feeling lucky, but I'm inclined to try other options first!

Filling the tank with slightly less chemistry is interesting, however the best research I've seen into this comes from George Post. He advocated slightly less chemistry for better agitation, but he also concluded that the bottom reel in a two reel tank is pretty much bullet proof. Given that he was patently wrong about that in this case, can I trust his other recommendations!

I'll be honest and say I'm sceptical about Photoflo in the pre-wash. I suspect Photoflo (or any other wetting agent) promotes foaming, I don't know for sure but I strongly suspect foaming is at the root of the problem?

One suggestion I expected but which no one has put forward is to switch to metal tanks and reels. I use both plastic and metal tanks, and I've never experienced air bells in metal tanks. But maybe that was just co-incidental? If anyone knows of any more rigorous research into the air bell resistance of metal tanks I'd appreciate a link? I get the attraction of metal tanks, but I find filling and draining can be a bit too slow, which is why I've not gone over to them exclusively.

Once again, thanks for the responses. Much appreciated.

 

[John King]

Thank you all, some useful replies.

I looked into the question of Paterson Tanks being dishwasher safe, and unfortunately Paterson say they're NOT. The tank is polystyrene and the reels are acetal and neither material tolerates high temperatures. However, this technique clearly works for you, so how to square that circle? At a guess maybe it's that different dishwashers run at different temperatures, and some are cool enough not to cause damage? Maybe I'm just not feeling lucky, but I'm inclined to try other options first!



Once again, thanks for the responses. Much appreciated.

Referring to your1st paragraph, you can always turn the temp down or even use the 'Eco cycle' it takes longer to complete, but the temp on my dishwasher on 'Eco' is only 40C which is only a little above the temp used for colour film processing (38c} I also use anormal washer tab, the cheaper ones still work for this method.

Make sure you split down the reels and take of the caps off the top. For what it is worth I use JOBO which are also polystyrene with no ill effects. Perhaps Paterson are just being over cautious.

 

[Onlyme]

Referring to your1st paragraph, you can always turn the temp down or even use the 'Eco cycle' it takes longer to complete, but the temp on my dishwasher on 'Eco' is only 40C which is only a little above the temp used for colour film processing (38c} I also use anormal washer tab, the cheaper ones still work for this method.

Make sure you split down the reels and take of the caps off the top. For what it is worth I use JOBO which are also polystyrene with no ill effects. Perhaps Paterson are just being over cautious.

Excellent points.