Some of the 120 format films I've developed (12) since my October 7 posting demonstrate this issue although others do not. Um.. I've got another film to develop this afternoon, so I'll try timeUnit's agitation suggestion.
It takes a bit of practice to get it totally right. Start with one film in the tank. As you get better, dev. two at a time etc. I seldom need to do more than two.
To get even more random "sloshing", which can be needed when deving two or three rolls at once, try varying the tilting of the tank: right, left, "away" and "towards" yourself. Don't be afraid to make the agitation a bit forceful.
It takes a bit of practice to get it totally right. Start with one film in the tank. As you get better, dev. two at a time etc. I seldom need to do more than two.
To get even more random "sloshing", which can be needed when deving two or three rolls at once, try varying the tilting of the tank: right, left, "away" and "towards" yourself. Don't be afraid to make the agitation a bit forceful.
Me too! That's the strange thing! I thought I had it all down, and suddenly I got these low density patches. I think it was due to me becoming "comfortable" or lazy when processing, and agitating with a too consistent pattern. I checked the developer, fixer, wetting agent, washed the reels like crazy etc. One person on photo.net recommended the new agitation pattern, and soon the problems were gone.
I have had the same problem with Airbubbles only by 120 Film and Patterson Tank for many weeks. I search the whole Internet and test all the proposals (avoid wetting agent ...), nothing help.
Now i have this bubbles very rarely and little since I change my initial agitation to 60 seconds gentle but permanent and one gentle agitation every 30 seconds. I think the problem outcome in the first time of the process and the 60 seconds of movement will prevent this.