I have spend a lot of time thinking about the source of the problem and I too have come to the conclusion that the tank has not been filled enough and that bands on the film are a result of insufficient chemical volume needed to properly cover the film.
A new hope…
So after trying all possible variations of development method and agitation pattern possible I finally had twice usable negatives again. But they are not perfectly even and streaks can be perceived on some views. Mainly because I am shooting a zone VI white board, but it will probably not be discernable on a textured surface. So at least I know I am on the right track. Here’s what changed that made a difference :
- Using more chemical. 500ml instead of 450ml in steel tank (haven't tried this on the Paterson tank yet). This change alone did not do anything and maybe is not needed but I suspect it was part of the problem. Although my reels were always well covered before, I think there was too much empty space in the tank. This was probably allowing part of the film to be out of chemistry during inversions. This is a wild guess since using a Paterson tank with the twizzle stick only and no inversion, just rotations of the stick, did bring some streaks too, but more in the center of the frame.
- Most importantly and this is the game changer : constant agitation for the first minute and not just 30s. I tried everything and nothing else worked until I implemented this. Then it’s 5 inversions every 30s.
I am open to more suggestion to get more even development as this is far from perfect.
I would also be curious to know how much developer do you all use with Paterson tanks per 120 roll. In 1 roll tank and 3 rolls tank.
Prewash did not do anything during any of the test, but I am thinking of trying it now again to see if I can get a more even development. Although film manufacturer recommend against it for a good reason probably.
It is completely mind blowing to me that this 30s more of initial agitation has such a dramatic effect. Even more so that I processed hundreds and hundreds of films with just an initial 30s agitation for years with no issues… Should also add that the lab guy whom I gave some films to test told me that he uses the Ilford recommended method of only 4 inversions at first then 4 inversions every minutes after that. He uses Paterson tanks and always avoid being much shorter than 10 minutes. Trying this gave me the worse results at 8 minutes development time. Go figure... someone probably sliced a chicken throat on a picture of me or something...
This brings me to the conclusion that more agitation is the best course to achieve even development considering my current karma, although probably not in force but in quantity. So changing to a Jobo rotary system probably makes sense. They have little rollers to allows manual rotation which makes the whole system quite reasonable. The question beeing which one to choose for best even development the 1500 or the 2500 system ? And do they both work well with the hewes reels (the ones with the large center for Jobo) ?