Thanks to John, Scott & Charlie for your help in answering my airbell problem. Pre-rinsing plus tapping before beginning developer agitation seems to have eliminated the airbells I was getting. I now have a worse problem...MAJOR streaking of the negs, never experienced before. The streaks are parallel to the short axis of the film, mostly print as lighter [denser] streaks but also can have a darker [thinner] component to them as well. I know they are caused by the little triangular teeth which hold each sheet in its groove in the Jobo reel, as streaks and teeth line up all too perfectly. But why are they appearing now? Is my great new airbell-eliminating pre-rinse swelling the emulsion and making it too sensitive to the developer before I begin initial agitation? As this is occurring on 4 - 6 sheets of film per tank [thus bringing me to a complete halt until I sort it out] and since due to finances I'm stuck with hand processing in a tank for now, I would be very grateful for any clues. thanks in advance rebecca

-- rebecca (rebecca@antart.com.au), March 10, 2002

Answers

I develop all my 4x5 sheets in a Jobo tank (manual inversion) and prerinse many of them. Never had a streak problem. Maybe you are using a too strong developer solution (or too warm ???). Don't agitate too vigourosly, take it easy. When you inverse the tank (while agitating) try to turn it around itself at the same time (an ancient Chinese technique of agitating developing tanks).

-- George Papantoniou (papanton@hol.gr), March 10, 2002.

As to why you are getting streaks now, its because the Jobo tanks are not made to be used the way you're using them. When you have the single tank full of chemistry you are not able to get even agitation. You're probaly not getting much exchange no matter how you agitate. The single tank is too full when the film is covered completely in developer. Its really made to be used on the revolving processor with much less developer. The extra room in a larger tank will let you get good, even agitation by hand.

So, what you need is another tank. The Jobo 2551 is made to hold two 4X5 film reels. Buy one of these. Fill it with developer to a level slightly higher than the height of a single 4X5 reel. Then with the lights off transfer your loaded reel (you already loaded it and placed it in a capped single tank) from your single tank into the 2551, clip on the top and start initial agitation. A continous gentle swirling or rolling will do. Or if you can keep the lights off you could raise and lower the reel, then clip the top on and work in light for the balance of the time.

A single tank is not deep enough to allow you to cover all the film even when filled to overflowing with the top off so you can't prefill a single and get nearly instant coverage/wetting of the film. Pouring the large quantity of developer needed to fill the tank takes too long and is one cause of your problems. Thats another reason why you should buy the double tank and pre-fill it. When you place the film in the pre-filled tank it is instantly covered/wet by the developer. You can continue to pre-soak your film if you like before transfer to the developer filled double tank. You might want to use another reel on top of the loaded one to be sure it stays down in the developer, or make a spacer to do this.

I'd agitate the double tank by rolling it one or two gentle revolutions on its side each 30-60 seconds, then standing it upright. Be gentle! Too vigourous agitation might dislodge the film from the reel. A liter of chemistry sloshing around in a 2 liter tank can have a lot of force against the sheets of film.

Alternately, you could turn off the lights each minute and lift the film out of the developer then set it back down. Or leave the lights off and raise and lower the film as needed. Have your stop and fix in containers ready to pour in the tank.

Pouring all your chemicals with the cap off, in the dark would be great! (although probably not necessary, it might be better) I'd stop with plain water only and roll the tank continously for one minute, drain, lights off, cap off, then pour in the fix, cap and roll for first minute, roll occaisionally through the fixxing time.

-- Henry Ambrose (henry@henryambrose.com), March 10, 2002.

thank you henry and george for your replies. I've always done all of what you do, George [except I always thought it was ancient Egyptian method of agitating, not Chinese]. Your points Henry about the problems of using manual agitation and a tank overfull of chemicals are valid, and I will try a larger tank when I can afford it and the different agitation methods and tank filling you suggest. I'm just baffled about the sudden appearance of these streaks - logically they should have been present all along if my method is the problem.

-- Rebecca (rebecca@antart.com.au), March 11, 2002.

It sounds like Bromide Drag caused by to much agitation. If you can, slow the agitation down and that should help. This is VERY common when using Technical Pan with Technidol. Cheers

-- Scott Walton (walton@ll.mit.edu), March 11, 2002.

Henry, I have been using the large tank in the beginning and now I use the small one (single reel) but never encountered the problems you are mentioning. This Tank I have is not made only for rotary processing... (I don't remember the specific type's product number by heart, I can check it out for you if you want, though).

-- George Papantoniou (papanton@hol.gr), March 11, 2002.

The single tank I refer to is a 2523. It is made only for rotary processing. If you have this tank, notice that when the lid is off and a reel with 4X5 film is inserted, the top edge of the film is not in the developer. Which is not so bad because you use it with the lid on. But what happens sometimes in perhaps marginal situations is that pouring the developer through the top takes too long. Pouring in 250ml is pretty quick, but to fill the 2523 tank takes 4 times as much developer and 4 times as long! This is why I say to use the larger tank, pre-filled with developer - then drop in the film. You get instant wetting of the film. If you try this with the single tank the top edge of the film is not wet until you cap the tank and then fill it a bit more. My comment is not that you can't do it, its that you might be having problems because of the technique used. Jobo suggests not using any of these tanks for hand inversion with 4X5 film. But I think using the larger tank and good technique you can get by with it. I know that when I'm too lazy to set up my processor and simply fill the single tank I will get poor results, so I don't do that anymore. If I use the double tank and the procedure I posted above manual results are fine and consistent.

-- Henry Ambrose (henry@henryambrose.com), March 11, 2002.