Minimum volume for sheet film processing in Jobo CPP-2

[Pasto]

I develop 4x5 B&W negatives in a CPP-2 processor using a 2521 tank (I think) and one 2509N reel. The tank holds one reel, and the reel holds a maximum of 6 sheets of film. I typically develop 4 sheets of film simultaneously in 300ml of solution (XTol 1:1). Recently, I’ve been developing sheets individually with the same tank and reel. The problem is that the tank has a minimum recommended volume of 270 ml, so that I use a lot more XTol than needed. I assume that the 270ml minimum recommended by Jobo is meant to cover 6 sheets of film on the reel. I suppose that if I load just one sheet of film on the outermost slot of the reel, the minimum could be much less. Has any experimented finding the minimum volume required to cover one sheet of film with this tank/reel combination?

Louie

 

[grahamp]

This is why I still have some ABS tubes around for doing the odd sheet.

You will need to decide the minimum volume of developer with enough active ingredient to process a sheet. Then you need to work out how much developer is needed to give the film enough time in solution when it is in the tank and rolling. The final factor is that shallow developer puddles are more likely to suffer from flow artifacts and oxidation.

Since I generally bring out the Jobo for multiple sheet tasks, I have never experimented. My feeling is that you might reduce the volume by at most a third before seeing changes in development. But that's a wild guess. You will just have to use the developer you would save in doing tests!

 

[hka]

I do it this way; by 2 sheets I use only 150 ml of dev. I put the sheets in the upper slides of the reel. When I have 4 sheets I use 270 ml of dev. as recommended by Jobo. I never use this tank and reel for more than 4 sheets. Because the flow of liquids around the reel. I mentioned a little uneven development when I put 6 sheets in the reel. Don't ask me why. Untill today I have found no answer on this. To be precisely I noticed some denser stripes at both sides of the sheets. And that only in the rotationdirection of course.

 

[antielectrons]

The film dev cookbook recomendation is:

at least 250ml of stock developer for 4 4x5 inch sheets
at least 500ml of diluted eveloper for 4 4x5 inch sheets

And they say that should be the case regardless of whether you use rotary or inversion. They say the JOBO recommendations should be ignored. So it shouds like 300ml is not enough for 4 sheets using diluted developer.

 

[grahamp]

With FG-7 / Delta 100 I need 5ml of concentrate per sheet of 5x4 as a minimum. If I want a 1+15 dilution I am getting close to the upper bound on the tank with 6 sheets. With 35mm or 120 2-up I cannot run the 1530 module at capacity unless I use a stronger solution.

So as I said, you need at least the minimum of active ingredient in the solution. With both a minimum and a maximum volume for the tanks there are some developers/strengths that require you to process less film than the tank capacity. Its the price you pay for convenience. It is also why I keep a manual tank or two around.

 

[Pasto]

Thanks to all for the suggestions. I've always felt that the film dev cookbook recomendation are grossly exagerated, but certratinly very safe. 100ml of Xtol easily processes 4 4x5 sheets with normal development. If I use 200ml of solution (Xtol 1:1) that would be equivalent to using 400ml of XTol for 4 4x5 sheets, leaving plenty of developer for extended development. I'll give it a go and let you know.

Thanks again,
Louie

 

[ras351]

According to the Kodak XTOL datasheet, 1 litre of undiluted developer will develop approximately 60 4x5 sheets which equates to about 17ml (say 20ml) per sheet (40ml at 1:1 dilution). Your mileage may vary depending on negative densities. Usually you hit the tank/coverage limit before you hit the developer limit although Perceptol at 63ml per sheet is one of the exceptions.

Roger.

 

[Pasto]

Thanks Roger. I'm clearly using too much developer. I guess I'll have to run some tests