Developing 8x10 in a Jobo

[terry_5379]

I am developing 8x10 hp5 EI200 in jobo expert drum on a unicolour motor base, I flip drum every 15 secs,using 800ml DDX 1+4 developer for 8mins no presoak.
When printing the edge density is some times a problem, I have changed from 240 to 300mm lens, with Devere 5108 colour head, but this has not made a great difference.Can any help.
Thanks Terry.

[jim kitchen]

Dear Terry,

I experience this issue periodically too, and although I eliminate the issue with cropping, I have not solved this problem. The edge density is very noticeable, and the increased density is always along the long edge of the film, possibly resulting from the drum's rotation. I wonder sometimes, if this is specific to this type of drum roller, and I wonder if anyone using the Jobo drum roller, with or without the processing unit, experiences this too? I do not flip my Jobo drum, as you do, since the rotational frequency is approximately sixteen times a minute. I thought my film holders leaked, but the density seems to be too even along the entire edge, and the issue is not specifically localized on the negative. This does not always occur equally on both sides of the negative.

jim k

[Andrew O'Neill]

When you say edge density, do you mean increased density or less density? I'm assuming increased density...I'm not familiar with jobo equipment. How much solution do you put in the drum?

[terry_5379]

I have to burn in edges,800ml in drum.

[Death Valley Phil]

I gave up developing 8x10 (B/W) negs on the Jobo, went to hand rotating the drum with very uneven rotations, rocking back and forth etc, that helped a lot and allowed me to do four negs at a time, the most I'd do on 1000ml, but for a while now I have been tray developing, with perfect results every time. I was told some time ago, you can't do 8x10 in Jobo or any other drums and expect clean consistant results ...I should have listened....Phil.

[tim atherton]

I've had a few such problems with the Expert drum on a Unicolor base with HP5 and Xtol - though a switch to DDX basically seemed to fix it.

One other thing I did though that helped with other developers is introduce some unevenness in the motion. I took some of that stuff like putty you use for sticking posters etc on walls (used to call it Bluetac in the UK?) made a little lump of it and put it under the rubber of only one of the roller wheels. Just enough so it gives a little lump, not enough that ti impedes the turning of the roller wheel though. This gives a very slight longitudinal wobble...

So, as well as the rotating motion, you get a very gentle and slight swishing motion along the length of the tank. This really seems to make a big difference. (every dozen tank loads or so, I found I needed to "re-squish" the bluetac...)

But since I got a Jobo processor I've had no such problems with 8x10 at all - HP5, FP4 Efke 100, Tri-X (and 4x5) in DD-X, D23, Xtol and Pyro - the most even scratch free negs I've ever had (and I've done trays, BTZS type rollers and 8x10 Kodak rubber tanks with negs in holders)

I was told some time ago, you can't do 8x10 in Jobo or any other drums and expect clean consistent results ... = load of old codswallop imo

[Jay DeFehr]

Jobo Expert, ATL 2 Plus, Hp5+ EI 400, 510-Pyro 1:100, 1 liter solution, no problems at all. In fact, my results with rotary development have been as consistently excellent as my results developing in trays, one sheet at a time, with brush agitation, which is to say, as close to perfect as I'm capable of recognizing. Of course I can't DBI with the Jobo, but I think that technique was mostly just a really fun experimental phase for me. It was quite liberating to learn just how primitive my process could be, and still produce beautiful results, and I'm glad I learned the technique, but for my day to day work, rotary processing is far more practical and precise.

I suspect your problem is related to your roller base. If you have room, try rolling your drum in your sink/on your table/floor etc., and stand your drum on end occasionally during development. You might also check your film holders for leaks, if you haven't done so. I use RC printing paper to check my holders, and it's good practice. I hope you find a solution to your problem, there are too many things that can go wrong with an 8x10 exposure to add to them in the darkroom. Good luck.


Jay

[John Powers]

Terry,
I have been using 8x10 T Max 400, Rollo Pyro, Expert drum, CPP-2 Jobo for about two years and am very happy. I have only used a 300mm APO-Rodagon Rodenstock, but have a 240mm if needed. This is on a Durst 138S converted to 8x10 Aristo cold Light. Most of the time I print just inside the negative edges, 1/8 inch to 1/4 inch in unless there is a change from the image I originally planned to a crop for some reason not earlier considered. If I can help with any of that please ask.

I am also doing 7x17 but only two at a time so the return on time invested is not as good. Quality of results is good though and of course these are contact printed to the edge.

John

[Ed K.]

Hi Terry,

Because you mention changing your printing setup, have you verified that the edge density is really the issue? Also, have you tried developing an evenly fogged sheet of film? More density on the edges, or less? All edges, or just two?

Aside from that, I get really even results with the Jobo and drum setup - more even than the local lab's Refrema setup and more even than trays with brushes. The only problems I've ever had were with very short developing times. Sometimes it helps to have a little longer developing time (with dilution, etc.) - times of 9+ minutes are more consistent than times under 6 minutes, however I've had good results with 8 minute runs.

The Jobo turns the drum pretty darned fast - that creates a special turbulence inside. Maybe you are getting a different flow pattern inside by rotating too slow or fast. The Jobo switches directions about every 4-5 seconds. It seems like it would be too much, but it works out great.