I am using Jobo Expert Drum for 4x5 processing. Often I have the problem with uneven processing. There are areas on the bottom part of the negative, usually right next to the edge, which seems to receieve no chemistry. Strikingly, sometimes they clearly received developer but did not get the fixer. I always load the film dry, then prewet for two minutes and proceed to processing. I use the drum on unicolor roller. I will appreciate any advice to solve this pretty frustrating issue.
Jan
Is the drum leveled when you're using it on the roller, so that solution flows to the end of each compartment?
Yes, the drum is leveled. I wonder if it has to do with "stright" loading of the film. I never payed attention to that but just saw that Jobo reccomneds the film edge ideally parallel to the edge of the compartment. Could this cause a problem?
Are you using the unicolor roller that reverses after about 3/4 of a turn with that drum?
If so I would remove the mechanical reversing switch and let it run in one direction and it will be fine. I use the 2509 reel with a 2500 series drum on a homemade roller that works fine.
2nd, Howmuch volume of chemistry are you using?
What drum are you using?
I use the 3010 on a Beseler motor base with no problems. Although Ilford and Kodak don't recommend a presoak, I do one as well and have no issues with uneven development. With the 3010 drum it is pretty difficult to not load the film straight, and having used the 3006 several times I never had a problem when loading the film.
Are you using enough chemistry?
Recently I noticed some problems with my negatives with a straight line of what appeared to be under developed areas. At first I thought it was the processing but it turned out to be a fogged area of film from pin holes in my bellows. So, perhaps it is not the development process but an issue with the camera or even film holders.
Just a thought.
Good luck!
I have already removed reversing swich so it rotates in one direction only. The volume of the developer is always 300-350ml. I use more of the fixer, usually 500 ml. But I think the volume is not where the problem is as sometimes I see these araes developed but not fixed. This seems wired to me because if the drum was not correctly leveled or there was an air bubble trapped somehow, or there was not enough chemistry volume I would never see these areas developed, I guess. Maybe the film moves somehow inside the drum while I pour the developer out, but it does not sound likely to me.
This is 3010 drum. I do not think the problem is related to the camera or film holder. I can clearly see the area which was not developed or not fixed. This is not just darker area, it is unprocessed emulsion. Sometimes there is an stright line on the bottom edge of the film which looks like this, more often there is irregular "spot" right next to the bottom edge. Sometimes it is really bad - 3 out of 6 negatives can be affected.
Is there any way you can post an example of a problem negative?
Are you using two sheets per tube or only one? ( I always try and use two, in fact I will keep old, dated film as "filler" to make sure there are two sheets per tube)
If you do both single and double at times, does the problem occur when using the two sheets per tube versus the single sheet per tube?
Or does it occur no matter how many sheets are in each tube?
Have you checked each tube to make sure there is nothing broken that might be allowing one film to touch the other while processing?
Have you tried to increase the amount of developer to 500ml as opposed to 350ml? I tend to use more than what Jobo recommends.
This is a difficult one, I seem to feel it is either a mechanical breakdown somewhere along the way or not enough developer in the 3010.
Thanks
The sheets are maybe overlaping.
I always load rights leaving 1/2 in sticking up, then the lefts. Then push them both down.
Feel both ridges that are supposed to separate the sheets. If you can`t feel it or the sheets do not go down straight between the ridges, they will overlap.
Before you start removing the film next time, shine a light down to see how they are loaded so you can acesses if this is the problem.
I use a similar setup as you do, but the 2500 series drum However, some "rules' apply to all drums, so . if you want to try, a couple things I would try changing:
1) most problematic, as I see it, is constant rotation all the itme in one direction. I would physically pick up the drum once *every* minute and rotate it so it is going "backwards" compared to the direction it was just going.
2) Use more developing solution, regardless of type of developer used, in any Jobo drum than Jobo calls for. As a rough rule, increase by 20% , and experiment form there.
3) how fresh is your fixer? Personally I am a great beleiver in one shot developing. One shot developer,a nd I only reuse my fixer the actual day I am processing. Weakening your solutions down, nd increasing your development times correspondingly is not only economical, but IMO, allows you more control over your development. Anyhow, very easy to exhaust or cross contaminate fixer and other chemistry when not using one shot developing, so check over your steps one by one.
4) Increase your presoak time. I use 4 to 5 minutes in my 2500 drum. Your milage may vary (YMMV).
...and one last total shot in the dark..what kind of developer are you using? Some powdered developers cam giv eyou odd results if not mixed properly. Liquid ones too I suppose, but I see it more with powdered developers.
good luck
joe
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