Uneven development...

[SAShruby]

I just recently started to scan my 8x20 negatives I developed a year ago or so and I discovered that I have a serious issue in my development.

In my third negative I see same uneven development, it clearly shows in highlites. The unevenness is always the same, in direction of JOBO rotation, on same places. It looks like different amounts of developer are running over the negative, making it uneven?

My development is as follows: I use JOBO levelled perfectly with 16x20 inch print drums, it's a print drum with the extension, running slightly higher than F speed, using revesal-rotation mode, developer is X-tol 1:1, I use 1 liter of developer just to be on a safe side.

I use same technique with 4x5, everything is just fine and even.

Unfortunately, this development technique make development problems on 8x20. I also have 6063 drum but I think that one would be just too big.

What should I change? Running on higher speed? More developer? Lift the negative in a prin drum?

Thanks.

[Bert Hillebrand]

Hi,
I had experienced uneven developing in the Jobo CPE2 on 4x5 films and was advised to start rotation with a quantity of temperate water for a few minutes, drain it and then pour in the developer. In this way the developer makes contact on the entire 20 inch film much faster.
Regards,
Bert Hillebrand

[sanking]

Peter,

There are several possible remedies.

1. Remove the drum after about a minute of development and rotate it on the horizontal axis by turning it in your hands while raising and lowering each end. Repeat for about ten seconds every minute or so.

2. Reduce the speed of rotation as much as possible. Very slow rotation is much better than slow and slow is better than medium speed and medium speed is better than fast.

3. Use a more dilute solution. For example, instead of D76 1:1 try D76 1:4.

Taken together these steps should eliminate the problem of uneven development you are having.

Sandy King

[Pete Watkins]

I had similar problems at one time then I started to lift the drum from the rollers every minute or so and gentley rock it from end to end for a few seconds before replacing it. This is exactly what Sandy recommends under No.1.
I always pre-wash as well, except when I use Ilford film (which is never these days, not at those prices).
Best wishes,
Pete.

[bob carnie]

I was getting uniform uneven development with rotary processing and tried everything.

Finally solved the issue, by manually agitating the first 30 secs of development rather than putting on the machine.
Overnight I got rid of a very serious problem which was stopping all our commercial processing.

[SAShruby]

Thanks guys, much appreciated.

[Jim Noel]

I have always pre-soaked for a full 5 minutes in the Jobo and never had a problem with streaking on films up to 7x17.

[sanking]

I have always pre-soaked for a full 5 minutes in the Jobo and never had a problem with streaking on films up to 7x17.

Yes, I would add the pre-soak to my list of remedies.

However, the real key may be in imposing a very random type of agitation early in the development process, as Bob Carnie has suggested, and I alluded to in an earlier message.

The issue is that any uneven development that is allowed to begin early in the development cycle will get more pronounced with time. For example, if you allow water or developer to splash on part of the film and remain there for a few seconds before the film is fulled wetted out that area will most likely show some uneven development at the end of the process.

Sandy King

[SAShruby]

I always soak film for 5 minutes, regardless the size of the negative. The only thing what I can think of is that I pour developer as the drum rotates and.. it takes time... sometimes up to 10 seconds when entire liquid is in.

Could those 10 seconds be a problem, probably another 5 when liquing is getting even in the drum? Would be better to pour liquid first, while drum at rest, negative positioned on the top of the print drum and then turn on Jobo? Any thoughts on that?

[bob carnie]

We are building a monster film processor see Apug ** my jobo's are on their last legs** thread.

We will incorporate a manual initial agitation with all film , C41, Pyro, D76,HC110.
I think this is critical when using a rotary process. It seems to me the most critical step and as Sandy says initial problems will only get worse as the development continues.

If I think I could encourage my staff to manually agitate tanks I would for the whole process, but practical experience tells me that it is hard to motivate someone to do this as a day to day job, and if they get in a bad mood the quality or contrast, edge problems start showing. Therefore the luxury of automated rotation is worth its weight in gold.