Jobo Problem

[Mamiyaissues]

I need your help, I have been using a Jobo CPP2 for several weeks and I have two problems. The first is that these bubbles appear repeatedly in my negatives and I don't know where they come from, what process is it happening in, is it in the stabilizer? The second problem is that my negatives are coming out very clear, as if they were low in temperature but they are developing at 38 C and I already increased the agitation to 3 and they continue to come out the same.

 

[Nicholas Lindan]

The bubbles are from foam in the developer (? - might be some other step, but developer is the culprit in B&W).

Do you have the drum rotating when the developer is poured into the drum?

As to temperature - have you checked the water bath temperature with an independent thermometer?

 

[mshchem]

Welcome to Photrio.

 

[Omid_K]

The negatives look thin (under developed) to me. I set my rotation to P for 35mm/120 film and I use 4 for large format sheets. I read to set those settings somewhere long ago.

Was this roll after setting the setting to 3 or was this set to a lower rotation speed? Also, what steps do you take to ensure the temperature stays in a good range during development? If the temps were off by the end of development by a few degrees and the rotation wasn’t as vigorous as needed, this could reasonably be suspects in the under development.

I had a thread with Mike Rollins a while back and he clued me in on all kinds of variables that affect temperature. I ran experiments with different bath temperatures and also different temperatures to pour chemistry at. I had naively assumed that I could drop in chemistry at temp with the bath the same temperature and have it all good. But Dave was right, and I lost temperature far more than I realized. Big thing is to take the temperature of the chemistry once it’s poured out to see what the temp drop was. Once you go through all that hassle, it becomes easy to get consistent results with the Jobo.

Just don’t forget to run tests in both cold and warm seasons since the ambient air affects everything too! Think about it, half the Jobo tank is air as it lays on its side.


Omid

 

[koraks]

The first is that these bubbles appear repeatedly in my negative

As @Nicholas Lindan mentions, they are due to excessive foaming in the developer, but this problem also suggests a lack of agitation and/or insufficient developer volume. Generally with a rotary development process, foaming doesn't matter since the foam is continuously displaced by liquid developer, so it doesn't matter it's there. Color developers often have wetting agents added to them which tend to foam, so it's natural for some foam to be present in the developer.

This brings the question:
1: Which tanks are you using and how much developer volume (milliliters) are you using? If you're using insufficient developer for your tank, you can run into problems like these.
2: How long does it take between the tank being filled with developer and rotation starting? If it takes too long between filling the tank and commencing rotation, you can risk uneven development. It should only take a few seconds between filling the tank and starting rotation.
3: How much time is there between dumping the developer and pouring in the next bath (stop or bleach)? If this is too long, foam can remain on the film and the edges of the bubbles will cause additional development in these areas.

The second problem is that my negatives are coming out very clear

This points to either of the following, or a combination:
* Developer not on the temperature you think it is (too cold)
* Insufficient developer volume (see above)
* Insufficient developer activity due to it being too dilute or underreplenished (e.g. developer reused for too many rolls of film)
* Too short development time; C41 development time at 38C/100F is 3m15s nominally.

Judging by how thin your negatives look, this is not an issue of temperature drifting by one or two degrees; you wouldn't get this much underdevelopment it that were the case. It's either a massive deviation in temperature (5-10 degrees) or some other factor at play. I put my money on the latter.

It will help if you could answer the questions above and indicate to what extent you've already tried mitigating the causes that were mentioned thus far for underdevelopment.

And welcome to Photrio!

 

[Sirius Glass]

Welcome to Photrio. Follow the advice from @koraks and @Omid_K ==> more chemistry and more rotation speed.

 

[grahamp]

Do you have a Lift on the machine? A Lift and manual tank handling can take different amounts of time, which can affect the actual development time.

Do you put wetting agent in the tank, or the spiral in wetting agent solution before hanging up the film? Wetting agent carry over from a previous development cycle can cause foaming.

Expert tank, or a 1500/2500 series one?