Lost the plot - Pyrocat in Jobo

Hello

I have recently changed Jobo processors from an ATL-1000 to an ATL-2300. After my first runs, I have made some changes, but having consulted my range of books, cannot see a way to get me back on track. There seem to be a lot of possible variables and I have lost the plot on which is likely to be dominant .

When attempting B+W for the first time in the new machine, the negs came out under-developed having set the process as for the previous machine. The only exception was that I reduced the rotation speed to 25rpm having read for Sandy's article that slowest speed gives lowest base and overall staining. The roation speed of the ATL-1000 is fixed (about 75rpm I think).

Normally I have been using 1:1.5:100 equivalent (actual 1:7.5:100 with Sodium carbonate) at 21 deg C. Time is 10 min 45s for Fuji Acros rated at ISO 80.

For the 2nd film I altered to 1:2:100 equivalent at 21 deg C, which brought some improvement but was still lower density than on old machine.

The third film, I again used 1:2:100 equivalent, but raised temp to 24 deg C. This produced a contrasty film which looked ok on the lightbox.

I processed 3 further films at this setting, but realise that the extra contrast is not helpful. Deep shadow detail is missing too.

An obvious thing is to change the rotation speed back to 75rpm, but couldn't find anything which demonstrated the effect of the difference in agitation. The higher temp seems a bit extreme and everyone else seems to get on fine at 21 deg C.

I am not sure how quickly the developer oxidises. The Jobo can take a while (5-10 min) to start process if it is not at correct temp when Start button is pressed. I do endeavour to get chems and bath water close when filling (Using Jobo water panel). FWIW I use Pyrocat HD which I made in the late Autumn and it has been stored in small containers in a cold dark room.

There is a backlog of film which need processing and I am keen to get back on track. Suggestions please.

Baxter, I don't use rotary processing, so take what I say with a large pinch of salt. Reducing development agitation has the effect of slowing development. It seems to me you have two out of too many choices here to consider.

If the old system was working, why not just go back to what worked already? I'm sorry, but I'm a bit confused, is the new machine not capable of the correct change in rotational speed? This sounds like the easiest solution. If you liked the old results and have a lot of film to process, it sounds like the best bet for now is to return to that speed and just plow through the backlog of film.

If you wish to go with the slower speed, an increase in development time would be the logical point to start. Changing too many variables can be too confusing. This is all such a fine juggling act already that changing speed, concentration and temperature is too much to track. Once you have changed more than one variable (without testing first) you are in no man's land as results are meaningless. Since I can't help you with the actual numbers, I would say to go back to the original dilution and temperature, then add time for the reduced agitation rate. My best guess (and it is only a guess) is that you will have to add, perhaps, a full stop of development in time to compensate for the slower speed. Sorry I can't be of more help. Best, hang tough, tim

P.S. You can borrow the moaning chair from my darkroom, if you want to pay shipping.
P.P.S. My dunce hat has to stay here, as I'm planning on shooting this weekend.

Baxter Bradford said:

Hello

I am not sure how quickly the developer oxidises. The Jobo can take a while (5-10 min) to start process if it is not at correct temp when Start button is pressed. I do endeavour to get chems and bath water close when filling (Using Jobo water panel). FWIW I use Pyrocat HD which I made in the late Autumn and it has been stored in small containers in a cold dark room.

There is a backlog of film which need processing and I am keen to get back on track. Suggestions please.

Click to expand...

One would expect that changing rotation speed from 75 RPM to 25 RPM would result in a significant decrease in contrast so to compensate you should increase time of development. I would suggest, without any particular authority, that 25%-50% more might be in order. I know that a change in RPM can make a significant difference in contrast because I test single sheets of film in a drum running on a fairly high RPM motor base, but multiple sheets in tubes with very gentle rolling agitation. For ten minutes with the 1:1:100 dilution the Dmax will be about 1.2 with tubes, but about 1.6 with the drum on motor base.

If your developer was mixed in late autumn, and is stll clear, I would be reasonbly confident that it is still performing as it should. My experience, and the accumulated information posted by others, suggests that the shelf life of uncontaminated stock solutions of Pyrocat-HD is at least a year. If you mix your own, however, the stuff is very inexpensive so just mix a new batch and compare it to the other.

Sandy

Baxter Bradford said:

I processed 3 further films at this setting, but realise that the extra contrast is not helpful. Deep shadow detail is missing too.

An obvious thing is to change the rotation speed back to 75rpm, but couldn't find anything which demonstrated the effect of the difference in agitation. The higher temp seems a bit extreme and everyone else seems to get on fine at 21 deg C.

Click to expand...

Two more comments. With regard to deep shadow detail missing, this is most likely an exposure issue, not a developer problem.

As for RPM, if you are developing for printing on silver papers there is no need to be concerned about rapid RPM. I recommend slow RPM because it minimizes the formation of B+F stain in the UV, which is only of concern to alternative printers exposing with UV light sources. . B+F is not normally an issue for people who print with silver.

Sandy

Thankyou Tim, Jay and Sandy for this helpful information.

This advice and some time to clear my head has been very beneficial and I shall have another attempt to get it back on track soon. My two children are on their Easter holidays, so this is curtailing my photographic activities somewhat!

The developer is clear, but I have some more which has been stored in full, airtight bottles, so ought to switch to using one of these and then alter the rotation back to 75rpm and 21 deg C for my next attempt. I do not use alternative processes for my prints and I wasn't worried about base fog when using previous processor.

Tim, I am well furnished in the Dunce's hat department, but feel that a moaning chair might be a sensible acquisition!

Thanks again