Rotary Processing: Ilford DD-X Volumes

I had been taught standard inversion small-tank processing a long time
back, and am recently returning to self-processing black and white
films. This time, though, it's with a Jobo rotary processor.

I had always used 250-300ml per roll of developer (whatever would
cover the reels in the tank), but the Jobo docs and conventional
wisdom prescribe a smaller chemical volume in rotary tanks (the 2523
tank I use most often has a minimum of 270ml). Looking at Ilford's
PDF on their liquid concentrates, they say that a liter of DD-X can
process up to 10 135-36 rolls, with developing time increasing by 10%
per roll. From this, I deduce that each roll effectively consumes the
capacity of 1/10 of a liter, or 100ml, with the extra time caused by
the inhibition to development caused by reaction byproducts. So far,
so good - I think. Ilford doesn't explicitly state the film area
capacity of their formulations, so I'm guessing a bit.

I know I should just shoot some test rolls of a properly exposed
subject and dunk'em, but I hate wasting two full rolls of film if I
don't have to. So - if I rotary process 2x135-36 rolls in 300ml of
DD-X, do I have to make any time adjustments. More importantly - am I
mad just for asking?

 

No you're not mad for asking. But you're missing the the trees. The bigger
issue is the constant rotation. Odds are you'll have to cut the development
time to compensate. How much? You'll have to test.

Nick

 

I've been holding to 20C temps and decreasing development time by
about 15% from Ilford's dev charts to compensate for constant
agitation when using DD-X. That's worked well for me. I get good
tonality without excessive density with Delta100, HP5 and Pan-F so
far. I started with Ilford's recommended 10% reduction, but was
getting slightly blown highlights.

I've got a few dozen rolls under my belt with this setup, but I've
been souping them in inversion quantities - usually 600ml for two
rolls and 300ml for a single. I think (and have been led to believe)
that such a volume is unnecessary, but I haven't been able to get a
straight answer yet as to the necessity of any time compensation when
using a lower volume. I should be able to use a straight 300ml volume
for the 2523 tanks and leave it at that.

From reading others' experiments with the same thing, I don't believe
I have to compensate, but no-one's come flat out and stated such
anywhere. Maybe I should just run this afternoon's batch with 300ml
of DD-X at my normal times and see what I get. Or maybe I should just
throw a couple rolls of HP5 through the F4 at maximum motordrive speed
and just process them to get my answer.

Thanks for your help.

 

Well, I answered my question - I shot two test rolls of two subjects
with a fairly full range of tones, and processed them in 300ml of DD-X
1+4. Negs look fine out of the rinse. I'll loupe them when they're
done drying, however they don't seem to have density issues.