Effect of constant agitation?

[ChrisN]

In processing traditional black and white film, and in general terms, what is the effect of constant agitation compared with the standard intermittent agitation?

I'm wondering about the impact of using a Jobo-style processor, with constant rotation of the developing tank (with tank laid horizontal), as compared with traditional small-tank development with a couple of inversions every minute.

What is the effect of constant agitation on accutance?

Does constant agitation reduce development times?

Any other impacts?

Thanks. 🙂

To explain, when I was experimenting with Rodinal 1+100 stand development, I occasionally got stunning results, but more often got streaks on the negs. Introducing some agitation got rid of the streaks, but regular even occasional agitation during a one or two hour development time is itself a serious chore that negates the benefits. If I can automate the agitation (with constant rotation), it would solve that particular problem. (Note that I am not pursuing the reputed benefit of stand development in preventing highlights blowing out. Rather I wish to explore the limits of developer dilution. Strange, I know, but it might be fun.)

 

[MIkhail]

Agitation increases the contrast. I personally prefer less agitation than even recommended "on the box".

 

[Thardy]

Depends on how aggressive you agitate I would guess. I've tried stand dev, but always would run and give a couple of inversions " just in case".

Continuous gentle agitation might not cause too much increase in contrast, if any.

 

[ChrisN]

Interesting. I'm thinking of a tank laid horizontal, rotating smoothly at 3 rpm.

Extending development time increases contrast too, so I guess if I plan to use constant rotation I can reduce the development time to control the contrast.

 

[MIkhail]

Depends on how aggressive you agitate I would guess. I've tried stand dev, but always would run and give a couple of inversions " just in case".

Continuous gentle agitation might not cause too much increase in contrast, if any.

Always does for me.

 

[ChrisN]

Mikhail - that's with normal small tank ( a few inversions by hand, every minute)?

 

[Thardy]

Constant agitation , increase contrast.

Constant agitation , increase contrast.

Always does for me.

Yep, experience is better than speculation.

 

[MIkhail]

Mikhail - that's with normal small tank ( a few inversions by hand, every minute)?

Yes, just small metal tank with 2 simple metal reels. I find them working best and loading quickest, opposed to the plastic ones. Learned in college where they used cheap and durable stuff in lab.
I never had JOBO so I dont know how it would work there though. But I would expect the same effect...

 

[Sparrow]

Interesting. I'm thinking of a tank laid horizontal, rotating smoothly at 3 rpm.

Extending development time increases contrast too, so I guess if I plan to use constant rotation I can reduce the development time to control the contrast.

It's many years back, and my notes will be long gone, but I seem to recall it slowed down the reaction and I had to extend the times.

Somebody must have one and know what's what, surely

 

[scottyb70]

Take 15% off the recommended time. D76 and tri x works the best in a jobo setup.

 

[degruyl]

This is a perfectly normal way to develop film. From normal agitation (10 seconds every minute) to continuous you reduce developing time by about 20-30% to achieve the same contrast ratio. (testing required)

Depending on the developer, this may (probably will) reduce acutance, which is increased with reduction in agitation. Have you looked at Pyrocat-HD? If you are trying for acutance, a tanning developer appears to make a difference in localizing the developing based on the exposure. (the staining is interesting for other reasons, especially producing negatives of very high contrast)

 

[venchka]

Since I emerged from my Photographic Black Hole in 2006 and began developing film after several decades of inactivity, I have used a Jobo tank on a motorized base (Uniroller & Beseler) @ 30 rpm with Xtol 1:3 and Rodinal 1:25, 1:50 & 1:100.
Films used include:
Kodak T-Max (all 3 emulsions), Plus-X & Tri-X.
Ilford HP5+, PanF+ & Delta 100.
Arista/Foma 200.
Efke 25.
Everything that I have developed this way in Xtol 1:3 pleases me. Rodinal and continuous agitation isn't as perfect as Xtol. I must agree with Earl (Trius) that Rodinal benefits from reduced agitation. I have had good results with film sitting in Rodinal 1:100 for an hour. Earl suggested Rodinal 1:100 and agitation every 3 minutes or so for about 20 minutes depending on film. That may be the best way to use Rodinal.
Good luck.

 

[Denis M.]

Agitation increases contrast because it constantly brings over fresh developer to the highlights. I think that's how it works. For continual agitation you'd need to scale back your development time. I'm not sure how much. I think it doesn't work too well with push-processing.

 

[shadowfox]

My Unicolor drum rotates back and forth slowly at about 6-rpm (if it were to rotate one direction continuously).
All my 4x5 up to 8x10 are developed in that drum.

So far I have no problem with uneven development or unwanted high-contrast.

 

[Ronald M]

Cut 15% from the every 30 sec inversion cycle time and you will have close to the correct time for constant agitation. Negative will print the same.

To go from 30 sec cycles to 60 sec cycles, add 10% to every 30 sec cycle time.

With a stainless tank, use a two reel tank with only one reel with film and use 250 ml of developer. Roll 1.3 times the circumference of the tank, then reverse. This is actually an extremely good agitation scheme whether you constant. 30, or 60 sec cycles. You will need a plastic mat so the tank does not slip/skid.
I used to do it for 60 sec cycles with left, right,left. right every minute. works a treat.

Never tried this with plastic tanks with the oversize lids. I would start by hang the lid over the edge of counter. There is a lot of empty space in the lid so I have no idea how much volume of liquid to use. In any case, it is close to impossible to make an error with a plastic tank providing you follow the instructions, which say, pour in developer, use twist stick for first agitation cycle only, cap and invert for all the rest. Deviate at your own peril.

 

[Tom A]

Some developer/film combination works well with cont. agitation. I use a UniRoller - 6-7 rpm - with a 3 rotations in one direction - then 3 in the other.
Best result has been with Neopan 1600 - rated @ 1000 and Rodinal 1:100 for 14 minutes.
Pyrocat HD needs continious agitation for the first minute - then regular flip/twist for the remainder of time. If you do it for the full duration, the contrast goes way up!
Most split developers work well also, TD 201 for 3 min. in A and 3 min in B comes out fine - without excessive contrast and no speed loss.
If you are thinking of trying it - do the rotation in "forward and backward" direction - if not, you can get cavitation streaks across the film from the sprocket holes.
I use full Paterson tanks, 1500 ml, as they fit nicely on the UniRoller - biggest problem is the weight of the tank - it does wear heavily in the roller. Smaller tanks (3 reel) keep wandering across the rubber drive wheels and you have to stand there and keep an eye on it. Also be sure that the lid is secure - I have had one pop open and flood the sink!
The rule of thumb seems to be cut time by 1/3 for continious agitation - but do a test run before committing "important" shots to it.

 

[Colin Corneau]

FWIW, on the subject of stand development -- I used a standard steel reel/tank. Rodinal 1:100...2 hours with 5 inversions to begin with, 5 at the 1 hour mark and just emptying at 2 hours.

Negs turned out perfect (FP4, 35mm) with no problems. This is the first time I've tried stand. The key is having a good movie to watch while you're waiting. 🙂

 

[BillBingham2]

Gray hair!

Silly rabbit.......

B2 (;->

 

[ChrisN]

Thanks everyone! The general concensus (apart from BB2's comment 🙂 ?) seems to be to cut dev time by 15% or perhaps a little more. At the moment my standard film and developer is TRI-X @ 400 in ID-11 1+3 for 20 minutes, so I'll give that a try at 17 minutes for starters and to give me a known reference point.

A normal dilution of developer is obviously not exhausted at the end of a run, or else developing time would not be so critical (longer development means increased negative density in the highlights especially - therefore higher contrast). Short development times seem to have evolved for convenience, especially with hand agitation, but require careful attention to time, dilution and temperature.

One interesting aspect of stand development is the prospect of exhausting the developer, irrespective of development time, at the point when "correct" development has been achieved. I've used 4ml of Rodinal per roll of 135 film, in varying quantities of water, and achieved reasonable negs (albeit with streaking from too-little agitation). I wonder what the minimum amounts of other developer are, for example with ID-11, or LC-29?

Cheers!

 

[ChrisN]

First test has come out OK.

TRI-X at 400, ID-11 100ml of stock plus 300ml water at 21c (400 ml total), 18 minutes of development time.

For your amusement (and I know Tom will appreciate this) here is my home-made rotary processor Mk I. The black box on the right-hand end is a BBQ rotisserie motor that runs on D-cells at 3 rpm. That drives the shaft which is supported in two bearings held to the stand by two worm-thread hose clamps. On the other end of the shaft is a length of 110mm OD plastic sewer pipe with an end-cap glued on. That's just the right size for a Paterson tank to slip inside. There's a velcro strap to stop the tank slipping out. The motor only rotates in one direction, so the rotation is continuous with no reversal.

The test roll is hanging up to dry, but development appears to be very even with no sign of the cavitation from the sprocket holes that Tom (and others) have warned about. I think this might be because the rotation is in line with the length of the film. Contrast looks good, but I'll need to print and scan to check fully.

If further testing indicates this is worth pursuing I might even paint the metal bits, and mount the whole thing on the splash-panel above the sink!