Agitation: Intermittent inversions VS continuous rotary

[Pere Casals]

Not true! My darkroom generally runs at about 80F during the summer months and, if I start development at 70F the temperature will drift upwards by about 3 degrees over 10 mins. This will vary a bit when using stainless tanks vs plastic, but it will go up. I've tested it. And, trust me, a 2 - 3 degree shift in temp will affect the final results.

Also, I agree with Micheal W that agitation style most definitely will affect negative contrast.

easy to solve...

-Place the tank inside an Reusable Insulated Bag for food, you can even throw one ice cube in it.

- or you can use any plastic bag, with an ice cube in it...

-Place the tank in a small paper development tray with water and some ice cubes to mantain in it temperature at some 1º under your targeted temp inside the tank

-Have a little bottle with developer from refrigerator (or cooled with an ice cube), drop some in the tank just before agitations, you'll waste some 30ml of developer.

don't reuse the ice cubes later

[Peter De Smidt]

Have you seen and of John Sexton's prints in person? They are outstanding, and most of them are from negatives developed in a Jobo. I've used a Jobo for about 20 years, and I've no reason to complain. They give predictable negatives with very even processing.

[Pere Casals]

Have you seen and of John Sexton's prints in person? They are outstanding, and most of them are from negatives developed in a Jobo. I've used a Jobo for about 20 years, and I've no reason to complain. They give predictable negatives with very even processing.

Peter, an artist of the kind of Sexton usually is a master of his tools, we can guess that he selected very well his tools to do what he wanted to do, in the way he envisioned.

...and of course a rotary can deliver the results one just wants.

But IMHO it's also true that techniques based in lower agitation are a solid resource, that we can use or not.

[Peter De Smidt]

Of course. Did I say otherwise?

[Jac@stafford.net]

I am fond of my rotary drum drive that mildly oscillates horizontally to slosh the chemistry. No chance of surging agitation.

[Pere Casals]

Of course. Did I say otherwise?

No...

We agree in that rotary is an excellent system, but when we want to use agitation to control the result then we cannnot use it...

[Gary Beasley]

One effect not mentioned yet is increased oxidation rate for developers in some continuous agitation setups, air being introduced to the constantly moving developer surface. Ive found Rodinal in particular to be a poor performer in a Jobo without added sulfite to scavenge the oxygen if used in the recommended quantities.

[Vaughn]

And some pyro developers will oxidize very quickly in a Jobo. I've used Rollo Pyro with great results.

I did have some issues with the 3005 (five 8x10s) -- some bizarre staining and/or whatever on the backside of the film (non-pyro developer). Going to a non-hardening fixer took care of whatever the problem was.

[Pere Casals]

Ive found Rodinal in particular to be a poor performer in a Jobo without added sulfite to scavenge the oxygen if used in the recommended quantities.

And some pyro developers will oxidize very quickly in a Jobo. I've used Rollo Pyro with great results.

This also may be addressed by blowing (most) oxygen out with preserving gas just before closing the drum. The preserving gass is heavier than air, so it will stay mostly inside while drum is closed. I'd say that the orange cap should be placed in regular drums, in the Lift version I guess that not much fresh air would enter inside during development, but anyway we also can use a cap in the end of the pipe, I guess it would not be necessary to close the inlet.

An Oxygen Analyzer ($200) would say the actual %O₂ there.

[bob carnie]

I have used most of the process methods for film process.

Jobo Rotary- I have seen what I call minus density flow patterns with Jobo - solved by manually agitating first 15 seconds with inversion and twist - these flow marks are most noticable in grey backgrounds or large areas of grey sky.

Tray- I have a hard time with this method but many here are excellent at this and IMO all one needs

Roller Transport - the absolute worse on many levels from jams to scratches and inconsistent replenishment

Stainless Steel - cut my teeth on this and still work with this method for sheet and roll.. IMO for roll film absolutely the most control of agitation technique and pretty much fool proof

Dip and Dunk - Nothing beats a well maintained , well managed dispersion of nitrogen , and good plot...if I was to do a commercial mail in service this is the way I would go for all film.


Aside from Roller Transport the OP should be good with any of the above for good quality film process, there is no real silver bullet here, if you print your negatives you will soon learn to make good negatives or you are a fool.