Constant Agitation

[hoffy]

OK, we have a thread about intermittent agitation (a very good thread indeed)....how about one about constant agitation!

From what I have seen, constant agitation is generally achieved by some form of rotational device. How important is:

• constant speed of the rotation?
• reversing the direction from time to time?

My Jobo is a bit of frankenprocessor, which at times means the rotation is not always the same as the previous run. It also sometimes doesn't change directions. Is there going to be a measurable difference in results? (I have only used the jobo twice before for processing film).

Cheers

 

[Neal]

Dear hoffy,

Years ago I purchased my first Jobo 25XX tank and built a quick motor drive for it that did not reverse. There were no ill effects noted and the Xtol times for rotary tubes worked without problem. A few years later I added a water bath and a reversing drive and it all works great but there has been no improvement.

Good luck and enjoy!

Neal Wydra

 

[bvy]

Not sure we needed two threads; it's hard to talk about one without the other. Anyway, I develop 4x5 film in a Unicolor drum on a reversing motor base. The contrast is good, the development is even. I do cut back the time slightly (20%?) to account for the constant agitation.

 

[hoffy]

Not sure we needed two threads; it's hard to talk about one without the other. Anyway, I develop 4x5 film in a Unicolor drum on a reversing motor base. The contrast is good, the development is even. I do cut back the time slightly (20%?) to account for the constant agitation.

Good point....maybe a mod could merge these together and rename to just "agitation"?

 

[mrred]

i think this discussion would get lost if they were merged. On that note, my motor base is only one direction. I compensate by making sure the film on the reel is positioned to scoup up the developer. No uneven development, aside from xtol accelerating developing around the perfs on 35mm film.

Sent from my BS970 using Tapatalk

 

[RalphLambrecht]

OK, we have a thread about intermittent agitation (a very good thread indeed)....how about one about constant agitation!

From what I have seen, constant agitation is generally achieved by some form of rotational device. How important is:

• constant speed of the rotation?
• reversing the direction from time to time?

My Jobo is a bit of frankenprocessor, which at times means the rotation is not always the same as the previous run. It also sometimes doesn't change directions. Is there going to be a measurable difference in results? (I have only used the jobo twice before for processing film).

Cheers

Hi Hoffy,
as you probably know,I'm using a Jobo for fil processing for years.all my film tests are done with it and the results from the test are constant.if a film is processed as it was tested, there should not be a deviation or issue,I always use the higher speed with reversing without a prewash,which I consider a waste of time and counterproductive.My negativesare always evenly processedand very predictable in density;no surprises My own processing is far better than what I've gotten from the so=called pro labs before;D761+1@20C

 

[Vaughn]

I use constant agitation when developing sheet film in trays -- and of course in Expert Drums on a motor base.

My motor base does not reverse. I disabled that because the 3005 tank would not rotate enough in one direction before it reversed. So I pick up and turn the drum around every 30 to 60 seconds...seems to work fine.

 

[cliveh]

I use constant agitation when developing sheet film in trays

Why? no agitation is as important as agitation.

 

[Maris]

I tray develop sheet film, one sheet at a time, with constant agitation. Why? Because it gives me something to do during those minutes and hours in absolute darkness and it removes agitation as a wild card influencing development outcomes. When there's only time and temperature to control results are remarkably consistent.

 

[ic-racer]

It will be a useless thread unless someone posts some densitometry results on evenly exposed frames comparing the processes in question.

 

[mrred]

Not useless. Just may not answer a density question you have.

 

[Vaughn]

Why? no agitation is as important as agitation.

I do not believe periods of non-agitation are required for proper film development.

I would say consistency is as important as both agitation or no-agitation. Constant agitation is easier to keep consistent while day-dreaming in the dark.

In trays I tend to introduce the sheet into the tray, emulsion down...then a few flips (odd-number) that leaves the film emulsion up. I push the film to the bottom of the tray and do gentle agitation for the remainder of the time...semi-randomly changing the agitation direction (avoiding a pattern of movement in the tray).

 

[cliveh]

I do not believe periods of non-agitation are required for proper film development.

I would say consistency is as important as both agitation or no-agitation. Constant agitation is easier to keep consistent while day-dreaming in the dark.

In trays I tend to introduce the sheet into the tray, emulsion down...then a few flips (odd-number) that leaves the film emulsion up. I push the film to the bottom of the tray and do gentle agitation for the remainder of the time...semi-randomly changing the agitation direction (avoiding a pattern of movement in the tray).

Are you familiar with stand/still bath development? If so you may appreciate why agitation and non agitation are both important aspects during development.

 

[Vaughn]

Are you familiar with stand/still bath development? If so you may appreciate why agitation and non agitation are both important aspects during development.

I apologies, I was only referring to my development needs, not film development in general.

Yes I am familiar with both stand and semi-stand development. Non-agitation is not a factor (and thus is important only in its non-importance) since I do not use it (there is no periods of no agitation in my development methods -- either using trays or drums). What a lovely set of negatives in that sentence!

I rarely, if ever, need to reduce the contrast range on the negative through development. And about 95% of the time I need to increase it. Therefore, constant agitation suits my needs very well.

 

[hoffy]

OK, when going from times that are based around a agitate/sit routine, what is the rule of thumb in time reduction when doing constant agitation? BVY suggested 20% on page one. Is this, though, a 'starting point' only and a case of mileage varying?

 

[bvy]

OK, when going from times that are based around a agitate/sit routine, what is the rule of thumb in time reduction when doing constant agitation? BVY suggested 20% on page one. Is this, though, a 'starting point' only and a case of mileage varying?

I think you have to experiment to see, but 20% seems a good place to start. I arrived at that figure by looking at some of Kodak's spec sheets that give side-by-side times for constant and manual agitation of different films.

 

[pentaxuser]

I have said this before but I'll risk a repeat. NB I take this from a book and not from personal experience as I don't use a Jobo processor for trad B&W.

In his book "The Rotary Processor Manual" the author John Tinsley uses the normal inversion agitation times by pre-soaking the films and gets the same level of development. His belief is that pre-soaking exactly makes up for the extra development that constant agitation provides.

He quotes 3 films( Ilford Pan F;FP4+ and D400) and three developers(ID11; Perceptol and Microphen). His pre-soak is 5 mins

Of course you need to have faith that his results are accurate and can be replicated but I suspect they are. If he is right it avoids experimentation with new times at least for these developers and films

pentaxuser

 

[ic-racer]

Not useless. Just may not answer a density question you have.

I'm curious, what criteria, besides negative density, would you use to evaluate different agitations protocols?

 

[Andrew O'Neill]

In the past I have done constant agitation with BTZS tubes with very dilute developer and HP5-Plus and got interesting results, tonally speaking as well as slight increase in speed. I gave it up because one gets quite tired spinning a tube by hand for 20-25 minutes.
I read somewhere (might have been Phil Davis) that modern films with T grain emulsions need more agitation than conventional films... or was it more vigorous agitation?

 

[polyglot]

OK, when going from times that are based around a agitate/sit routine, what is the rule of thumb in time reduction when doing constant agitation? BVY suggested 20% on page one. Is this, though, a 'starting point' only and a case of mileage varying?

The reduction in time required depends on the developer you use; some (like dilute Rodinal) are very sensitive to agitation changes while some (Xtol) are quite insensitive to agitation changes. There's also the matter of pre-soaking which is often recommended for rotary development and a (very rough and it probably only applies to Xtol) rule of thumb is that if you pre-soak then develop with continuous agitation for the intermittent-agitation time, you will get about the right result, i.e. they roughly cancel for "normal" development times. A pre-soak has a greater effect when your development time is short. If you have a diffusion enlarger, you probably wouldn't mind some extra contrast so go right ahead and use the intermittent time for continuous agitation with no presoak; you might like it better.

While I agree with you in principle, ic-racer, for most people that level of precision is not important. "Can I print my negs reliably" is all that really matters I think, and that's a pretty low bar these days with access to decent VC papers. My experience with my CPP2 is that any speed between 3 (30RPM?) and P (90RPM?) will give indistinguishable results, and that's kind of what I'd expect because even at the lowest speed, there is always movement, always a good degree of mixing and always fresh developer presented to the emulsion surface. I would expect to see much greater differences from temperature- and timing-carelessness than even a 3x change in rotation speed.

 

[piu58]

> I'm curious, what criteria, besides negative density, would you use to evaluate different agitations protocols?

More agitation reduces problems with cloudy sky and other even areas.

 

[hoffy]

> I'm curious, what criteria, besides negative density, would you use to evaluate different agitations protocols?

More agitation reduces problems with cloudy sky and other even areas.

Interesting.... I never knew that.

 

[swmcl]

Hoffy,

I can confirm that 1:50 Rodinal in an Expert drum being rotated at around 6rpm (10 secs per revolution) by hand leads to 6 busted sheets of film ! Uneven development. My hunch is that Rodinal needs to be more concentrated (eg. 1:25) when used in a constant agitation setup. I am not willing to increase rotation / agitation as I think 6 rpm is more than enough. Certain developers are more sensitive than others to agitation. At 1:50 I think it is in the realm of semi-stand development which I cannot achieve with my equipment.

Yes I am being anal with a densitometer ...

Cheers,

Steve

 

[mrred]

I would have thought Rodinal would have been the worst developer of choice, for constant agitation (in drums).......just because of the grain. However if streaking is the issue, pre-soak the film in a bit of photoflo. It will make the developer uniform during the development.

 

[Trask]

It seems that this discussion is only addressing rotation as the means of constant agitation -- and with rotation comes, I imagine, increased mixing of air and developer so increased oxidation. There is an alternative, perhaps -- vibration. In the old days there was the Vokar Film Tank Agitator (picture attached) which attached a vibrator unit to the tank, then plugged into 110V. Sounds like a suicide device to me, but LPL in Japan made much more recently a vibration platform that the tank simply sat on and was vibrated, presumably with a constant-frequency buzz. No air-developer mixing, but also no complete flushing of exhausted developer from the film surface itself. Perhaps the idea with the LPL is to lift the tank off the agitator every minute, invert once, then return to the agitator. I'd be curious of anyone has experience with agitation of this sort -- heck, I guess you could set the tank on the clothes dryer as a start.