Cinestill DF96 monobath

Huss · Apr 23, 2020

A gentleman on RFF tipped me to filter the DF96 before I try to use it again, and then check with a test piece of film to see if it is still ok.
Using a paper coffee filter, it removed sludge from the solution! Guess that was the emulsion stripped off the Silberra film, The dev was now clear again, the test strip was fine so I went ahead and developed a roll of TriX normally.
All ok.
I appreciated the tip to filter it, I would not have thought of that.

Raghu Kuvempunagar · Apr 24, 2020

Anon Ymous said:
A monobath is a balancing act. You have two different processes running parallelly, development and fixation.

Also reusing the monobath without any replenishment makes it even more complicated. I would imagine that the developer and fixer are depleted at different rates.

Donald Qualls · Apr 24, 2020

Not by much. Unreplenished D-76 stock, as I recall, with extended development on a per-roll basis, is good for more than a dozen to perhaps twenty rolls from a liter, and full strength fixer is good for more than a dozen for certain. The depletion rate is probably adjustable by adjusting the level of thiolsulfate in the monobath.

Replenishing a monobath hadn't even occurred to me, but now I think of it, C-41 fixer use replenishment in automatic machines. No good reason one couldn't replenish monobath. If you made one using a developer that is its own replenisher (Xtol, say), it might be a fine way to proceed.

Raghu Kuvempunagar · Apr 24, 2020

Donald Qualls said:
with extended development on a per-roll basis,

Extended time in monobath would make sense only if both developer and fixer deplete at the same rate. If the developer depletes much faster than the fixer, we can't use extended time in monobath to compensate for it as the fixer will remove the halides resulting in underdeveloped negatives. Otoh if the fixer depletes much faster than the developer, then extended time will result in over development.

It's possible that the monobath is loaded with the developer and fixer and they don't really get depleted much for the advertised capacity. So extended time is not needed.

Donald Qualls · Apr 24, 2020

Cinestill does, however, recommend exactly that -- add 30 seconds for each roll (135-36, 120, or 8x10 sheet equivalent) previously processed. That tells me that apparently they've tuned the developer to fixer ratio to give the same depletion rate, since the other time adjustment they recommend (double time for tabular grain films) is explicitly because those films fix slowly compared to cubic grain.

Huss · Apr 24, 2020

Donald Qualls said:
Cinestill does, however, recommend exactly that -- add 30 seconds for each roll (135-36, 120, or 8x10 sheet equivalent) previously processed. That tells me that apparently they've tuned the developer to fixer ratio to give the same depletion rate, since the other time adjustment they recommend (double time for tabular grain films) is explicitly because those films fix slowly compared to cubic grain.

It is 15 seconds:

CHEMICAL REUSE:

Can process 16+ rolls of film. Simply recombine used chemistry and add +15sec. for each roll previously processed until you reach 8 min. If a film does not appear fully cleared, process for longer in Df96. It will not affect development.

Dj cooler martin · Apr 24, 2020

Donald Qualls said:
Best keep your Orta 50 out of Caffenol, too, then, if that's the cause

And out of pyro

Donald Qualls · Apr 24, 2020

Huss said:
It is 15 seconds:

CHEMICAL REUSE:

Can process 16+ rolls of film. Simply recombine used chemistry and add +15sec. for each roll previously processed until you reach 8 min. If a film does not appear fully cleared, process for longer in Df96. It will not affect development.

Woops, you're right. Still, if the developer were depleting faster than the fixer, you'd get progressive loss of true speed as the monobath "wears down", where if it were the other way, you'd see a slight increase.

The other way they might get around this is to formulate the developer to develop to completion, and do so much faster than the fixing time -- but I doubt they're doing that, as that wouldn't permit us to adjust contrast (push and pull) by adjusting temperature and agitation, as the instructions suggest (higher temperature w/ limited agitation gives more development = higher contrast = "push", more agitation at lower temperature gives faster fixing = lower contrast = "pull").

Raghu Kuvempunagar · Apr 25, 2020

Huss said:
It is 15 seconds:

CHEMICAL REUSE:

Can process 16+ rolls of film. Simply recombine used chemistry and add +15sec. for each roll previously processed until you reach 8 min. If a film does not appear fully cleared, process for longer in Df96. It will not affect development.

Is it recommended to filter the monobath solution after every use?

Huss · Apr 25, 2020

Raghu Kuvempunagar said:
Is it recommended to filter the monobath solution after every use?

No. I only did it to remove the emulsion that was stripped off the Silberra film thanks to the advice from another gentleman.
That emulsion was floating around in fine chunks in the developer. Filtering it removed it. I have since developed three more rolls of film with no issues, and the DF96 is clear as before.

Donald Qualls · Apr 25, 2020

I agree. Normally, all you need to do is pour the Df96 back into the bottle after your process time expires, and make a mark or otherwise tally the count of processed rolls so you know how much time to add the next time you process with it.

Black and white film will never be any easier than this. Yes, you're giving up some of the subtleties (like eking out the last 1/3 stop of true film speed with a different developer, and extended time with reduced agitation to control contrast, or making the same film look like coarse sandpaper for one shoot and produce smooth, creamy tones for another by changing EI, developer, and process method) -- but "bring up to temp, pour it in, start the timer, agitate as directed, pour out, wash" won't ever get easier.

Raghu Kuvempunagar · Apr 25, 2020

Donald Qualls said:
Replenishing a monobath hadn't even occurred to me, but now I think of it, C-41 fixer use replenishment in automatic machines. No good reason one couldn't replenish monobath. If you made one using a developer that is its own replenisher (Xtol, say), it might be a fine way to proceed.

The easiest thing to try in the context of DF96 would be to use DF96 itself as its replenisher. Might not be the best replenisher but would it be any worse than unreplenished DF96? It may even make the extra 15 seconds of development needed after every use unnecessary.

Donald Qualls · Apr 26, 2020

Raghu Kuvempunagar said:
The easiest thing to try in the context of DF96 would be to use DF96 itself as its replenisher. Might not be the best replenisher but would it be any worse than unreplenished DF96? It may even make the extra 15 seconds of development needed after every use unnecessary.

I found a formula for D96R Replenisher in Kodak publication "Processing KODAK Motion Picture Films, Module 15: Processing Black-and-White Films" (dated 2000). The question in my mind is how to replenish the fixer component, to maintain the same ratio between fixing and development (critical to getting correct film speed), as well as deal with silver buildup in the monobath (with replenished fixer in C-41 machine operation, you reach a floating level, recover silver from waste discharge -- a fixed amount each cycle -- and replenish what's left).

It appears that Kodak, at least, used Flexicolor fixer as its own replenisher, so it seems possible one might be able to add a little phenidone, hydroquinone, and sulfite to Df96 and use it as its own replenisher, but then there's the question of how much to replenish, and whether that matches required replenishment rates for developer and fixer at the same time. If I processed enough film to seriously consider this practice, I'd probably want to replenish separately for the developer and fixer components in order to keep both at the correct strength.

That said, I have no doubt it would be possible to design a monobath for replenishment -- but replenishment is something you'd normally only do in a volume lab, which is not the niche monobaths are made for. Monobaths are aimed at folks for whom only storing one or two bottles of chemicals (Monobath plus a bottle of mixed Photoflo equivalent) makes home processing possible, or at processing on the road (they used to be a photojournalist's way of knowing he didn't have to reshoot while still on location). They aren't really intended for a permanent lab that processes more than a few films a week, where individual control of each process has the potential to give improved results.

Huss · Apr 29, 2020

Frank and Sonny at the Alfa shop.

Nikon F4, 28-105, Arista 400, Cinestill DF96 Monobath.

Raghu Kuvempunagar · Apr 30, 2020

Huss said:
Cinestill DF96 Monobath.

Nice!

On Facebook I saw someone posting his paper negatives developed with this monobath. His results were pretty good.

Donald Qualls · Apr 30, 2020

Raghu Kuvempunagar said:
Nice!

On Facebook I saw someone posting his paper negatives developed with this monobath. His results were pretty good.

Really! Any idea what temperature and agitation they're using?

Raghu Kuvempunagar · Apr 30, 2020

Donald Qualls said:
Really! Any idea what temperature and agitation they're using?

35 seconds in the monobath at room temperature.

http://www.facebook.com/groups/1438777439673554?view=permalink&id=3267862996764980

laingsoft · Apr 30, 2020

Donald Qualls said:
That said, I have no doubt it would be possible to design a monobath for replenishment -- but replenishment is something you'd normally only do in a volume lab, which is not the niche monobaths are made for. Monobaths are aimed at folks for whom only storing one or two bottles of chemicals (Monobath plus a bottle of mixed Photoflo equivalent) makes home processing possible, or at processing on the road (they used to be a photojournalist's way of knowing he didn't have to reshoot while still on location). They aren't really intended for a permanent lab that processes more than a few films a week, where individual control of each process has the potential to give improved results.

Depending on how advanced a person is, you might be able to do a HQ developer and replenish it by titrating KI and then adjusting the PH back up to where it needs to be. How you'd make that user friendly for the home gamer would be tricky though.

Donald Qualls · Apr 30, 2020

laingsoft said:
Depending on how advanced a person is, you might be able to do a HQ developer and replenish it by titrating KI and then adjusting the PH back up to where it needs to be. How you'd make that user friendly for the home gamer would be tricky though.

I don't think a monobath aimed at home use (like Df96) will be successful with replenishment in any process more complex than "replenish with X ml of replenisher per roll processed, discarding used solution beforehand if needed to maintain working solution volume." That's the way replenished D-76 and D-23 work, as well as some dilutions of HC-110 (and C-41 for commercial mini-labs). Easy enough for home operators -- except home operators are very unlikely to process enough film in any of those developers for replenishment to make sense vs. one-shot with higher dilution. With a monobath in a one quart or one liter batch size, it might make sense for an avid shooter who uses a film that works well in the chosen monobath.

If you're advanced enough to do titration with your photo chemicals, there's no reason you'd consider replenishing a monobath from Famous Format or Cinestill; you'll have a dip-and-dunk line with conventional developer on replenishment (using C-41 fixer with its replenishment schedule, maybe), or you'd be too time-bound to bother, vs. use it up and toss it, and open another jug.

Huss · Apr 30, 2020

Zeiss Ikon Nettar, Delta 400, DF96 Monobath

Donald Qualls · Apr 30, 2020

Well, if you put it that way...

Mamiya RB67 ProS, 90 mm Sekor C, long-expired .EDU Ultra (aka Fomapan) 100 in Df96:

Raghu Kuvempunagar · Apr 30, 2020

laingsoft said:
Depending on how advanced a person is, you might be able to do a HQ developer and replenish it by titrating KI and then adjusting the PH back up to where it needs to be. How you'd make that user friendly for the home gamer would be tricky though.

Main motivation to think about replenishment in the context of DF96 is to get consistent results everytime one uses it without having to adjust processing time.

Nice to see some examples of DF96 processing. Keep them coming.

Huss · May 1, 2020

Nikon F4, 28-105, Arista 400, DF96 monobath

Donald Qualls · May 1, 2020

Raghu Kuvempunagar said:
Main motivation to think about replenishment in the context of DF96 is to get consistent results everytime one uses it without having to adjust processing time.

But I can do that very easily, with conventional one-shot diluted developers -- D-76 1+1 or 1+2, Xtol 1+1 or 1+2, D-23 1+1, HC-110 Dilution G or H, D-72/Dektol 1+9, Parodinal at any dilution, etc. Replenishment enters the equation when you want/need the faster process of stock solution (D-76, D-23, Xtol) or lower dilution (HC-110 A or B), along with the economy of getting full use out of your developer. Monobaths aren't really in either category -- diluting Df96 would slow the developer more than the fixer (most likely) and result in significant loss of speed or require raising temperature significantly. Replenishing it might be a useful approach, but someone would have to work out the correct rates for the developer and fixer components and make a replenisher that can be handled by simply dosing per roll processed, and I'm fairly certain that the monobath itself isn't the right stuff for that (as witness the significantly different formula for D-96R vs. D-96).

Huss · May 6, 2020

Nikon FM, 43-86 v2, Kentmere 400, Cinestill DF96 Monobath

Cinestill DF96 monobath

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