C-41 flexicolor capacity with Jobo 1520 Tank

I’m sure there’s an answer to this floating around here, but I’ve been searching for a couple days and can’t seem to find a definitive answer.

I recently acquired a Jobo Duolab. It came with a 1510 tank, a 1520 tank, and a 1530 extender. Before this I was all Paterson tanks.

For BW at 24C, the Duolab has been wonderful. I use replenished XTOL with it and and use 150ml and 270ml with the 1510 & 1520 each and the output has been excellent.

I’ve not yet run any C-41 with it yet because I have some concerns: since switching over to real flexicolor chemicals a while back, I’ve always followed the Z-131 manual and done 3 135 rolls or 2 120 rolls, or 4-6 4x5 sheets per liter of developer working solution as one-shot, and aside from some initial shake down, that has been *very* consistent. I have very little interest in trying to get as much capacity as possible from my chems so just go with a minimum of 333ml per 80 square inches of film in Paterson tanks and would rather keep it simple and consistent if possible.

With the 1510 tank, I doubt C-41 would work at all as the tank is just too small.

With the 1520 tank, I did a test run with 333ml of water (which does fit into the water jacket bottle) and it overflows from the tank back into the bottle once rotating on the Duolab (the water jacket bottle stays screwed onto the Duolab cog).

Erm, OK. Not what I was hoping for. The water jacket bottle has markings for 140 and 270ml.

My question is can I safely drop my minimum solution down to something that will fit into the 1520 tank and maintain consistency? According to Z-131, some films are fine with 250ml per 80 square inches. I have a hard time believing that would be OK for everything though. 270ml? That seems more reasonable, though now I’m into an odd per liter thing, though I can manage that.

Surely C-41 has been being consistently done with a 1520 tank one shot with all film speeds for 35mm and 120, so what’s the best practice here? I’m using the flexicolor LU/Lorr developer with starter.

With my CPE2 Jobo, I have used the 1510, 1520 and 1540 tanks with C41 very successfully.

Things may be different with what you are using, but essentially I worked on 8 x 36 frame rolls per litre of C41 and just worked out what was needed to do whatever, using the capacity of the developer solution to the best advantage.

The 1540 tank is the most efficient way to use C41 chemistry, 500ml (effectively) per each 4 roll session.

The 1510 tank with the 1530 extender, is the 1540 tank.

But to specifically answer your 1520 question, I used that tank quite a lot for either 2 x 36 rolls or 2 x 120 rolls.

Mick.

Page 3-5 of the current, Kodak Alaris version of Z-131 seems to indicate capacity numbers greater than your post - 4 x 135-36 or 3 x 120 or 10 x 4x5 sheets per litre: http://imaging.kodakalaris.com/sites/uat/files/wysiwyg/pro/chemistry/z131.pdf
The older version of Z-131-3 on 125.px is consistent with that.

Matt, were you talking to me or Mick?

I essentially follow the 120 guidance as my per roll minimum, which is 3 rolls per liter, or 333ml per roll. If doing 1 120 roll in a Paterson tank, I use 500ml, or 2 120 rolls I use the whole liter. If doing 135, I put 3 rolls in and use a whole liter. Mod54 is either 4 or 6 sheets and a whole liter.

Mick, not saying you’re wrong, but 125ml per roll doesn’t sound like enough. Much like D76, you can use less than 250ml of stock D76 per roll, but if you want consistency, use at least that much.

Adrian, 1 litre divided by 8 = 125ml.

It certainly sounds miniscule, but 4 rolls in 500ml doesn't sound miniscule, 8 rolls in a litre and so on.

Rotary processing is a whole new ball game, mostly better.

Mick.

Mick Fagan said:

Adrian, 1 litre divided by 8 = 125ml.

It certainly sounds miniscule, but 4 rolls in 500ml doesn't sound miniscule, 8 rolls in a litre and so on.

Rotary processing is a whole new ball game, mostly better.

Mick.

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Again, not saying you're wrong as I have essentially no JOBO experience to back anything up, but even if I was doing D-76 with BW in a JOBO I'd still use a minimum of 250ml stock per 80 square inches of film as per my experience, that really is the minimum for D76 if you want consistency no matter what. For a fair number of images, less than 250ml D76 would be fine, but, there are also a fair number (super dense negative, etc) where less than that would be a disaster resulting in less than consistent images. To me, it's not worth it to try to save a couple of pennies of developer on an image that I potentially spent hours getting.

Truth be told, I've never paid much mind to C-41 minimum per roll requirements for complete and consistent development because even if doing 1 135-36 roll in a paterson tank, you have to put at least 290ml in the tank just to cover the film, and 500ml for 1 120 roll even though both have essentially the same surface area. Using 333ml minimum per roll no matter the roll type was a simple convenience because the 1L paterson tank only takes 3 135 rolls or 2 120 rolls and it was simple to just do either 3 135 or 2 120 rolls at a time and use a whole liter. Same for the Mod54 for sheet film.

It's clear to me that the "real" minimum is less than what I've been using for C-41 in Paterson tanks and I'm OK with that, I just have a really difficult time being comfortable that 140ml in a 1510 tank is enough developer to ensure complete and consistent development even with 100 ektar, 160 portra, 400 portra, or 800 portra.

What is the replenisment rate per film for the developer you use? Should be somewhere on the bottle/box or in the Kodak literature. This gives you an approximate idea of how much chemistry is really used when developing a roll. In my limited experience, the typical replenishment rates in C-41 are considerably less than 100 ml per roll. I think Mick is right and you are worrying too much.

mnemosyne said:

What is the replenisment rate per film for the developer you use? Should be somewhere on the bottle/box or in the Kodak literature. This gives you an approximate idea of how much chemistry is really used when developing a roll. In my limited experience, the typical replenishment rates in C-41 are considerably less than 100 ml per roll. I think Mick is right and you are worrying too much.

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I hope I am worrying too much. I don’t have the replenished numbers off the top of my head, however Kodak does list capacity for unreplenished systems in Z-131. For slower films they list 4 rolls per liter and 3 rolls per liter for 120 and faster films. That comes out to 250-333 ml per roll, which I realize is probably a very safe conservative, though the 125 ml that Mick uses feels awfully thin, though at the same time I can’t imagine Jobo making a processor that didn’t let you put enough developer in to handle correctly processing c41 without a bunch of people yelling and screaming about it.

I guess the only way to find out is run some test rolls or spend some coin on some control strips.

Adrian Bacon said:

Matt, were you talking to me or Mick?

I essentially follow the 120 guidance as my per roll minimum, which is 3 rolls per liter, or 333ml per roll. If doing 1 120 roll in a Paterson tank, I use 500ml, or 2 120 rolls I use the whole liter. If doing 135, I put 3 rolls in and use a whole liter. Mod54 is either 4 or 6 sheets and a whole liter.

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I was talking to you Adrian. What confused me was your reference in your first post in the thread where you said: "I’ve always followed the Z-131 manual and done 3 135 rolls or 2 120 rolls, or 4-6 4x5 sheets per liter of developer working solution as one-shot,"
That is different than the 333 ml per litre (for 120) that you refer to later.

mnemosyne said:

What is the replenishment rate per film for the developer you use?

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Z-131 refers to a number of different replenishment rates, depending on the process equipment used and whether you are using C-41 or C-41 LORR developer replenisher.
In Z-131, for 120 rolls, the replenishment rate varies from 20 ml/roll in minilab machines to 72 ml/roll in sink line processing..

Matt, sorry for the confusion, I should have been clearer that I was using the 120 per roll guidance for the per roll minimum in my first post. It’s been a long week already and it’s only Monday. Got multiple fire drills happening today.

All that being said, there’s what Kodak’s doc says and what’s happening in practice with jobo users. In Kodak’s D76 tech sheet they guide 250ml stock per 80 square inches and that really is about right, so that makes me think the current Z-131 volumes has some weight.

Nobody so far has cautioned against Mick’s numbers so I’m inclined to shoot some test rolls and run them through the Duolab using the minimums marked on the tank, then do the same thing but jam as much developer in the tank as it will take and look at the differences between the two runs. Since higher speed films seem to require more developer I’ll do it with portra 400 in 135 format to try to exaggerate any differences that show up. It’ll be 1 roll in the 1510 tank and 140ml, then 1 roll in the 1520 tank with ~333ml in the tank. Some of it will spill out, so it’s probably 300ml or so, but either way, more than double the developer of the first roll.

Adrian Bacon said:

All that being said, there’s what Kodak’s doc says and what’s happening in practice with jobo users. In Kodak’s D76 tech sheet they guide 250ml stock per 80 square inches and that really is about right, so that makes me think the current Z-131 volumes has some weight.

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Adrian:
I don't think you can glean anything relevant from a comparison with D-76, because the capacity behaviour of D-76 is particular to D-76.
To pick an example for comparison, HC-110 developer has different capacities for different dilutions. Whatever dilution you use, if there is at least 6 ml/roll of concentrate in the tank, it will have enough capacity.

My replenishment target is approximately 70 ml/roll of both 120 and 35mm. By my calculations, Kodak recommends 36.1 ml/roll. 65 ml/ft^2 is the reference Kodak number that I am using.

I plan to lower replenishment rate gradually to the 50 ml/roll level, while keeping an eye on quality, and will intentionally maintain a greater (more conservative) replenishment rate than Kodak's figures.

I use the rotational volumes listed on the side of the tanks and drum and I have not ever had a problem from lack of chemicals.