C-41 and E-6. Minimal chemistry volume for JOBO tanks?

[Steven Lee]

This has been asked before, I found some old threads but the suggestions were all over the map. Here's the problem:

• Minimal chemistry volumes recommended by JOBO are provided with the clearly stated caveat: these are just volumes required to cover the film, they do not guarantee to meet chemistry manufacturer's minimal volume requirements.
• Chemistry manufacturers do not always list minimal volumes, and old Kodak PDFs tend to be overly conservative.

Kodak's Z-131 says 3-4 rolls per 1L for C-41. Their J-83 says the same thing for E-6. Numerous photrio threads suggest that these estimates are overly conservative or not applicable to rotary processing.

Specifically, I want to develop 4 rolls of 120 film using 500ml in a JOBO tank for both E-6 and C-41. My Bellini E-6 kit does not list minimal volume requirements, the instructions are written for reusing chems. I do not want to reuse color developers, I want to split 1L bottle into two 500ml batches for 4 rolls each. For C-41 I am using Flexicolor LORR.

Has anyone done this? Thanks.

 

[eradman]

I'd say you are figuring this correctly. (500 ml to develop 4 rolls)

Looking at the Arista E-6 instructions we can see that the number of rolls you can process corresponds with the amount of developer

-	135 (24 exp.)	135 (36 exp.)	120
Rolls / 960ml (32 oz)	12	8	8
Rolls / 480ml (16 oz)	6	4	4
Rolls / 240 ml (8 oz)	3	2	2

 

[Mick Fagan]

The 1510 tank, plus the 1530 extender allows for 4 rolls of 135 film using 4 reels, or 4 rolls of 120 film using 2 reels, and 500ml of solution. About 470ml is the actual requirement from memory, but I always just used 500ml.

This is using two of the 1500 reels in the 120 film width position and using the little red press button thingy to maintain separation between both 120 rolls.

Doing two 120 rolls on a single reel is slightly fiddly, but very doable.

 

[Scott J.]

My standard volume for E-6 and C-41 (Flexicolor LORR) in the Jobo 2500 tank is the volume recommended by Jobo to cover the film -- 270 mL. This is for either two rolls of 135-36 (on two separate reels) or two rolls of 120 spooled onto one reel. Doubling that for four rolls (4 x 80 in2) works out to 540 mL, but I'm quite confident you'd be fine from a capacity standpoint with 500 mL. The limiting factor in color development is different from that in black and white, largely due to the fact that standard dilution color chemistry appears to have much higher capacity. In other words, if you have enough E-6 or C-41 chemistry in the tank to physically cover the film, you've got more than enough chemical capacity to develop the latent image. With black and white, that's sometimes not the case (e.g., dilute developers like Xtol 1+3, Rodinal 1+99, etc.), where you can physically cover the film but still not have enough capacity to develop the image.

The 1510 tank, plus the 1530 extender allows for 4 rolls of 135 film using 4 reels, or 4 rolls of 120 film using 2 reels, and 500ml of solution. About 470ml is the actual requirement from memory, but I always just used 500ml.

I checked my notes and the above is true. Using the Jobo 1540 module (a 1510 tank + 1530 extender) requires 470 mL of solution to cover film all the way to the inner track of a reel. So for four rolls of 120, you'd need two 1500 reels loaded two rolls of 120 each. In fact, now that I think about it, I'm pretty sure I've used this exact combination with 470 mL of color chemistry before and not had a problem. I just tend to prefer the 2500 tanks and reels and so use them more often.

 

[Steven Lee]

@Scott J. @Mick Fagan @eradman Thank you!!!!

 

[PittP]

Above notes are correct.
The Tetenal E6 instructions suggest that, one film requires 83 ml of solution (1+4 standard dilution). This amount would be exhausted after developing one roll of 135-36 or equivalent.
I've once tried to reuse this chemistry for a 2nd run with extended times, and the results were not so good, notably slight colour shifts and poor blix.

 

[mshchem]

A Jobo 1520 tank will hold 2 120 films on one reel, this requires 240-250mL of fresh chemistry (C-41 or E6 or undiluted B+W) I have never had a problem. Same thing with 4 120 (480-500mL) films in a Jobo 1540. In either case use fresh unused chemistry.
These reel tank combinations were designed to accept 220 film, which is just double length of 120.

If you want to reuse or replenish the used solutions I would use care. Also storing the used solutions can be an issue.

Use a Jobo processor, per instructions.

 

[Steven Lee]

As I'm keeping an eye on this thread, I am also googling, trying to find out the reason for such conservative capacity statements in Kodak PDFs. Three possible explanations I found earlier today are:

1. Older films had thicker emulsion using more silver and requiring more chemicals
2. Instructions are written for the worst case scenario, i.e. bright scenes for each frame on a roll (or even 100% dmax coverage)
3. The chemistry has been reformulated, notably their LORR developer having greater capacity

And yes indeed, JOBO 1540 is what I'm using. Two reels with two 120 rolls on each.

 

[MattKing]

Most likely reason #2.
I have no problem with people saying that the capacity recommendations are conservative if those same people are running control strips and keeping everything within tight tolerances.
I expect though that most of those observations are coming from people whose process controls aren't quite that rigorous.

 

[Steven Lee]

@MattKing you are right, I am very much hoping for someone who runs control strips to confirm that 500ml of fresh C41 or E6 per 4 rolls develops within spec.

 

[MattKing]

@MattKing you are right, I am very much hoping for someone who runs control strips to confirm that 500ml of fresh C41 or E6 per 4 rolls develops within spec.

Remember - if the capacity recommendations are conservative in order to protect with respect to a high percentage of films that record a lot of bright scenes, you would need that someone to run a decently large number and variety of film before you could rely on their tests.
All those modern influencers who recommend shooting Portra 160 at an EI of 80 and taking lots of photos of brides in white dresses down amongst the surf are probably testing the recommendations regularly

 

[Scott J.]

I run control strips in my Jobo for both E-6 and C-41, but primarily as a check on chemistry stability over time (sometimes I'll go several weeks without developing film and want to make sure that my concentrates or working solutions are still in good shape prior to using them on rolls or sheets). I suspect this is the objective that most home users have in mind if they periodically run control strips. But what Matt says is also good advice -- i.e., run a control strip with other film to test capacity. The Jobo system isn't particularly well suited to that application, as it may require some creativity to overcome mixing different film formats. In the case of the 1540 module with four rolls of 120 film, I suppose one could perhaps affix the control strip to the inside wall of the tank, or maybe even just let it float freely in the tank and hope it doesn't scratch the other films.

Curious to hear some suggestions on how to approach this.

 

[Steven Lee]

@Scott J. Thank you. I am looking into control strips, and my understanding is that I must purchase a decent color densitometer as well, and after checking eBay listings it appears to be around $1K investment, is that accurate? I also considered not buying a densitometer and figuring out a way to evaluate control strips by scanning them, but this requires at least borrowing a densitometer to calibrate the DIY setup.

 

[Scott J.]

@Scott J. Thank you. I am looking into control strips, and my understanding is that I must purchase a decent color densitometer as well, and after checking eBay listings it appears to be around $1K investment, is that accurate? I also considered not buying a densitometer and figuring out a way to evaluate control strips by scanning them, but this requires at least borrowing a densitometer to calibrate the DIY setup.

Yeah, the prices on them are completely bonkers. I was fortunate to have come across an X-Rite 811 a couple years ago that got sold for $125 because the owner thought it was broken. I was pretty sure I could repair it, but when I received it I discovered the transmission lamp was simply not seated in the socket. It worked perfectly and even came with the original calibration strip (which is another thing you really need to have to run the machine properly, and the ones selling on the used market often don't have them).

Where are you located? Do you have control strips already? There might be a lab in your area that would be willing to run your strips for you, which would at least save you the cost of buying a color densitometer. If you already have control strips and were looking to run a few to test out the scenarios discussed above, I'd be happy to measure and plot the results for you. You could just mail them to me along with the reference strip that came with the box.

 

[Radost]

This has been asked before, I found some old threads but the suggestions were all over the map. Here's the problem:

• Minimal chemistry volumes recommended by JOBO are provided with the clearly stated caveat: these are just volumes required to cover the film, they do not guarantee to meet chemistry manufacturer's minimal volume requirements.
• Chemistry manufacturers do not always list minimal volumes, and old Kodak PDFs tend to be overly conservative.

Kodak's Z-131 says 3-4 rolls per 1L for C-41. Their J-83 says the same thing for E-6. Numerous photrio threads suggest that these estimates are overly conservative or not applicable to rotary processing.

Specifically, I want to develop 4 rolls of 120 film using 500ml in a JOBO tank for both E-6 and C-41. My Bellini E-6 kit does not list minimal volume requirements, the instructions are written for reusing chems. I do not want to reuse color developers, I want to split 1L bottle into two 500ml batches for 4 rolls each. For C-41 I am using Flexicolor LORR.

Has anyone done this? Thanks.

PE posted back in the day a number of 6 rolls per pint which is around 12 for a liter. All with development time extension. Pretty standard C41 estimation.
Never had a Jobo but I guess using less chemistry oxidizes more and forces it to be one shot.

 

[Radost]

I did a screen shot

 

[Steven Lee]

@Scott J. Thank you for the offer! No I do not have the strips yet, but if I decide to jump into this I will probably just get a densitometer as well.

 

[Scott J.]

@Scott J. Thank you for the offer! No I do not have the strips yet, but if I decide to jump into this I will probably just get a densitometer as well.

They really are handy machines to have if you can find one. It'll eliminate any worry you have about whether your chemistry, which may have sat unused for a long time, is any good. My experience has been that the Kodak Flexicolor chemistry is extremely shelf-stable. The replenisher developer solution will keep for many months in a sealed glass jar, and I've even had working-strength developer produce in-control control strips after sitting in a partially filled glass bottle for >4 months (for what it's worth, I usually blanket with Protectan spray).

The same goes for the Fuji-Hunt E-6 chemistry (which sadly has disappeared in the 5-liter kits). I always decanted the concentrates into smaller glass bottles to reduce their exposure to air (e.g., by dividing the contents of a 1-liter plastic container that came with the kit into four separate 250-mL glass bottles with caps). By doing this, the concentrates would produce in-control control strips even after >1 year. (Full disclosure: I mix my E-6 chemistry working solutions on an as-needed basis, as opposed to mixing the entire kit into working solutions all at once.)

Be aware that if you want a densitometer that can do both negative films and positive films, you'll need one that can read Status M (for color and B&W negatives) as well as Status A (for color positives). For example, the X-Rite 810 is a color densitometer, but it can only read Status M (good for negatives only, be they color or black and white). By comparison, the X-Rite 811 is basically a "souped up" version of the 810, in that it does everything the 810 does plus it has Status A read capability, therefore meaning it can read color positive film. Manuals for both machines can be found here: https://www.film-and-darkroom-user.org.uk/forum/showthread.php?t=6215

Good luck!

 

[Steven Lee]

@Scott J. That's useful advice, thank you!