Does doubling 120 film on a reel mean more developer, too?

bags27 · Apr 22, 2022

Hi all,

Lurked for a long time. Recently decided to give Barry Thornton's 2-bath a try (just ordered the chemistry from Bostick & Sullivan), and read David Allen's entries on it, and pretty soon read every David Allen entry on everything and then pretty much everyone else's entries on everything for the past decade. I'm told I'll soon be released after I convince just one more psychiatrist.....

One of the many things I learned is that you can double up 120 film on a reel. Of course. Duh! But just wondering if it affects the chemistry. After all, the total exposed surface of 2 120 rolls is going to be more than the surface even of a roll of 135 film. Has anyone noticed a difference between using one or two strips/reel? I suppose it shouldn't affect a compensating developer much, but still it creates a pretty significant variable in a process for which optimally we eliminate variables.

Thanks so you all for so many incredible conversations (and debates) on this thread. It's a treasure trove for me.

Sirius Glass · Apr 22, 2022

The film has to be covered and with my tanks they are. That said I use 500ml of developer in my tanks and the chemicals go back into the container. It is rarely worth counting every ml of solutions.

grahamp · Apr 22, 2022

With inversion agitation you need a) enough solution to completely immerse the reel, and b) enough developing agent to handle the film area. Both these conditions need to be true for the time, temperature, and dilution of the developer you choose.

1 x 35mm(36 exp) = 1 x 120 = 4 x (4x5) = 1 x (8x10) for practical purposes.

Thornton gave between 10 and 15 rolls of film per litre as the capacity of TTB. I think carry over losses with my equipment reduce the stock volume a lot, so I tend to work on 10 rolls/litre equivalent. So that's 100ml of stock per roll.

Using those numbers, you need at least 200ml of part A for 2 x 120. So your tank/reel volume dictates how much stock you need. Use the same volume of part B.

If you want to use a rotary system like a Jobo, then you have to factor both the minimum and maximum solution volumes for the tank in use.

MattKing · Apr 22, 2022

What grahamp said.
And to reinforce - two 120 rolls require the same amount as two 135-36 rolls - about the same surface area,
grahamp's analysis for Thornton 2 bath is the way to approach the issue. Don't forget to apply it as well to capacity questions.
You are more likely to run into problems if you are using more dilute developers like D-76 1 + 1 or HC110 dil H.

bags27 · Apr 22, 2022

Thanks all! Appreciate the responses.

I use a Patterson canister that holds 3 135 or 2 120 reels. For one 120 reel, I use 500 ml of developer, for 2 reels 1000ml (with one MF roll/reel). I just thought if I double up to 4 120 rolls/canister I'd put a heavier demand on my developer. I doubt it would affect (say) Pyrocat HD at 1:100 or HC110 at semi-stand solution, but I sometimes use DDX (for t-grain), and I know that's a developer that's more proportion-sensitive. So, just wondered....

MattKing · Apr 22, 2022

It is actually a good thing to wonder about.
It seems, however, that what matters most is the concentration of developer - provided there is enough in the tank to develop at least as much film as you are adding to the tank.
If you have working strength developer to work with, it doesn't seem to matter if you develop in 1/2 litre, one litre or two litres of that developer - the results will be essentially the same, provided that there was enough developer in the 1/2 litre to do the job.
Of course, if you are re-using developer, there will be much less capacity left in the 1/2 litre of partially used developer, than there will be left in the larger volumes.

Donald Qualls · Apr 25, 2022

If you're running a high dilution, doubling the film area may require using a stronger solution or more volume than the minimum needed to cover the film (for instance, if you're using Xtol 1+2, you need 200 ml of stock, which means 600 ml of working solution to meet the recommended minimum). If you're running more common dilutions (Rodinal 1+25, HC-110 B, D, or E, or D-76/Xtol 1+1) you should be okay with no changes.

jnamia · Apr 25, 2022

bags27 said:
Hi all,

Lurked for a long time. Recently decided to give Barry Thornton's 2-bath a try (just ordered the chemistry from Bostick & Sullivan), and read David Allen's entries on it, and pretty soon read every David Allen entry on everything and then pretty much everyone else's entries on everything for the past decade. I'm told I'll soon be released after I convince just one more psychiatrist.....

One of the many things I learned is that you can double up 120 film on a reel. Of course. Duh! But just wondering if it affects the chemistry. After all, the total exposed surface of 2 120 rolls is going to be more than the surface even of a roll of 135 film. Has anyone noticed a difference between using one or two strips/reel? I suppose it shouldn't affect a compensating developer much, but still it creates a pretty significant variable in a process for which optimally we eliminate variables.

Thanks so you all for so many incredible conversations (and debates) on this thread. It's a treasure trove for me.

HI bags27
After you process your film can you report back to this thread and let us know how it worked out? I've never used that specific developer or doubled up on my film on reels but I've done all sorts of things I was told not to do. I don't want to be one of those people that says DON'T when my concerns don't matter, and my lack of experience with your process makes my suggestions moot. I've never doubled up film, although for decades I've heard this is helpful, am leery of suggestions without proof the film didn't get screwed up. I figure it's a risk of scratching or damaging the film more than anything else, even though I've been spooling film for decades it's something I can see myself doing ..as I spooling klutz. and using 2x the amount of film through a developer that is usually considered the optimal chemical soup of active ingredients for 1 film, I can see why that would be a problem. I'd suggest using a larger tank and put 2x the developer in it ( then what's the point of double up on the single spool ? ). I've cooked a fair amount and know if I make bread with 6 cups of flour and only use the amount of salt or yeast for 3 cups of flour it might not work out, there's a lot of similarities between darkroom work and making bread. Maybe film is different, IDK. I hope you do your first batch with rolls that aren't important before you make it a regular event, and also process a single roll as a "control" and compare to see if potentially spent developer under-developed your film ( or if your doubled up film is full of micro abrasions).

good to read you are having fun
john

JerseyDoug · Apr 25, 2022

Understandably, literature from the film or developer manufacturer does not address developing two rolls of 120 film on a single 120 reel. And I can't remember seeing references to developing 220 film either. But they certainly do address developing a 36-exposure roll of 35mm film in a single-roll 35mm tank. And since a single-roll 120 tank has roughly twice the volume of a single-roll 35mm tank the developer volume and dilution specified for a single roll of 35mm film will be correct for two rolls of 120 film on a single reel.

Donald Qualls · Apr 25, 2022

JerseyDoug said:
the developer volume and dilution specified for a single roll of 35mm film will be correct for two rolls of 120 film on a single reel.

This.

That said, some of the common practices don't put enough active developer into a single 35mm tank, either. Manufacturer recommendations are another thing, but don't cross up the two.

JerseyDoug · Apr 25, 2022

Donald Qualls said:
This.

That said, some of the common practices don't put enough active developer into a single 35mm tank, either. Manufacturer recommendations are another thing, but don't cross up the two.

Some manufacturers address that too. From the Adox Rodinal data sheet:

"When using high dilutions and small developing tanks, please make sure to apply on each film 35mm or 120 at least 5 ml of concentrated developer."

faberryman · Apr 25, 2022

Why do you want to double up rolls of film on one reel?

Sirius Glass · Apr 25, 2022

Use enough chemistry to cover the film and pour the chemical back into a larger volume of the same chemical.

Donald Qualls · Apr 25, 2022

JerseyDoug said:
Some manufacturers address that too. From the Adox Rodinal data sheet:

"When using high dilutions and small developing tanks, please make sure to apply on each film 35mm or 120 at least 5 ml of concentrated developer."

Yep, Kodak does the same, at least for Xtol.

faberryman said:
Why do you want to double up rolls of film on one reel?

When I do it, it's in order to get more film done in fewer batches. I can fit four rolls of 120 in my "3-reel" size Paterson Super System 4 tank if I double up. If I've got three or more rolls that take the same process (including C-41), I can get them done in half as many tank runs.

Sirius Glass · Apr 25, 2022

faberryman said:
Why do you want to double up rolls of film on one reel?

Developing more film at one time.

faberryman · Apr 25, 2022

When you put two 120 rolls on one reel in a one reel tank, unless the solution contains enough developer for two rolls, you need to add more developer, which changes developer dilution. Does that not also change developing time?

MattKing · Apr 25, 2022

faberryman said:
When you put two 120 rolls on one reel in a one reel tank, unless the solution contains enough developer for two rolls, you need to add more developer, which changes developer dilution. Does that not also change developing time?

This only comes into play with relatively low volumes of working strength developer and very dilute solutions.
And with 120 film, those low volumes - significantly less than 500 ml - are only possible if one is using rotary agitation. If inversion agitation is used, most reel sizes are going to need at least 500 ml of working strength developer to physically cover the reels.
There aren't a lot of developer dilutions that are so dilute that 500 ml of working solution isn't enough to develop two rolls.
500 ml of HC-110 in unofficial dilution H (1 +63) would be one problematic developer dilution. XTol 1+ 3 would be another. But D-76 1 +1 and XTol in any more concentrated dilution would be fine.

MattKing · Apr 25, 2022

faberryman said:
If that is the case, it sounds like most people are using an overly concentrated developer, and pouring money down the drain. Or they are saving time.

Unless you are running a high volume commercial developing line, it doesn't make practical sense to optimize your process based on the criteria of minimizing the amount you are spending on developer. Other variables like quality of results, ease of handling, ease of use and repeatability of results are much more important for most of us. That being said, if your setup makes it practical to use higher dilutions and obtain equally good results with all normal versions of your normal procedure, then it makes sense to use those higher dilutions, and save some money.

faberryman said:
I still think some time adjustment might be necessary if you are developing two rolls in the same solution as you do for one, but have no interest in testing to find out.

As I posted above, once you pass a certain threshold of active developer per roll being present, it seems that it is the concentration of developer as a whole that determines the quality of the result, irrespective of the total volume being used.

mshchem · Apr 25, 2022

Paterson states the volume required on the bottom of the tank. It's the same for 120 and 220. Paterson assumed people would use a normal developer from Kodak, Ilford, Agfa etc.
D-76 or HC-110 dilution B replenished was my standard developer before I became enamored/encumbered with Jobo and one shot.

gone · Apr 26, 2022

MattKing said:
It is actually a good thing to wonder about.

I agree, and I'm still not sure about it. When I read the op's post, I thought it was about needing more developer. If the volume isn't increased, then they're asking the same amount of developer solution to develop 2 rolls, not 1. Seems like it would need additional time or additional developer, but I don't know that.

So, can it do that w/o losing any efficiency? This is something I wouldn't trust to thinking about it, I'd test it empirically by actually doing it, and seeing w/ my own eyes what happens. Might be fine, might need more developer to do twice the work. No way to 100% know until it's tried.

Donald Qualls · Apr 26, 2022

momus said:
same amount of developer solution to develop 2 rolls, not 1. Seems like it would need additional time or additional developer, but I don't know that.

That depends what solution you're using. Xtol or D-76 stock, D-23 stock, HC-110 B, you don't need to change anything (except the amount of replenisher if you're replenishing). Rodinal 1:50, you'll probably find some level of compensation beyond what you're used to.

MattKing · Apr 26, 2022

momus said:
Seems like it would need additional time or additional developer, but I don't know that.

It doesn't need more developer if there is already more than enough in the tank to do the job.
If the amount of developing capacity in the working solution in the tank is so small that it gets used up, you need more.
As an example, 500 ml of 1 + 1 XTol has enough capacity to develop 2.5 rolls of film - you are fine with 2 rolls in there.
But 500 ml of HC-110 dil H (1 + 63) only has enough capacity to develop 1.5 rolls of film - you are risking the effects of developer exhaustion with 2 rolls in there.

abruzzi · Apr 26, 2022

Rodinal 50:1 would probably have issues as well. I’ve read 7ml per roll, is the minimum, and 50:1 is 10ml, so may have difficulty with two rolls.

NB23 · Apr 26, 2022

Absolutely not.

8x10 square inch film requires 250ml developer.

One 120 roll requires 500ml to fully immerse, but it uses only 250ml capacity, therefore using half the capacity.

Therefore, you can either re-use the developer for another 120 roll, or develop TWO 120 rolls mounted back to back in the 500ml and discard.

Remember this, turn it how you will, it all comes down to the same:

36 exp = 120 roll= 8x10 = FOUR 4x5 sheets = 250ml developer.

1L develops:
-FOUR 36 exp rolls.
-SIX 24exp rolls
-FOUR 120 rolls.
-TWO 220 rolls.
-SIXTEEN 4x5 sheets.
-FOUR 8x10 sheets.

Sirius Glass · Apr 26, 2022

faberryman said:
When you put two 120 rolls on one reel in a one reel tank, unless the solution contains enough developer for two rolls, you need to add more developer, which changes developer dilution. Does that not also change developing time?

No, just use enough developer. Cheaping out to stretch developer and other chemicals leads to costly unrecoverable mistakes.

Does doubling 120 film on a reel mean more developer, too?

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Does doubling 120 film on a reel mean more developer, too?

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