How much D-76 1:1 do I need to develop 2 rolls in one reel? How about 2 rolls in 2 reels (4 rolls)?

Lachlan Young said:

The more I look into this, the more perplexing it becomes...

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I only discovered the "2 US ounces per 4x5 sheet" recommendation while looking to explain my really long developing times to reach ASA criteria (0.62 Contrast Index)...

And I hate to say anything negative about Paterson tanks because I like them and I know my criticism is unfair. I am sure my experience is not typical.

To its credit, though I rapped very hard, the tank never chipped or cracked.

As a point of hopefully useful information, my developing time is 13 minutes 30 seconds for 400 speed Kodak films - so you see I ignore all the published times and develop longer than the times you will find elsewhere. I think a lot of the reason I have to develop this long... has to do with the fact that I often use the amount of D-76 1:1 that fills the tank... Which almost always is less than the recommended amount.

Kodak has a data sheet (j78) which specifies that the useful capacity of D76 mixed 1:1 is two rolls (135-36 or 120) of film per litre of working strength developer. You can find this information in the table at the top of page 7: http://imaging.kodakalaris.com/sites/prod/files/files/resources/j78.pdf

That recommendation is no doubt conservative, but when it comes to developer capacity, I am conservative as well.

The Ilford datasheet for ID-11 (and other powder developers) is more confusing, because it seems to direct that in order to have sufficient capacity to develop several films, you need to develop them individually in stock developer, pour the used developer back into the working solution and then extend the developing time each time. Proceeding that way with stock ID-11, Ilford indicates that a litre of stock ID-11 is sufficient to develop 10 rolls.

As for loading two rolls of 120 on a single Paterson reel:
1) I do it regularly in Paterson tanks with the AP/Arista Premium/Samigon reels which are the same size as the Paterson reels. I get nice even development (with HC-110 dil E replenished) and I have no problem with overlap, provided I make sure of a few things (see what follows);
2) Those and the Paterson reels are designed to take 220 film, which means they have the capacity to load two 120 films;
3) Early on, I tried to do this and use rotary agitation throughout. I had problems;
4) A pre-wet step seems necessary to prevent film overlap;
5) Inversion agitation in the developer seems necessary to prevent film overlap;
6) When I have used a pre-wet step and then followed that with inversion agitation in the developer, I can use rotary agitation for the stop bath, both fixer and HCA steps without encountering film overlap.

There are two criteria that you need to meet in order to develop the film correctly. First, you need to make sure the film is covered by the developer. Second, you need to have the minimum amount of developer per roll.

You are using D76 1:1. Kodak recommends 500cc, in other words 250cc of stock solution, per roll. Some people say this recommendation is conservative because only 150cc of stock solution (300cc at 1:1) is "needed" to develop a roll of 135. But you run a risk....If there isn't enough developer, I would guess the highlights would not develop to their full potential. Since I haven't conducted any experiment, I simply choose to build in a bigger margin of safety.

If you use a different developer, such as Rodinal and choose to use it at a dilution of 1+25, you would only need 260cc per roll.

But to cover one roll in a Patterson tank, you will need 500cc. Other tanks will have a different physical minimum.

So you can develop 2 rolls of 120 on one reel in a Patterson tank using an alternate developer.

I have tried this method before and failed. I have also had success in the past. But the sense of disappointment and regret is much greater than any savings, so I have decided not to do this on a Patterson tank. And yes, I have tried it with the tape.

The Jobo reel has a clip which prevents movement, and I feel much more comfortable putting two rolls of 120 on a single reel.

Bill Burk said:

As a point of hopefully useful information, my developing time is 13 minutes 30 seconds for 400 speed Kodak films - so you see I ignore all the published times and develop longer than the times you will find elsewhere. I think a lot of the reason I have to develop this long... has to do with the fact that I often use the amount of D-76 1:1 that fills the tank... Which almost always is less than the recommended amount.

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Have you measured what sort of contrast index this is giving? The Kodak datasheet suggests that you should be hitting 0.70 at that time...

MattKing said:

The Ilford datasheet for ID-11 (and other powder developers) is more confusing, because it seems to direct that in order to have sufficient capacity to develop several films, you need to develop them individually in stock developer, pour the used developer back into the working solution and then extend the developing time each time. Proceeding that way with stock ID-11, Ilford indicates that a litre of stock ID-11 is sufficient to develop 10 rolls.

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I'd guess that's where the 100ml/roll extrapolation came from.

Lachlan Young said:

Have you measured what sort of contrast index this is giving? The Kodak datasheet suggests that you should be hitting 0.70 at that time...

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Yes, I keep close tabs on my contrast index - it's one of my pet subjects here. At development time 13:30 I get 0.62 CI with TMY-2 and Tri-X, 4x5 in trays, 120 2-reel and 35mm 4-reel "small" steel tank - often when I miss my target, my contrast is lower than my time/CI chart predicted. (0.62 CI is a high aim for most people, 0.56 CI might be what Kodak considers "Normal").

Bill Burk said:

Yes, I keep close tabs on my contrast index - it's one of my pet subjects here. At development time 13:30 I get 0.62 CI with TMY-2 and Tri-X, 4x5 in trays, 120 2-reel and 35mm 4-reel "small" steel tank - often when I miss my target, my contrast is lower than my time/CI chart predicted. (0.62 CI is a high aim for most people, 0.56 CI might be what Kodak considers "Normal").

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Interesting - my own experience tends to say I'd be definitely closing in on the 0.7 range at those times, pretty much as per the published data. I note that Kodak states that 13:25 is a 2-stop push on TX with D76 1:1.

If it works, it works!

Before I forget, the Xtol tech pub states 100ml/80 sq in as the minimum stock solution - another possibility for the oft stated '100ml' claim.

Kodak says useful capacity of D-76 at 1:1 is eight rolls of 135-36 per gallon, or 2 per liter.

8 rolls per gallon = two rolls per 32 oz, or 2 rolls per 926ml.

Lachlan Young said:

Interesting - my own experience tends to say I'd be definitely closing in on the 0.7 range at those times, pretty much as per the published data. I note that Kodak states that 13:25 is a 2-stop push on TX with D76 1:1.

If it works, it works!

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Probably because Kodak considers 0.62 CI to be a push... for a long time I was calling 0.62 CI "Normal" until @Stephen Benskin pointed out to me the ASA parameters aren't "Normal".

We're only talking one or two minutes anyway. You get pretty much what the published data suggests, while I get a tad less (so I need to develop longer than you do). The good thing about it, after a while, we all become consistent. And once you become consistent, all kinds of great things start to happen.

Two rolls of 120 film on a standard 120/220 reel really isn't all that difficult from my limited experience, and reading comments from others who have been doing it longer than myself I can't really say I would consider it all that hazardous.

My personal preference for loading the reel (standard Paterson ones, new and well cleaned) is to take the the film+backing paper off the reel and allow to loosely coil. Then feed the first roll of film onto the reel at the same time I separate it from the backing paper. As I finish off the first roll I will leave an inch or so off the reel and remove the tape for the backing paper. After getting the backing paper well clear of things I'll prep the second roll, then carefully adjust the first roll, align the second roll's film so that the tail of the first overlaps on top of the lead of the second roll, and use the tape to tack them together. First few twists are very gentle to make sure it is taking up properly, but then it has consistently been easily sailing from there.

Develop them as if they were a roll of 220, and then be careful when you take them off the reels.


Some braver souls than myself apparently will load 4 rolls of 120 onto a single reel by going with the film back to back and washing backing off in a secondary cleaning process. While I like the time saving factor of being able to prep and load 2/4 rolls at once, I think the quad load is getting a bit 'nutty'.

cliveh said:

Do not roll two films onto one reel.

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Some people can do that I have trouble with one.

Xmas said:

Some people can do that I have trouble with one.

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Sometimes, so do I.

I think the idea of two rolls in one reel is a good idea, rather than i use two reels so it will take more chemicals then.

I hope one day if i can buy a processor automated so i can develop more film, i enjoy developing one film at once, and mostly i use different films so that i process film individually or separately.

I think the only way i may develop either 2 rolls in one reel is to buy more same films to shoot more or test more without much risk of important frames, but if i will go with the other option by using two reels then i want to find that developer which are in big volumes and use less dilutions so i can develop a lot in big tanks and still have the developer not finished, the only issue will be with fixer and or/stop bath then if there are not big volume quantity of then too.