How to develop 10 rolls of 120 film in C-41 chemicals at once?

moodlover · Aug 4, 2017

Hi all,

I am currently using the Paterson tank that holds 2x 120 reels in it. I load 2 rolls into each reel (by method of taping the end of one to another to effectively create one long roll, then reel it in). This method lets me develop 4 rolls successfully at a time with no issues.

But I have 48 rolls to develop. And 4 rolls at a time will take me days to get it all done which is not efficient.

I am now looking at the Paterson Multi-8 tank which holds 5x 120 reels in it, so if I put 2 rolls into each reel, I am thinking I can develop 10 rolls of 120 film at a time. The issue is this tank is super long and I have no idea how to keep it in a warm bath during developing (maybe using a huge bucket?). Honestly, im not sure how crucial it is to keep the tank in 39C water during developing?

Anyways, the other issue is how the heck do I fill up the chemicals fast enough? I believe the tank requires something like 2.5L of chemicals. My first idea is to cook up two batches of 1L chemicals and hope the total 2L covers the entire film/reels and the missing 0.5L won't affect it. Then I'll mix up these two separately cooked soups (is that a safe idea?) into one batch and store in a 2L measuring pitcher until I'm ready to use.

Thoughts? Advice please!

moodlover · Aug 4, 2017

My last question: with a big 2L pot of developer, how many rolls of 120 could I develop IF I develop non stop within one day (I never keep chemicals longer than a day).

With the regular 1L kit, people say they can push from 12-24 easily with no real difference, and I've gone up to 12 successfully but never risked more.

With a 2L batch, I am assuming I can go 24-48 unless I misunderstand how the chemicals work.

trendland · Aug 4, 2017

There is a method to have a test run ( only with water ) to messure the temperature lost within the time of development.
You just have to add some 0,--- degree to have the arithmetic mean.
But are you sure to develop 10 films at once ?
If anything could go wrong...... you possible lost 10 films.
Same films same E.I with all films ?

with regards

MattKing · Aug 4, 2017

I would suggest the tanks that take three 120 reels instead.
That would mean eight runs instead of five, but otherwise would be easier to work with.
And yes, you do need to maintain the temperature.

moodlover · Aug 4, 2017

trendland said:
But are you sure to develop 10 films at once ?
If anything could go wrong...... you possible lost 10 films.
Same films same E.I with all films ?

Hmm, well C-41 is standardized so either Portra 160 or 400 will both work in the same development times. What exactly can go wrong? Ive developed a lot of film before and usually what goes wrong is temperature or spills, but nothing drastic.

moodlover · Aug 4, 2017

MattKing said:
I would suggest the tanks that take three 120 reels instead.
That would mean eight runs instead of five, but otherwise would be easier to work with.
And yes, you do need to maintain the temperature.

Oy, good advice. Do want to stay safe but I'm thinking the one that takes 3x 120 reels would still require me to cook up 2L worth of chemicals since 1L is not going to be enough.

Really want to figure out how to bulk develop film in my house and not have to pay a lab here in NYC. $5/roll for processing is cheap until you've got 50 rolls to develop.

trendland · Aug 4, 2017

moodlover said:
Hmm, well C-41 is standardized so either Portra 160 or 400 will both work in the same development times. What exactly can go wrong? Ive developed a lot of film before and usually what goes wrong is temperature or spills, but nothing drastic.

I can´t say what may going wrong - I have most total different films with different E.I. a.s.o. I will not have 10 films at once.
But if you are well experienced it might be allwright....
with regards

Jim Noel · Aug 4, 2017

To maintain temperature use the "run-by method". If you normally lose 5 degrees during development, start 2.5 degrees above desired temp. It will end 2.5 degrees below desired, but average the desired temperature.

moodlover · Aug 4, 2017

Jim Noel said:
To maintain temperature use the "run-by method". If you normally lose 5 degrees during development, start 2.5 degrees above desired temp. It will end 2.5 degrees below desired, but average the desired temperature.

Thats a good tip, I guess I have to first figure out how much temperature my developer is losing in 3.5 minutes. Not sure if using water alone would work the same? I would assume in winter it loses much more heat than in the summer.

moodlover · Aug 4, 2017

Does anyone know if it's safe to mix up 2x 1L batches at the same time together in one pot?

For example, the usual technique is to get a 800mL of water into a pot then pour the developer powder in and mix it. BUT, could I effectively double everything and not cause any explosions in my bathroom? Say, 1600mL of water, pour in two packets of developer powder (slowly, once the first is mixed in), then fill up the remaining space with distilled water until I make 2L developer?

Basically, double the water + double the developer. Should be fine, no? Or is this dangerous?

MattKing · Aug 4, 2017

moodlover said:
Does anyone know if it's safe to mix up 2x 1L batches at the same time together in one pot?

For example, the usual technique is to get a 800mL of water into a pot then pour the developer powder in and mix it. BUT, could I effectively double everything and not cause any explosions in my bathroom? Say, 1600mL of water, pour in two packets of developer powder (slowly, once the first is mixed in), then fill up the remaining space with distilled water until I make 2L developer?

There certainly won't be any explosions.
The challenge is always assuring complete mixing and full uniformity.
Two litres is a pretty small quantity, so it wouldn't normally concern me. But if you are worried, mix each litre separately, and then add one to the other in your big pot.

foc · Aug 4, 2017

As MattKing said above, there will be no explosions. I have never used a C41 home kit but I have processed C41 professionally for the last 38 years.

I can't see any reason not to double up as you suggested, the instruction seem simple enough. It is the dev temp that is the most important. Again you have been given very good advice above.

The comments on the different film EI...... well I don't understand that. C41 is a standard colour negative film process regardless of the film ISO or ASA. (unless you want to push a film and that's a different matter.)

I look forward to hearing how you get on.

mshchem · Aug 4, 2017

Check out this former posting You will need to replenish, I would do it in the dark in tanks in a water bath. Take your time enjoy the scenery . Buy the Flexicolor RA materials and you will be able to process 10 rolls in 10 minutes or less. I would use a wash at the end rater than 3 stabilizer bathes . Use the minilab materials either buy the cartridges or the bulk, The Bleach is eternal, Developer and fixer is dirt cheap from unique Photo in NJ

(there was a url link here which no longer exists)

faberryman · Aug 4, 2017

It seems like you are asking the question: "What is the quickest and cheapest way I can possibly screw up developing 10 rolls at a time?" I had to develop 30 rolls of black and white a couple of months ago. I did it four rolls at a time. Sure it took a while, but there was no drama and they all came out perfectly. Patience is a virtue.

moodlover · Aug 5, 2017

faberryman said:
It seems like you are asking the question: "What is the quickest and cheapest way I can possibly screw up developing 10 rolls at a time?" I had to develop 30 rolls of black and white a couple of months ago. I did it four rolls at a time. Sure it took a while, but there was no drama and they all came out perfectly. Patience is a virtue.

Where exactly does your pessimism come from? Genuinely curious. A tank holding more reels requires more chemistry, but once you have that, you would fill it up the same way as using less reels and develop/agitate the same time and method. What can possibly screw up? Please, enlighten me.

I am patient, but I do not have 4 days free to do this.

MattKing · Aug 5, 2017

It looks to me like faberryman is a subscriber to Murphy's Law, while moodlover is not .
One of the reasons that people recommend splitting up a large block of film over several development runs isn't to reduce the chance of something going wrong, but rather to reduce the number of films that will end up being damaged if something does go wrong, as unlikely as that may be.

bvy · Aug 5, 2017

moodlover said:
Anyways, the other issue is how the heck do I fill up the chemicals fast enough?

You don't! I can't believe no one has addressed pouring times. At just over three minutes, C-41 development takes place fast! You can check to see how much time it will take to get the top reel completely submerged in whatever size tank you end up using, but anything more than about eight seconds is too long. Forget the funnel. For large loads, better to drop and lift the reels into and out of the developer and into your next bath. This can be cumbersome with Paterson tanks since the center column isn't really designed to work like a lifting rod. If you go that route, best to have your next bath ready to go in a separate vessel that can receive the reels.

Here is what uneven development from slow pouring looks like. And this was a two reel tank with just two 120 reels (this was on top, of course). Not pretty. And, yes, I used a pre-wash -- two of them in tempered water.

ETA: My example was with a stainless steel tank and reels. I know the Paterson tank is designed to fill up evenly from bottom to top, but I still wouldn't trust it to keep developer away from dry film before the fill line reaches it. The other issue with excessively long fill times is the top reels will get less development time than the bottom reels -- again, more of an issue with C-41 since the development time is so short.

faberryman · Aug 5, 2017

moodlover said:
What can possibly screw up? Please, enlighten me.

One question might be how long does it take to fill and empty an eight reel tank, and the follow up would be will the bottom reel receive the same development as the top reel?

moodlover · Aug 5, 2017

faberryman said:
One question might be how long does it take to fill and empty an eight reel tank, and the follow up would be will the bottom reel receive the same development as the top reel?

That is a good question, one I asked before regarding the 2x 120 reel tanks. Someone told me if it takes 8 seconds to fill up, start pouring out at 3:22 so that it will take 8 seconds to dump the chemicals out. A "first in, last out" technique. It worked well for me. BUT, for a 5 reel tank I am wondering how the heck others do it in time. There must be a solution or two if this tank exists and is for sale.

moodlover · Aug 5, 2017

bvy said:
You don't! I can't believe no one has addressed pouring times. At just over three minutes, C-41 development takes place fast! You can check to see how much time it will take to get the top reel completely submerged in whatever size tank you end up using, but anything more than about eight seconds is too long. Forget the funnel. For large loads, better to drop and lift the reels into and out of the developer and into your next bath. This can be cumbersome with Paterson tanks since the center column isn't really designed to work like a lifting rod. If you go that route, best to have your next bath ready to go in a separate vessel that can receive the reels.

Here is what uneven development from slow pouring looks like. And this was a two reel tank with just two 120 reels (this was on top, of course). Not pretty. And, yes, I used a pre-wash -- two of them in tempered water.
View attachment 183886

ETA: My example was with a stainless steel tank and reels. I know the Paterson tank is designed to fill up evenly from bottom to top, but I still wouldn't trust it to keep developer away from dry film before the fill line reaches it. The other issue with excessively long fill times is the top reels will get less development time than the bottom reels -- again, more of an issue with C-41 since the development time is so short.

Very weird, I never had this problem with my 2 120 reel tanks. I pour directly from a large 1L measuring beaker into the tank and it takes 5 seconds or so. Then at 3:25 I start pouring out so the roll at the top that received 5 seconds less development at the beginning gets the last 5 seconds to make up for it.

Your idea of going dip-and-dunk is great but I have a huge window in my bathroom, so turning it into a darkroom is unlikely.

darkroommike · Aug 6, 2017

moodlover said:
Where exactly does your pessimism come from? Genuinely curious. A tank holding more reels requires more chemistry, but once you have that, you would fill it up the same way as using less reels and develop/agitate the same time and method. What can possibly screw up? Please, enlighten me.

I am patient, but I do not have 4 days free to do this.

Not counting drying time the entire C-41 process is only about 20 minutes.
A larger tank does require longer to fill and drain so no it will not be "just the same".
I use a Unicolor film Drum on a roller base and can do 3 rolls or 120 at one time, and no, even if I could I would not put two rolls per reel, you need enough developer capacity to process the rolls properly. (Unicolor once made a big drum, not sure how many rolls it held.)
I have also seen folks make tanks from PVC you then transfer the film from tank to tank in the dark. Richcolor used to make a "professional" system to do that thing with a water jacket, my friends sister used to process E-6 seven step, in open top PVC tanks and used a laundry utility sink for a water jacket. She also made an extended lift rod from PVC.

Cholentpot · Aug 6, 2017

I'm up to 32 rolls put through my standard kit. Would not recommend for good film though. Cut off is about 25 rolls. I'm developing expired portra 160 with the c-41 stand method so I'm not so worried about the results. Purple blacks never looked better.

moodlover · Aug 6, 2017

Cholentpot said:
I'm up to 32 rolls put through my standard kit. Would not recommend for good film though. Cut off is about 25 rolls. I'm developing expired portra 160 with the c-41 stand method so I'm not so worried about the results. Purple blacks never looked better.

Which chemicals do you use? Id love to get 20 out of my powder jobo/tetenal c-41 press kit but never tried more than 12 from one box. I develop everything in one day so I'm wondering if that would help me get to 20.

Cholentpot · Aug 6, 2017

moodlover said:
Which chemicals do you use? Id love to get 20 out of my powder jobo/tetenal c-41 press kit but never tried more than 12 from one box. I develop everything in one day so I'm wondering if that would help me get to 20.

The jobo/tetenal powdered press kit.

I buy one about once a year and go on a developing binge over a week. I have two, 2 reel tanks and one 2 reel stainless than I for the most part ignore. I tend to do 4 rolls at once. Takes about an hour start to finish. At about roll 16-20 I change over to stand development and switch over to developing my crappy film. About roll 24-25 is where the colors really start to shift. This is all 35mm mind you.

moodlover · Aug 6, 2017

Okay there's a update to this now:

I found a local lab that will let me rent their Jobo color processor. Apparently, it can process 10 rolls of 120 at a time (5 reels x 2 each). Has anyone used the Jobo processors before and can comment on its ease of use / consistency / quality of results?

How to develop 10 rolls of 120 film in C-41 chemicals at once?

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How to develop 10 rolls of 120 film in C-41 chemicals at once?

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