Film Processing-How Much Empty Space for Tank Inversion?

Tom-Thomas · May 31, 2024

I use mostly Paterson tanks and reels. I always have one empty reel on top. E.g., for a 5-reel tank, I will put in 4 loaded reels at the bottom and one empty reel on the top. And I will fill the tank up with slightly more than enough chemical to fully immerse the bottom 4 reels.

My reasoning is that if I put in all loaded reels and enough liquid to cover all of them, there will only be a little empty space left and that's not enough for the liquid to have a complete "turn over" with the inversion agitation method. That's especially more of a concern for large tanks with numerous reels inside.

Do you do the same? What is your experience on this?

koraks · May 31, 2024

No, never did this and frankly I don't really share the concerns about the incomplete turnover. If you do two or three inversions, the contents of the tank will be pretty thoroughly mixed.

pentaxuser · May 31, 2024

Well the makers of the tanks will have made sure that when they specify an amount it covers the reels As the late Roger Hicks used to say, the makers have no incentive to advise you to use less volume than you need

That said I have always tended to use a few mls more to cater for the event that you may get some small leakage from the tank in the course of the inversions and development time

So in a Jobo tank for a 135 film Jobo say use 240ml but I usually put in 245 or even 250 ml. There is still plenty of room for developer movement

pentaxuser

Alan9940 · May 31, 2024

What koraks said...

I use 400mm in my Paterson single reel 35mm tank and 600mm in my single reel Paterson 120 tank. Over the years, I've used Kodak standard agitation, Ilford standard agitation, minimal / semi-stand agitation and stand agitation, and I've never seen any agitation caused issues with this level of chemistry in the tank.

JerseyDoug · May 31, 2024

I use 250ml in a single reel Kindermann SS 35mm tank and 500ml in a single reel Paterson 120 tank. Both are the minimum recommended by the manufacturer. I stick with those numbers because they let me use a nice round 5ml or 10ml of Rodinal for a 1:50 solution. I have been doing this for many years and have seen no issues I can attribute to too much or too little agitation.

mshchem · May 31, 2024

Nope. Don't over think this.

Saganich · May 31, 2024

mshchem said:
Nope. Don't over think this.

LOL, I always think that the velocity of movement during inversion will be higher the more space is left, which may be a factor for streaking, drag and other odd phenomena...especially when the bottom reel isn't covered when the tank is inverted. My thought is that all reels should be covered during inversion cycles and there should be a very small head space. Twisting may be more important than inversion anyway.

MattKing · May 31, 2024

The current version (for the last ~ 40 years) Super System IV Paterson tanks have a reservoir for air in the top that does the job. If you follow the tank directions that will give you enough air to ensure sufficient cavitation to create random enough agitation.
If possible, you want the chemicals to tumble randomly through the reels and film when you agitate the tank - you should be able to hear the gurgle.
For reasons of consistency, I prefer to always use the tank with the same amount of developer - the amount necessary (1 litre) to cover two 120 reels or three 35mm reels in the tanks I use most frequently. In my workflow using replenished developer, there is no cost penalty for doing that.

MattKing · May 31, 2024

My preference for the Kodak agitation recommendations - 10 seconds every minute - might reduce the importance of this issue, because the film and reels spend a longer continuous period in the developer between each agitation cycle.
However, the most important concern is whether you consistently do the same thing each time. Any slight variation between two different approaches will not matter if you are consistent.

jeffreyg · May 31, 2024

Matt +1. I use Kinderman tanks and tilt while pouring in. That lets the tank fill from bottom to top and lets air escape. I fill to the top of the underside of the tank cover so there is a small space for air above. Invert back and forth for the first 30 sec and then 3 every 30 sec and tap firmly on the counter. This has worked for me for 50+ years. No bubbles on the film. I shoot 120 film so if only 1 roll I use a one roll tank. If multiple rolls I use two roll tanks. I do the same regardless of which developer and also for fixer.

Augustus Caesar · May 31, 2024

Tom-Thomas said:
I use mostly Paterson tanks and reels. I always have one empty reel on top. E.g., for a 5-reel tank, I will put in 4 loaded reels at the bottom and one empty reel on the top. And I will fill the tank up with slightly more than enough chemical to fully immerse the bottom 4 reels.

My reasoning is that if I put in all loaded reels and enough liquid to cover all of them, there will only be a little empty space left and that's not enough for the liquid to have a complete "turn over" with the inversion agitation method. That's especially more of a concern for large tanks with numerous reels inside.

Do you do the same? What is your experience on this?

Fill the tank almost to the top. Leave just a little air space.

Sirius Glass · May 31, 2024

I never have needed to do that. On the other hand if I had a 5 reel tank and only 4 roll to develop, I would not hesitate to load that tank with one empty reel.

250swb · Jun 1, 2024

Tom-Thomas said:
I use mostly Paterson tanks and reels. I always have one empty reel on top. E.g., for a 5-reel tank, I will put in 4 loaded reels at the bottom and one empty reel on the top. And I will fill the tank up with slightly more than enough chemical to fully immerse the bottom 4 reels.

My reasoning is that if I put in all loaded reels and enough liquid to cover all of them, there will only be a little empty space left and that's not enough for the liquid to have a complete "turn over" with the inversion agitation method. That's especially more of a concern for large tanks with numerous reels inside.

Do you do the same? What is your experience on this?

The reason a bottle of orange juice has a small air gap is to allow the contents to mix. Of course you can stand with the fridge door open shaking the bottle vigorously and even make it froth because it doesn't matter, it will still come out as orange juice. But you can't do this with inversion agitation, you are relying on the amount of bubbles and eddies around the reels to mix the developer, and the fewer or smaller the bubbles the less mixing will occur. So if you leave almost no space for air when you invert the tank the developer at the bottom will now be at the top, but turn it back and it will still be the developer that was at the bottom. But it rarely if ever matters in a normal development time, the developer should not be exhausted anyway, it's only longer times and more diluted developers where attention should be paid to full re-mixing. The amount that it doesn't matter is highlighted by the fact that using the twiddle stick and no inversion is just as effective.

Disconnekt · Jun 1, 2024

I see it as as long you have enough liquid in the tank to fully cover the amount of film you're developing, you'll be fine.

Tom-Thomas · Jun 1, 2024

Looks like I am the odd man out. I've been using this method for decades and it's been working out great for me, so I'll keep doing it, if nothing but for the sake of consistency.

eli griggs · Jun 1, 2024

I feel that, as importaint as good agitation, that the "rapping' of the tank bottom is key to removing the initial and ongoing bubble formations.

I'm fairly aggressive when developing, both the rapping and agitation, with about four to five initial rap, agitation, and a lift and twisting motion in inverting the tank, setting it down with about a ½ to ⅓ rotation of the tank, with the rapping at the end of the cycle of five to however long the developer demands.

I pretty much fill the tank, of any size, and I've been happy with my developed negatives for most of fifty years, without regard for developer types, D-76 1:1, Pyro, Rodinal, Parrodinal, Caffinol, etc.

It's the resulting negative that is most important and how you'll print them, ie, as I learned darkroom work, I've always developed mine for graded #3 FB papers.

JerseyDoug · Jun 2, 2024

What are people doing that causes air bubbles?

I have been developing 35mm film in single reel SS tanks for 35mm and single reel Paterson tanks for 120 for years with no rapping of the tanks. I start agitation by inverting the tank firmly ten times with a quarter turn between inversions which takes about 30 seconds. I then give it between one and four (depending on the Rodinal dilution) gentle inversions at one minute intervals. I use the Ilford washing method and then add one drop of LFN for 35mm, or two drops for 120, to the last rinse water, followed by five more gentle inversions. No rapping at any time, and I have never seen anything resembling an air bubble.

snusmumriken · Jun 2, 2024

Just be careful rapping Paterson tanks. I'm not particularly vigorous about it, but I've twice chipped the flanges on the bottom of mine. Not a big deal, but it shows that the plastic is actually quite brittle.

Augustus Caesar · Jun 2, 2024

snusmumriken said:
Just be careful rapping Paterson tanks. I'm not particularly vigorous about it, but I've twice chipped the flanges on the bottom of mine. Not a big deal, but it shows that the plastic is actually quite brittle.

I use a couple of layers of towel on top of my work table.

eli griggs · Jun 3, 2024

snusmumriken said:
Just be careful rapping Paterson tanks. I'm not particularly vigorous about it, but I've twice chipped the flanges on the bottom of mine. Not a big deal, but it shows that the plastic is actually quite brittle.

I've also had that happen and if's it's in a cold environment it'll shatter easily.

This happened to me in my old family house's unheated kitchen, which at the time I was using as a darkroom, while living there, and photographing out of town during my days.

It was a room with tall ceilings and two low to high celling walls made of glass panels that were hinged on top to allow them to be open while it rained without water intrusion.

Before a dividing wall that made it separate from the rest of the room was built, there was a large, original kitchen separate from this one by what was a sunroom or conservatory, where you could also hang wet cloths.

The room was not heated, without running the oven and the window walls allowed most winter nights to drop to freezing temperatures.

I used the darkroom after dark, using black paper background rolls to keep out most light and it worked but did nothing to isolate from the cold.

Hot water baths and a large water heater at maximum settings, allowed me to develop and print as if it was a normal darkroom.

On this night, the temperature was below freezing when I got home, with film to develope and print and as I reached over to pick up a Patterson Tank and reels, with one hand, I caught my hand against the rack I was using for drying and storage my tanks, etc and i dropped that tank, with some reels already in it.

The plastic of the tank basically shattered on the floor, knocking the bottom right off.

The reels were just fine and I've never had a misadventure to damage one, though today I use steel tanks, reels, lids.

I also had pretty much forgotten this all, until this thread, having dropped or broken other plastics kept in the freezer or outside in the cold, over the last nearly forty five years.

Sunlight will also make some plastics fragile.

Film Processing-How Much Empty Space for Tank Inversion?

Tom-Thomas

koraks

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pentaxuser

Alan9940

JerseyDoug

mshchem

Saganich

MattKing

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MattKing

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jeffreyg

Augustus Caesar

Sirius Glass

250swb

Disconnekt

Tom-Thomas

eli griggs

JerseyDoug

snusmumriken

Augustus Caesar

eli griggs

Film Processing-How Much Empty Space for Tank Inversion?

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