Selecting a tank

[Bobonli]

Not your Jobo v Paterson thread. I'm actually trying to determine what size tank to order. I've been studying the Ilford Guide to developing B&W. The instructions pertain to the development of 1 roll of 35mm and call for a volume of chemicals of 300ml per stage.

Is 300ml fixed per roll of film or can I use the same volume in a 2 roll tank? Or for 2 rolls do I need to double the volume of chemical in the tank?

I'd like the capacity to do two rolls at at time, eventually.

I ask because the tanks seem to have "odd" volumes. A Jobo tank I looked at says it holds 250 for one roll or 485 for two:
http://www.bhphotovideo.com/c/product/25556-REG/Jobo_J1520.html

I couldn't find volume rating on the Paterson tanks. This leads me to believe that one 300 ml batch of chemicals can do two rolls in the 485ml tank but I also know I might have this completely wrong!!

Thanks for pointing me in the correct direction on this.
Bob

 

[semilog]

You should use enough developer to cover the reels that you have in the tank, or the amount specified by the manufacturer, which ever is larger. If you don't fill the tank, that's fine. I routinely develop two rolls in a 3-roll tank, using 600 ml of dev. Works fine.

 

[FPjohn]

250-300ml is a typical volume for a single reel (1 35mm film ) tank. A tank that takes two 35mm reels, ~ twice the volume of a single reel tank, will also typically take, alternatively, a single 120 film reel.

The actual volume needed to just cover the reel(s) can be measured directly with a graduated cylinder for any reel/tank combination.

A two reel tank is a good investment.

yours
FPJ

 

[Pirate]

I have a Arista tank that can take two reels of 135 or one reel of 120. This tank needs 350ml as a bare minimum for one reel of 135 and I use 700ml for 2 reels of 135 or one reel of 120.

I also have a Jobo (piece of junk!) that I use 490ml of solution in and that will cover 2 reels of 135 or 1 reel of 120.

As you can see from the numbers, the Jobo tank is much smaller/tighter than the Arista, and I hear this is typical of Jobo tanks so they do not need as much solution.

The Jobo tank is a model 1520.
The Arista does not have a model number on it, but it does give the following usage chart on the bottom:

1x135 /126 = 375cc
2x135/126 = 650cc
1x127 = 460cc
1x120/220 = 590cc

 

[RayPA]

I'd like the capacity to do two rolls at at time, eventually.

and probably sooner rather than later. I use my one-reel tank about 5-10% of the time (one-off jobs, etc). Processing is one of those activities that I enjoy, but if I'm going to do it, I prefer to get as much out of the effort as possible. If you're processing more than one roll, and you only have a single reel tank, you'll spend a lot of your time cleaning up. Depending on your work space, this can also increase the possibility of contamination. The single tank does come in very handy for those one-off jobs.





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[Fawley]

Its always nice to have a large tank in case you want to use highly dilute developers. Since you need a minimum quantity of developing agent, high dilution means more volume.

 

[Bobonli]

I have a Arista tank that can take two reels of 135 or one reel of 120. This tank needs 350ml as a bare minimum for one reel of 135 and I use 700ml for 2 reels of 135 or one reel of 120.

I also have a Jobo (piece of junk!) that I use 490ml of solution in and that will cover 2 reels of 135 or 1 reel of 120.

As you can see from the numbers, the Jobo tank is much smaller/tighter than the Arista, and I hear this is typical of Jobo tanks so they do not need as much solution.

The Jobo tank is a model 1520.
The Arista does not have a model number on it, but it does give the following usage chart on the bottom:

1x135 /126 = 375cc
2x135/126 = 650cc
1x127 = 460cc
1x120/220 = 590cc

I'm a little baffled by this, I'm sad to admit. If the directions on the developer call for 300ml for one roll yet the tank requires 650ml for two, does that mean I have to proportion out (scale-up the volume) of the chemicals to get to 650ml?

Isn't that a PITA when the recipe calls for an even 300 or 600 ml.

Thank you for helping me with this. I don't want to buy a tank that's too big and requires a bunch of extra chemicals.

 

[Pirate]

Yes it's a pain and I thought the same thing when I started doing this a couple months ago. I've been developing my own stuff since July now.

I usually just go with a set amount of chemical. For the Arista tank I'll use 400ml for 1x135 and 700ml for 1x120. I use Neofin Blau developer and it's made in 700ml batches, a one-shot developer.
For the Jobo tank, I use 490ml for everything.

 

[sevo]

I'm a little baffled by this, I'm sad to admit. If the directions on the developer call for 300ml for one roll yet the tank requires 650ml for two, does that mean I have to proportion out (scale-up the volume) of the chemicals to get to 650ml?

Isn't that a PITA when the recipe calls for an even 300 or 600 ml.

Well, if you are doing one-shot and do not want to dump considerable parts of your developer unused, you will have to use liquid stock developers. You cannot part out ready-mixed powder developers as they are not entirely homogeneous. Usually they are mixes of crystals and powders of quite different specific weight and crystal size so that some end up all at the top or bottom of the bag. And very critical components like stabilizers or activators may be present in so tiny amounts that they don't mix statistically - a single crystal or clump will always end up entirely in one of the parts while the others receive none of that substance.

For liquid developers it is trivial to calculate the ml/l from the mixing rules for a given quantity using the rule of three, if no x+y figures are given on the bottle or spec sheet. In doubt or when your maths skills are a bit rusty, use a pocket calculator..

Sevo

 

[semilog]

It's really not so bad. Every so often I mix up a big batch of XTOL stock, aliquot it into 10 or so 500 ml bottles, and open new bottles as needed. If I don't use an entire bottle of stock after I open it, that's ok, an open bottle keeps for at least 3 weeks (probably longer). It's really not a big deal.