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# Thread: newbie question for B&W developer

1. ## newbie question for B&W developer

Right now I use Ilford Ilfosol 3, and ilford stop bath and rapid fixer. The instruction manual only tells the capacity in terms of 135mm films. However, I would like to know its capacity in 120 films. How to convert them?( 1 125mm = 1 120mm) ??? Many Thanks.

2. 36 frame 35mm equals 1 roll of 120. Basically the same square inches of film.

3. Usually depends on the size of the tank, but as a general guide using the figures on the bottom of my jobo tank.

135 10Oz / 290ml (round up to 300ml)
120 17.5Oz / 500ml

so to scale up multiply your 135 figures by 500/300, or 1.67 times more liquid needed for a 120 film

4. Are you asking about capacity as in how many rolls can be processed in a given quantity of chemistry? If so, Nick's answer is correct. If, however, you are asking about the volume of chemistry required by your developing tank, the easiest way to check is to assemble the tank and reel, put in enough water to cover the reel, but still leave some air above, and then measure the amount of water you used.

This is assuming you are using inversion agitation.

Hope this helps.

Matt

P.S. don't forget to dry the reel and tank afterwards

5. Nick and Aurum have answered two different questions. I suspect that jzhu was asking the question that Nick answered, but I'm not positive of that.

Most photochemicals have a certain capacity, in terms of square inches (or square centimeters, or whatever) of film or paper that can be processed per unit volume. By this measure, as Nick says, a 36-exposure roll of 35mm film is roughly equal to a roll of 120 film in surface area, and so either type of film will exhaust your fixer (or whatever) equally. This issue is most important when the photochemical is re-used, although it can also be important for single-use items when they're fairly dilute -- you might need a particular volume of developer to fully develop a roll of film, and if that volume is more than the minimum required to cover the film in the developing tank, you may need to use extra developer.

Aurum's point answers the issue I've just raised -- how much solution do you need to cover a roll? For this, 35mm and 120 are seldom equivalent, unless you process two rolls at once and, for 120 film, fit two rolls on one reel. Most tanks require 250-350ml of solution for a roll of 35mm, but about 500ml for a 120 roll. This determines the cost of single-use solutions, unless they're dilute enough that you need to add more than the tank's minimum. Most plastic tanks have their recommended minimum solution volumes stamped on them. For stainless steel tanks, measure to be sure what you need.

6. Thanks all. Nick answered my question.
Thanks for srs5694's full explanation.
I am using a metal tank that holds approx. 500ml liquid. I need about 400ml to cover my 120 film. I was wondering how much 120 films can I process using 400ml working strength developer. If 1 135mm(36 frame) = 1 120 film, I can calculate the number base on the number given in the user guide.

7. Originally Posted by MattKing
Are you asking about capacity as in how many rolls can be processed in a given quantity of chemistry? If so, Nick's answer is correct. If, however, you are asking about the volume of chemistry required by your developing tank, the easiest way to check is to assemble the tank and reel, put in enough water to cover the reel, but still leave some air above, and then measure the amount of water you used.

This is assuming you are using inversion agitation.

Hope this helps.

Matt

P.S. don't forget to dry the reel and tank afterwards

How do I dry them? I just rinse them with water, and hang dry. Is that good enough?

8. Originally Posted by jzhu
How do I dry them? I just rinse them with water, and hang dry. Is that good enough?
***********8

I was taught to use a vegetable bristle brush and Bon Ami cleaner, Zud, or Bar Keeper's Friend and scrub out the reel and tank. While doing that I run hot water through the tank lid. I rinse everything well, then I hang the reels on a peg board, and put the tanks upended with the lip just off the work surface to air dry.

9. what's Bon Ami cleaner?

10. Originally Posted by Aurum
Usually depends on the size of the tank, but as a general
guide using the figures on the bottom of my jobo tank.

135 10Oz / 290ml (round up to 300ml)
120 17.5Oz / 500ml

so to scale up multiply your 135 figures by 500/300,
or 1.67 times more liquid needed for a 120 film
So much for the solution volume needed. The amount of
developer needed for a 120 is the same as is needed for
one 135mm 36 exposure. Using the same amount for
the 120 will result in a more dilute solution. Allow
more time for development. Dan

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