I use Ilford for 35mm film development, 200 ml for developer, stop and fixer (with Paterson tank). I cannot find any information about quantity and mixing of 120 film.

How much would I need for it?

  • 1
    We must have different Patterson tanks. Mine says to use 290mL per 35mm...
    – OnBreak.
    Jan 26, 2019 at 19:55

3 Answers 3


My Patterson tanks are dual 35mm or single 120 rolls. On the bottom of the tank, the minimum amount for 120 is listed as 500mL. So, you need enough dev/stop/fix to make at least 500mL.

You can add as much as 580mL (which covers 2 35mm rolls), though the extra isnt necessary.

I haven’t tried running other films through my 4x5 Patterson, so can’t say if using that tank changes things.


It’s easy to discover the volume of fluid needed. Place the 120 reel in the tank and fill the tank with water. Add water until the reel is completely submerged, then add a touch more so that the water level is about 1/8 of an inch (3mm ) above the reel. Pour the water into a measuring bowl. Now you know the minimum amount needed for a 120 film reel.


I have big batches (about 2.5 litres) of stop bath and fixer mixed up because one of my tanks needs 2.4 litres to be filled.

While I measure developer accurately, with stop bath and fixer, I simply fill up the tank enough so that the roll is filly immersed in chemistry. If in doubt, just fill almost to the top. As long as there is a small air space, inversion agitation will help you keep the chemistry moving during your agitation process. There is no need to be carefully accurate as long as you have enough to fully immerse the film.

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