Mixing film sizes

[Pieter12]

I know this might seem like a pretty silly question, but is there any issue with mixing 120 and 135 reels in a Jobo or Patterson tank? I have a backlog of about a dozen rolls of mixed sizes to develop and might want to combine a couple of different size reels in the same tank. Same emulsion and ISO of course.

 

[ann]

Check the developing times. If they are the+same no problem

However it/is not uncommon for 120 to have a different time than 35mm

 

[MattKing]

I do it frequently.
Be sure to double check that you use the right amount of chemicals.

 

[Ian Grant]

I regularly process 5x4 and the odd 120 or 35mm in the same tank, have done for 40+ years,

Ian

 

[RalphLambrecht]

I know this might seem like a pretty silly question, but is there any issue with mixing 120 and 135 reels in a Jobo or Patterson tank? I have a backlog of about a dozen rolls of mixed sizes to develop and might want to combine a couple of different size reels in the same tank. Same emulsion and ISO of course.

no problem whatsoever. I would even go as far as averaging out recommended development times but definitely use two-bath fixing or double fix.

 

[cmacd123]

the difference in developing times is a legacy on when 35mm was typically printed with a condenser enlarger and 120 was printed by diffusion enlarger. this made for different preferred contrast for the two sizes. I understand that not many films use a different formula for the actual coating.

 

[voceumana]

You could always use a 2-bath developer like divided d76 or Barry Thornton's 2-bath. Contrast might be a little reduced (which can be a good thing or not) but nothing that printing can't resolve.

 

[MattKing]

I understand that not many films use a different formula for the actual coating.

There might be a problem here with nomenclature.
The emulsions do need to be adjusted between the formats, due to the differences in substrate and anti-halation.
And Charles' observation about enlargers is interesting.
I'm wondering though if the differences may be more general - that the target contrast for some of the 35mm emulsions may have traditionally been different than the the target contrast for some of the 120 emulsions.
Of course, one wrinkle that can be found in some of the Kodak emulsions is the fact that there were different, similarly named films in the two formats. For example, in my 1970 edition Kodak Darkroom dataguide there is Plus-X Pan Professional in roll film sizes and Plus-X in 135 and they required different development. In contrast, Tri-X Pan and Panatomic-X were available in both formats, and the development recommendations are the same.