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B&W reversal with 2 films in the tank

SalveSlog

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Sep 29, 2013
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270
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Southern Norway
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I'd like to reversal process 2 films in one tank. I use the Ilford recipe. The recipe don't mention what kind of film (135, 120 or sheet) so I guess it's for 1 roll of 135. I have a suspicion that if I put 2 films in the tank, the added sodium thiosulfate will not be enough. So before I try, some of you may already know the answer:

Is the amount of sodium thiosulfate in reversal B&W consumed by the silver halide, so I will have to increase the amount when processing 2 (135) films in the usual (300ml) amount of developer?
 

ruilourosa

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Apr 13, 2003
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Portugal
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It´s a per liter amount! if you develop 2 you have to double the amount of the developer. Usually you have a 8 to 12 gr per liter of thiosulfate. So you have to do a racio for the amout of developer you use.

Thinking in consumption of chemistry by the silver halides is not a good thinking, the other way around is closer, and it would be valid for the other chemical compound of the developer. Don´t think about it, just use the formula correctly with the correct amounts.

by the way, keep the thiosulfate amounts to a minimum possible, it eats away your max density.

Cheers

Rui Lourosa