D-19 pour back

Hello,

When I use D-19, I dilute it various ways and use it one shot, and sometimes as a second developer bath, but never straight. However, I am mixing up a batch for the "experimental" photography class, and I want to use the "pour back method", due to the fact that there will be 24 students processing film for high contrast/halftone effects. Each gallon has a capacity of 60 rolls when using a hand inversion tank. Does anyone know after what percentages of this capacity you need to add time, and how much? Can I assume that it is the same as with D-76, where you need to add 10% more time after every 4 rolls of 135/120?

D-19R, replenisher calls for 25ml per 80sq.in. But it is a more concentrated in the developing agents then D-19.

Hi,

Thanks. We are using non-replenished developer, poured back and reused for logistical reasons. Doing it this way, after a certain number of rolls, you are supposed to add time (usually 10%).

If I don't hear any different, I am going to assume that the procedure is similar as it is for D-76, which is good for 40, if I remember properly. With that developer, I remember adding 10% time for every four rolls, which would be 10% time for every 10% of developer capacity that was used up. With D-19's 60 roll capacity, that would be an additional 10% after every 6 rolls.