Rolfe Tessem
Subscriber
The pre-soak thing has been discussed endlessly before.
The bottom line is that Jobo figured out that a five minute pre-soak allowed users to use the times already established for small tank inversion processing. That eliminated the need for running hundreds of tests with every possible film/developer combination to establish new rotary times. Kodak came out with Xtol after rotary processing had become established and therefore published times for Xtol in a rotary processor without a pre-wash. There is no other magic to it. Use one or don't, but adjust times accordingly.
The bottom line is that Jobo figured out that a five minute pre-soak allowed users to use the times already established for small tank inversion processing. That eliminated the need for running hundreds of tests with every possible film/developer combination to establish new rotary times. Kodak came out with Xtol after rotary processing had become established and therefore published times for Xtol in a rotary processor without a pre-wash. There is no other magic to it. Use one or don't, but adjust times accordingly.