Quote Originally Posted by Photo Engineer View Post
... but I know this, that single wash baths are not efficient.
Here is the reason:

Wash 1 can only remove 1/2 of the chemicals from the coating.
This is a law of science shown by Mason.
Wash 2 can only remove 1/2 of the remainder using the same math.
Wash 3 can only remove 1/2 of #2.

And etc. You approach zero but never get there because the wash
water you use never has zero chemistry in it. It always equillibrates
with what was in the film from the past condition. PE
That is not correct. Common sense itself dictates other wise.
The volumes of fresh water each wash vs the remaining volumes
of contaminants is very lopsided in favor of the fresh water and
the more lopsided with each succeeding wash.

A somewhat typical example: A tank is drained of fixer. Within
remains only that fixer which adheres internally to tank and
film; perhaps 20ml +/- remains.

Add 500ml of fresh water then let soak with some agitation.
As a matter of practice the first soak need not be any more
than a rinse; 2 minutes will do. The great bulk of the
remaining fixer is removed.

With the second 500ml dose of fresh water we are primarily
cleaning the emulsion itself. Perhaps a 2ml equivalent of full
strength fixer remains. As a matter of practice the second
soak should be protracted and with some little agitation.
Fresh water diffuses inward, fixer outward. Good thing
emulsions are of gelatin and very thin.

The third soak with some little agitation should be yet
more protracted. Dan