Thanks for that explanation, Ron. I didn't read your post carefully enough to realize you were talking about washing. I thought it was about development agitation.

The method I use to wash film is with an upright dedicated film washer, where the reels are stacked on top of each other, just like in a developing tank. Extra air is introduced to the wash water, which causes a type of turbulent water flow. No air bubbles accumulate on the film surface in this washer, but I imagine that with plain running water it might.

Quote Originally Posted by Photo Engineer View Post

Look at the film as it washes. You will see tiny bubbles on the film caused from air entrained in the wash water. This can cause uneven washing with resulting dots of brown from retained hypo. We called it "measles". So, some sort of agitation should be used even in the wash. I just remove the reel from the tank and tap it a few times, then return it to the wash tank. I do this every time I see the bubbles accumulate.

This is not well known.