I recently tried B&W reversal processing. I found the same problem I had with E6. The unexposed area (black) appear slightly uneven, and sometimes with slight flow marks. I supposed this was formed during one of the fast acting processes, as it takes time for the chemical to get evenly in contact with the film. Am I correct? And, which process would that be? Reverse, or bleach? The bleach I used for B&W is dichromate.