Originally Posted by brbo
"Completely exposed" meaning completely black?
Completely exposed (everything black) can only be from light before development (and a fair bit for rolled film the get the whole roll). Completely exposed (but with clear edges) can only be from overexposure in camera. Completely clear is the film having never been exposed to light, or you but in the BLIX first.
I think the OP means clear.
Edit: one other thought, if the BLIX is exhausted totally then the unexposed silver won't be removed, making it look totally exposed to light. The BLIX is also the first to go in the powder kits, it's a pretty unstable compound, whereas a partially exhausted developer will just look underdeveloped and can be compensated for by increasing the time.