Film Bleach pH = brown stain?

[ZorkiKat]

If a ferric EDTA bleach goes alkaline, what happens to the film? Will it stain to the resulting negative? The 'chrome films I crossprocess come out like masked colour negatives when they should have 'clear' bases instead. I'm thinking that the home-brewed ferricEDTA bleach I'm using must be too alkaline. Don't have a pH meter to determine the pH of this bleach. Could this "mask" be iron stain? If this bleach is indeed slightly alkaline, will it cause this stain?

 

[Photo Engineer]

The C41 and E6 bleaches should have a pH value of about 6.5 or so at 20 deg C.

If they become alkaline, they can leave a brown stain.

If the bleach is not active enough (stale or too dilute) it can leave a brownish stain on slides due to retained silver.

Blixes sometimes leave a brownish stain on film if they are not strong enough.

It can also be retained silver halide due to a bad fix. Re bleach and fix with wash and stabilze will fix this but will not fix stain from iron. There is a fix, but it is rather difficult to do.

PE