Topic: What bleach dilution to use?

[Indofunk]

I want to experiment with the film acceleration scheme that Francois suggested to me for Ektachrome. He suggested a bleach step before the full color development cycle (instead of bleach and fix, because I won't let fixer touch any negs before the color developer), so I ordered some liquid concentrate from Freestyle. The bottle says to dilute 1+10 - 1+200. That's a huge range, what dilution should I use for C41 bleaching?

[Francois]

I guess it depends on how long you want the chemistry to last and how long you want your processing times to be.
You can always do a leader test to see how long it takes to fully bleach a developed leader...
Personally, I like to work fairly fast so I almost always prefer strong concentrations.

The good thing with bleach is that you really can't overdo-it.

[Indofunk]

How would I do a leader test? Does bleach actually clear a developed leader? No, that can't be true. Do I bleach the leader first and then develop it, and if it develops clear then it's completely bleached? I'm confusing myself here.

[Francois]

Just develop the leader until it's full black, rinse it and then dump it in the bleach and start the timer. When it turns clear, it's bleached.

If you do the opposite, you won't know for sure and you can mess-up a film completely.

[Indofunk]

That doesn't make sense to me. Follow my logic and tell me where I'm wrong...

A completely exposed leader should produce a black negative after the full C41 cycle, which in turn would produce a completely white positive (100% overexposed, etc). So the outcome of a leader is 100% black. So that means if I develop the leader (it will be black), and put it through bleach, and then fixer, it should remain black. How would either the bleach or fixer make it clear (white)?

[Francois]

If you want to do a film acceleration, you do a b&w developer and then a bleach that removes just the silver developed in the first step. All the unexposed silver is still in the emulsion since you don't fix at this point. Then you do the development in c41 as usual.