Oxygenation of used Flexicolor Bleach

[Bob-D659]

May be a somewhat dumb question, but would it hurt to give a bottle of used bleach a shot of pure oxygen from my handy dandy oxygen cylinder? It sits in my shop right next door to the darkroom.

 

[chamon88]

If you what to reuse the flexicolor bleach you need to add 60ml per liter of bleach regenerator.

 

[Mr Bill]

I'm guessing that it won't hurt, but may not help too much either. I've only aerated with air, but if the bubbles are too large, the actual "contact area" (and time) may not be enough to get good use out of your air. My experience has been with spargers in fairly fast cine processors (continuous).

I personally wouldn't even try oxygen, but if I had to, I'd start with a very small bleach sample, just in case the reaction somehow gets out of hand. It's possible that there might be bad effects with carried-over developer (maybe forming tar?); I don't know. Again, I wouldn't even bother trying this.

Do you have reason to suspect that you need aeration? Or a way to measure the effect? Just curious.

ps: I only worked with the earlier version of the bleach, the one based on FeEDTA. I'm not sure that the later versions follow exactly the same rules, but I suspect so. Chamon88 recommends using regenerator, perhaps this chemically oxidizes the bleach? (in the older version of bleach, it did not).

 

[markbarendt]

Won't hurt, it can actually help in normal circumstances.

Of course it depends on how used the bleach is.

 

[mtjade2007]

If you reuse C-41 bleach and it some how is exhausted you can always rebleach again with another batch but fresh bleach. To reduce the impact of PH changes carried over by developer you can set up two bleach steps. One with an old batch of bleach and the other with a fresh one. If the first batch is so exhausted the bleaching will be completed by the 2nd batch.

To oxygenate bleach I usually fill half a bottle of it, cap the bottle then shack it vigorously for 10 seconds. It will form a lot of bubbles but the bubbles will disappear quickly by shaking the bottle again but only lightly. You can repeat it one more time if you want. The bleach is usually recovered quickly this way for me.

 

[Bob-D659]

I was reading about shaking a half full bottle of bleach just before use, and was just wondering out loud if doing an air purge with oxygen for short term storage would be a good thing(TM).

I've got a 1/2 liter that has processed 4 rolls, maybe I'll give it a try and see what happens.

 

[Mr Bill]

I probably wasn't too clear earlier, when I said it [aeration via O2] might not help too much. I meant this: if bleach already has enough aeration, then more won't help. The C-41 process seems to have a pretty good margin for error, that's why I asked my previous questions.

Your plan to shake a small amount of bleach in a large bottle is an easy way to get some aeration. I suspect that just pouring it in and out of your tank, or whatever, is already enough.

 

[Mike Wilde]

Sometimes it is months between the use of bleach for c-41.

I actually use e-6 bleach for my c-41 work , mainly becuase it was found for free at a reuse shelf at my local HHW depot, and thus was too good a deal to pass up.
(On the other hand I use c-41 strength fix for e-6).

I have a dedicated fish tank 'air stone' that I poke into a bleach jug and let a fish tank air pump gurgle it overnight, if the belach has not been used for a long time.

 

[Rudeofus]

Instead of blowing air into a bottle, would it work to just add small amounts of H2O2 to the bleach and let it stand for a day or two? The waiting period would make sure that all H2O2 is gone and one could do that after a few bleach runs when no further runs are planned right away.