Reusing C-41 Bleach

[Photo Engineer]

In this case, I would use about 7 minutes in the bleach and fix. If the fix time must be adjusted upwards, then match the bleach time to it. Use it at 100F.

This is a poor substitute for the real thing in view of the difficulty in removing all of the silver from C41 films. Frankly, I would not do it unless it was an emergency. Also, the capacity is going to be about 1/4th that of the real things.

PE

[anikin]

Thank you PE. Your advice is as always invaluable!

[iranzi]

All of the bleaches use up any halides present and so not only must you shake it to aerate it, but you must add some Bromide or Chloride. Also, the pH tends to drift up or down depending on whether you use no stop or use a stop, so the pH must be reset to its original value.

Remember: Aerate, add some Ammonium Bromide or Ammonium Chloride and adjust the pH with Acetic Acid 28% or Ammonium Hydroxide 28% as needed.

For the red bleaches, you should also add about 1 gram per liter of EDTA Acid, and neutralized with Ammonium Hydroxide. For Bleach III you should do the same but there is no real source for the NTA.


PE

PE, thanks so much for this!
Can you clarify a couple of things: if i understand correctly Bromide/Chloride can be added to both red and III bleaches, plus the EDTA acid to the red bleaches only (or to both bleach types as well?)
What amounts of Bromide/Chloride should be used?
Also, I didn't get the last bit about the NTA. Is it ok to do without it? Thanks

[Photo Engineer]

You are correct in all of your comments.

There is no hard and fast rule for the amount of halide to add due to the question of seasoning. The amount of film determines this. Usually it only takes a tiny amount though.

NTA should be used (its full name is on the ingredient list of bleach III). It forms a different Iron III complex than EDTA which is stronger and has a lower COD and BOD in the effluent. Without a small excess, brown stain can begin to build up. This can be minimized by using a stop bath.

PE

[EdSawyer]

Just to resurrect this topic, I have now used one 5L batch of Bleach III 5 or 6 times (225+ rolls of 120, give or take), regenerating it with Flexicolor bleach regenerator after the first time. How many more times can I get away with this? Indefinitely? The negs still look great, though I don't have a densitometer or control strips to test with, just by eye and by printing them on RA4 paper. Are there any visual indications of the bleach going bad or other simple way to test it after regeneration?

It's nice that Bleach III can be regenerated at least 5 or 6 times, it saves a lot on the cost of C-41 at home, given that bleach is the hardest item to come by, and the most expensive to buy and ship.

thanks,

-Ed

[Photo Engineer]

There are control data plots on the Kodak web page that show what happens when the bleach goes bad. Basically you will find colors become desaturated, grain goes up and Dmin goes up.

PE

[EdSawyer]

Thanks PE! Any thoughts on the Kodak Regenerator and how many times one might be able to use it, offhand? Finding some way to test the pH - would that be helpful in diagnosing if it's still good? I read the docs on the regenerator, but they don't mention a capacity or lifetime for the bleach. They basically show a closed-loop system though, schematically, where the overflow bleach is regenerated and becomes replenisher. The biggest thing they talked about was evaporation, which is probably a non-issue in my case.

Most appreciated,

-Ed

[AlbertZeroK]

Thanks PE! Any thoughts on the Kodak Regenerator and how many times one might be able to use it, offhand? Finding some way to test the pH - would that be helpful in diagnosing if it's still good? I read the docs on the regenerator, but they don't mention a capacity or lifetime for the bleach. They basically show a closed-loop system though, schematically, where the overflow bleach is regenerated and becomes replenisher. The biggest thing they talked about was evaporation, which is probably a non-issue in my case.

Most appreciated,

-Ed

Interesting, I wonder how pumping air into bleach also effects this. I have E-6 and C-41 bleach in buckets (with lids) for my Phototherm. Every night for an hour, a little air pump (from a fish tank) pumps air into the bleach. I have not done enough processing of color to exhaust the bleach it's self (5L), so not sure it's even an issue yet...

[Photo Engineer]

The bleach is reduced by oxidizing Silver metal in film. This is repaired to an extent by bubbling air through the bleach. However, the pH changes and some ingredients are used up such as Sulfite, Halide, Ammonia, and ETDA (or NTA depending on bleach type).

Therefore, the exhausted chemicals must be replenished, the Iron must be oxidized and the pH must be repaired. The amount depends on how you handle your particular process. Kodak gives guidelines and I suggest that you go by them. They will work with a recirculation system or a batch operation if you adjust things correctly.

PE