Maintaining Bleach

[Kuby]

Hello,

I recently purchased some Bleach iii Replenisher in an attempt to maintain the PH level of my bleach.

I also purchased some PH Test strips so I could monitor where the PH is at.

Some questions:

A) What PH level is the bleach supposed to be at? I'm using a working solution from an F2 kit. The bleach is green.

B) I can't seem to get the PH test strips to work. Since the bleach is green, it seems to just turn the test strips green, and the results the strips show do not match any of the possible results. Are there specific strips I should be using, and if so can someone direct me to them?

C) Is there a general rule of thumb for the amount of replenisher to add? (Per roll of film, maybe?)

Thanks.

Edit: I probably should have stated that I'm using a jobo cpp2

 

[Rudeofus]

Bleach III should be somewhere between pH 4.2 and 4.5. Since it is buffered, you may be able to dilute it 1:10 and then try pH indicator strips. pH should not change much with dilution, but ability to cover pH indicator strips with bleach color should be much reduced. Any pH differences between full strength and dilute bleach should be neglectible compared to pH resolution of indicator strips.

The amounts of replenisher to add per roll processed should be written down somewhere in the replenisher instructions or in the process manual.

 

[Anon Ymous]

A cheapo ($10) pH meter comes with a suitable calibration buffer (pH 4 in this case) and is far more useful than these pH indicator strips.

 

[Kuby]

I feel like the more I dig into this the more I just get confused. I have thus far been unable to find a definitive guide on how to use a maintain kodak flexicolor bleach iii. Part of my problem is probably that I'm looking for a guide with regards to home use in a jobo machine. Maybe this doesn't/shouldn't matter.

I started with a working bleach solution from an F2 kit, and now have purchased kodak flexicolor replenisher CAT # 660 0258. It now dawns on me that I actually have no idea how to use it in conjunction with my working bleach solution, and I haven't managed to find a great online guide to assist me.

I'd also like to know how the replenisher works in conjunction with a regenerator.

And the more I scour the internet, the more I seem to confuse myself. Can anyone bring me up to speed or point me in the right direction?

 

[Kuby]

Update:

It seems to me like what I should be doing is taking the replenisher, mixing it with a starter (to create a second working solution), and using that to replenish my original working solution. Would this be a good approach?

From what I can tell the regenerator is used for "overflow" which one does not get a lot of from a jobo system. So it doesn't seem necessary.

Seems like I can't go too far wrong with this second-working-solution-as-replenisher approach. The starter is pretty cheap. My only question would be how much to use per roll of film.

 

[Rudeofus]

AFAIK the original purpose of starter and replenisher was to mix a working solution from starter+replenisher first, then after each roll replace a certain amount of working solution with replenisher. Kodak's Bleach III was not originally intended for minilabs, not for home processors with Jobos, and the instructions and process manuals reflect that. In your case the best course of action is to get a cheap pH meter as suggested by Anon Ymous, measure pH of fresh bleach, then after each film roll replace working solution with replenisher until pH is back to original value. Once you sort of know how much to add, you could then ditch the pH measurement and just use that amount fro future runs.

 

[Kuby]

AFAIK the original purpose of starter and replenisher was to mix a working solution from starter+replenisher first, then after each roll replace a certain amount of working solution with replenisher. Kodak's Bleach III was not originally intended for minilabs, not for home processors with Jobos, and the instructions and process manuals reflect that. In your case the best course of action is to get a cheap pH meter as suggested by Anon Ymous, measure pH of fresh bleach, then after each film roll replace working solution with replenisher until pH is back to original value. Once you sort of know how much to add, you could then ditch the pH measurement and just use that amount fro future runs.

Nice. This is the exact answer I was looking for. Thank you!

One thought: wouldn't it eventually all be replenisher at some point, if you did this indefinitely? Intuitively it seems like eventually you'd need to add more starter.

 

[Anon Ymous]

I think you will find this document (page 2) interesting. It gives answers to some pH specific questions.

 

[Kuby]

I think you will find this document (page 2) interesting. It gives answers to some pH specific questions.

Nice. Thanks!

 

[Rudeofus]

One thought: wouldn't it eventually all be replenisher at some point, if you did this indefinitely? Intuitively it seems like eventually you'd need to add more starter.

As film gets bleached, the working solution changes: bromide is used to form Silver Bromide, pH goes up as Ferrous PDTA is oxidized back to Ferric PDTA (through aeration). Replenisher just restores the used working solution to something closely resembling its original composition.

 

[Kuby]

As film gets bleached, the working solution changes: bromide is used to form Silver Bromide, pH goes up as Ferrous PDTA is oxidized back to Ferric PDTA (through aeration). Replenisher just restores the used working solution to something closely resembling its original composition.

Awesome. I think I got all the answers I was after. Very much appreciated.

 

[MattKing]

Replenisher is intended to just get your working bleach solution back to where you were before you changed things by bleaching a roll of film in it.
It is important to also remember that when you use a working solution in a replenishment regime, the process of moving the film through the working solution also removes some of the working solution - through chemical reaction, and solution carry forward. In some cases, you also have to remove a set volume of the used stuff as well..
So some things get used up or removed, and then some things get added back (replenished) when you add the replenisher.

 

[Mr Bill]

Hi, I've spent a significant part of my working life overseeing working replenished color neg/print systems, albeit older, prior to bleach iii. I would suggest that you at least start out by the book, which would be the Kodak Z-131 publication - the third section covers "rotary-tube processors."

In this doc, for rotary processors, they state in bold type, "Do not attempt to replenish or regenerate used bleach solution. Reuse it only to the batch capacity; then discard it." Now, I have NO REAL KNOWLEDGE what is the reasoning behind this, although I could probably make some guesses. Personally, I don't see any fundamental problem with replenishing, etc., but I'm not gonna recommend that you disregard the Kodak recs.

And the more I scour the internet, the more I seem to confuse myself. Can anyone bring me up to speed or point me in the right direction?

Z-131 is basically the end user's bible, but it is more along the line of a cookbook. Fundamentally, here's how a replenished bleach works. The maker, Kodak, has specifications for each chemical component in the "working tank," which is what you use for processing (these specs are not known to the general public, as far as I know). As film is processed, the bleach gradually gets diluted as wet film comes in. So to counteract this, the replenisher must be "over-concentrated" compared to the working tank. Additionally, some of the bromide is used up in proportion to how much silver has to be bleached, so the replenisher needs a slight higher concentration of bromide. Additionally there will be a slight amount of evaporation that has to be accounted for. Also, the bleach must be kept adequately "oxidized" while it is in use, although this is more of a "process requirement," rather than a replenisher formulation issue. (In high-volume commercial machines, it is standard to continuously bubble air through the bleach while processing.)

So in general, the replenisher is formulated based on the aim rate (volume of replen per "film") and some assumptions on 1) average mount of developer carried in, 2) average amount of bleaching to be done, and 3) evaporation. There is one additional thing it must do, and that is to keep the pH of the working tank in spec. In the standard process, high-pH developer is carried directly into the bleach, so the replenisher must have a pH value lower than the tank solution in order to counteract this (see CIS-61, as linked by Anon Ymous, to see the pH difference between working tank, pH 4.75, and replenisher, pH 4.50).

With this info on the differences between tank solution and replenisher, you can see roughly what has to happen with the "starter solution;" essentially it is necessary to dilute the replenisher, and to raise the pH. But in practical terms, it's really not all that critical, unless maybe if the replenisher is on the low side of pH spec (I don't know how touchy this is).

Too much info? If so, just stick with Z-131 or other chemical maker's instructions. My wild guess about the "do not replenish" instructions are that the Jobo processor bleach carry-in is too unpredictable - it might be developer, stop bath, or water, and the volume might vary a lot, depending on who the user is. (In my experience, Kodak docs have mostly been conservative, protecting the user from mistakes, so they may have just taken the position, "don't replenish it;" but I'm just guessing.

 

[Mr Bill]

I'd also like to know how the replenisher works in conjunction with a regenerator.

To continue on with what I've just said, above, we're almost always gonna end up with a surplus of bleach. Now this may not be obvious, but consider that the film entering the bleach is always wet, meaning that the bleach volume increases. But when film LEAVES the bleach, it is also wet, so that very roughly the bleach tank keeps the same volume. So the tendency is that the bleach "volume" increases by about the same amount as the replenisher volume - if you use up a liter of bleach replenisher then your tank volume wants to increase by about a liter, more or less.

So what will become of the extra bleach? Well, in a normal processor the tank is a certain size, and any extra bleach will leave the tank via an "overflow" pipe. Perhaps I should point out that since the "overflow" comes out of the tank, it is, therefore, chemically identical to the tank solution. Since the "iron" in the bleach is one of the most expensive components in the whole C-41 setup, it seems a waste to throw it away. One way to save some of this waste bleach is... to add whatever chemicals are needed to turn it back into replenisher. This is what the "regenerator" mix does. Then you use it as replenisher.

The bottom line is that by using bleach replenisher, then collecting and regenerating the bleach overflow, the amount of waste becomes very small. (We still lose some bleach due to carry-out as a result of wet film leaving the tank, plus some overflow.)

At this point, you may wonder, well, if this is such a great thing to do, why doesn't everyone do it? Well, basically, I guess mostly 'cuz they don't know how (it has a different set of skills than being a photographer). And... maybe the savings aren't worth the trouble. One other thing to point out is that "savings" are largely influenced by the amount of carry-out (and carry-in). You want to get these amounts as low as possible, which means... SQUEEGEES - at both the developer exit AND the bleach exit. Since the huge majority of posters here seem to be scared to death of squeegees, well maybe it doesn't make sense. I dunno, never worked out any numbers; high volume finishers USE squeegees (minilab processors can do the same thing by squeezing the film between rollers). If you don't use developer-exit squeegees, the tank solution will get overly diluted, that is, the chemical concentrations get below spec. Then, if you collect the overflow, and regenerate it, then the replenisher will be somewhat diluted. This will lead to the tank solution being even more diluted than before, in a sort of vicious circle. (If you want to do this, you really want some lab test equipment as well as some know-how, in order to keep things on an even keel, so to speak.)

So you can see why Kodak might have wanted to head off these problems by saying, "dont try to replenish bleach in a rotary-tube processor."

 

[Rudeofus]

I guess the main difference between processing in minilab tank vs. rotary processor is the amount of liquid vs. number of films processed at once. A single film running through a 10 liter tank doesn't much change liquid composition, whereas two films processed simultaneously in 250 ml means big changes. The best way to approximate a minilab like process with a Jobo would therefore consist of a large batch of working solution (let's say 1 liter or more), using only what's needed in the tank and pouring the liquid back into the big container after each run, then replenish the big container. Not sure whether this gives acceptable results for color developer, but at least for bleach and fixer it should work just fine.

 

[Mr Bill]

I guess the main difference between processing incompare tank vs. rotary processor is the amount of liquid vs. number of films processed at once.

No, I think that in the specific case of replenished C-41 bleach, the amount of residual chemical (stop bath or water, etc.) from the prior step is the biggest issue. I'm gonna take a guess of well over double the equivalent carryover as compared to a "moving-film" machine with efficient squeegees. This is a pretty big deal in the world of replenishment.

The standard replenishers are pretty much designed around a squeegee'd film, where carryover rates are low and very consistent. With something like a Jobo processor, not only is the film not squeegeed, but both the film reels and inside of the tank (drum?) hold on to some liquid; I imagine that every tank and reel combination varies, and the actual drain time is another factor.

 

[Kuby]

To continue on with what I've just said, above, we're almost always gonna end up with a surplus of bleach. Now this may not be obvious, but consider that the film entering the bleach is always wet, meaning that the bleach volume increases. But when film LEAVES the bleach, it is also wet, so that very roughly the bleach tank keeps the same volume. So the tendency is that the bleach "volume" increases by about the same amount as the replenisher volume - if you use up a liter of bleach replenisher then your tank volume wants to increase by about a liter, more or less.

So what will become of the extra bleach? Well, in a normal processor the tank is a certain size, and any extra bleach will leave the tank via an "overflow" pipe. Perhaps I should point out that since the "overflow" comes out of the tank, it is, therefore, chemically identical to the tank solution. Since the "iron" in the bleach is one of the most expensive components in the whole C-41 setup, it seems a waste to throw it away. One way to save some of this waste bleach is... to add whatever chemicals are needed to turn it back into replenisher. This is what the "regenerator" mix does. Then you use it as replenisher.

The bottom line is that by using bleach replenisher, then collecting and regenerating the bleach overflow, the amount of waste becomes very small. (We still lose some bleach due to carry-out as a result of wet film leaving the tank, plus some overflow.)

At this point, you may wonder, well, if this is such a great thing to do, why doesn't everyone do it? Well, basically, I guess mostly 'cuz they don't know how (it has a different set of skills than being a photographer). And... maybe the savings aren't worth the trouble. One other thing to point out is that "savings" are largely influenced by the amount of carry-out (and carry-in). You want to get these amounts as low as possible, which means... SQUEEGEES - at both the developer exit AND the bleach exit. Since the huge majority of posters here seem to be scared to death of squeegees, well maybe it doesn't make sense. I dunno, never worked out any numbers; high volume finishers USE squeegees (minilab processors can do the same thing by squeezing the film between rollers). If you don't use developer-exit squeegees, the tank solution will get overly diluted, that is, the chemical concentrations get below spec. Then, if you collect the overflow, and regenerate it, then the replenisher will be somewhat diluted. This will lead to the tank solution being even more diluted than before, in a sort of vicious circle. (If you want to do this, you really want some lab test equipment as well as some know-how, in order to keep things on an even keel, so to speak.)

So you can see why Kodak might have wanted to head off these problems by saying, "dont try to replenish bleach in a rotary-tube processor."

Hey Bill, thank you so much for this interesting and very detailed reply, and apologies that it took me til now to get back to you. You filled in blanks that I didn't even know were missing. This is the kind of information that I feel is quite important to know, but equally challenging to find. Even though it is written out in manuals and such, it's written with some tacit knowledge in hand, and not for those of us coming in blind.

It's a little bit disheartening to know that from a rotary processing standpoint, using replenished bleach is considered a "no-no". From what you wrote out here, I'm still trying to determine an "optimal" approach to maintaining bleach for my situation. Before I delve into that though, one point: I haven't been using water or a stop bath between the developer and the bleach, because I read that for the bleach to work properly, developer needs to be present. From my own quite limited experience, this has seemed to get me better results, so I'm inclined to ditch the stop/water bath from here on out. Do you have any knowledge or thoughts in this regard?

With that in mind, it seems the best approach I can take is to a) try to completely drain the developer before introducing the bleach, b) monitor the bleach with test strips, and add replenisher to bring it back into proper PH range after every use, and c) purchase some starter to occasionally make new batches of working solution. This latter point would add to the overall cost over time but also help to play it safe.

Would you agree with the above approach?

 

[Mr Bill]

I haven't been using water or a stop bath between the developer and the bleach, because I read that for the bleach to work properly, developer needs to be present. From my own quite limited experience, this has seemed to get me better results, so I'm inclined to ditch the stop/water bath from here on out. Do you have any knowledge or thoughts in this regard?

Hi, no I don't have practical knowledge in this area, but I can give some thoughts. First, my experience has been with an earlier version of C-41 bleach that ran at a much higher pH. Now with THAT bleach (iron-EDTA vs the more recent PDTA versions, I think) we had to be careful with the (continuous) processor setup - good developer exit squeegees and submerged "turbulator bars" blowing against the film as it entered the bleach. (These are continuous "cine" machines runners perhaps 50 feet/minute, so the carryover developer might otherwise "pool" where it is carried in to the bleach tank.) Otherwise we would get some "streaking" due to development not being halted fast enough. So because of this experience I would be real careful about doing the same thing, straight from developer into bleach, with a Jobo, but perhaps the lower pH of the newer bleach iii takes care of things. I would tend to rely on either the docs plus experience of other Jobo users here, OR do my own testing.

Regarding possible replenishment, any time you go against the Kodak recs, you're pretty much on your own. But again, I don't see any fundamental reason against replenishment, except for the substantial carryover of developer (or water, or whatever). I should probably say that I'm not really a fan of Jobo-type machines, but IF I were considering this, I'd start out with some rough cost estimates, replenished vs not, just to see if it was worth my time. If it seemed like it MIGHT be worthwhile, or perhaps I just felt like playing with things a bit, I might experiment.

Since I've worked with this sort of thing before, I'd probably estimate the Jobo carryover rates first, and then compare to a "standard" sort of carryover rate. As I recall, there's a table in the Kodak Z manual with a typical carryover for a squeegee'd continuous processor. You can look that up, along with the recommended replenishment rate, and this shows you how much replenisher is needed to counteract the dilution effect of the carryover. From that, you could estimate how much replenisher ought to be used at higher carryover rates, such as with a Jobo.

Then the question would be: how much equivalent carryover does the Jobo have? If you have a decent scale you could roughly measure this. Ideally you'd weigh the dry (loaded with film) Jobo tank, then weigh again after the developer has been drained (and all water on the outside is wiped off). Of course you wouldn't want to actually interrupt the process cycle like this, but if you weigh it near the end after draining wash water, you probably won't be far off. To convert weight to volume, 1 mL water weighs very close to 1 gram. (Actual developer is a bit heavier than water by a factor equal to the specific gravity.) So you shouldn't be able to estimate the required replenishment rate for the Jobo machine, with its larger amount of carryover, and see how the costs work out. Then you can decide if it's worth it to you.

 

[Mr Bill]

Ok, I DID look up some rates, and made some calcs, detailed below for anyone who wants to wade through it:

Z-131 part 2 has a table, "Continuous and Roller-transport Processors (with efficient squeegees)," giving a carryover rate of 10 mL per square foot of 35mm film. Converting to a 135-36 roll is about 6 mL per roll. The bleach replen rate per table 2-2 (9.2 mL per linear foot ) converts to about 48 mL per roll. A simplified way to look at this is that, unless I messed something up, the replenishment rate has to be about 48/6 = 8 times the developer carryover rate.

Now if you look at table 3-3, "Capacity of Unreplenished Solutions..." (which, being in part 3, is for the "rotary-tube" type processor, such as Jobo), you can see that the capacity is about 8 rolls per liter (the table says 4 rolls, for developer, but the footnote says that the bleach rate is double this). Anyway, 1 liter divided by 8 rolls is equivalent to 125 mL per roll.

So the pertinent thing this reveals is that the breakeven point for a replenished system is when the carry-in rate reaches about 15 mL per roll - about 2 1/2 times the "efficient squeegee rate," then the necessary bleach replen rate reaches about 125 mL per roll, same as the unreplenished capacity.

In short, this may explain why Kodak says to not replenish bleach in a rotary-type (aka Jobo) type processor. If the equivalent developer carryover is about 15 mL per roll (135-36), then the necessary bleach replenishment rate (by my rough calcs) is about 125 mL, which is effectively the same bleach usage rate as the "unreplenished capacity" in the Z manual. In other words there would be no cost benefit to replenishing bleach. If anyone with a Jobo machine and a decent scale accurate to at least a gram wants to, they could measure the carryover rate as in my prior post.

Note that I'm just looking at the bleach as a bath that gets diluted, ignoring the pH and need for aeration, etc. I don't want to get into this too much due to the possibility that I might be steering someone wrong, but I'll make guesses on request.

 

[Kuby]

Ok, I DID look up some rates, and made some calcs, detailed below for anyone who wants to wade through it:

Z-131 part 2 has a table, "Continuous and Roller-transport Processors (with efficient squeegees)," giving a carryover rate of 10 mL per square foot of 35mm film. Converting to a 135-36 roll is about 6 mL per roll. The bleach replen rate per table 2-2 (9.2 mL per linear foot ) converts to about 48 mL per roll. A simplified way to look at this is that, unless I messed something up, the replenishment rate has to be about 48/6 = 8 times the developer carryover rate.

Now if you look at table 3-3, "Capacity of Unreplenished Solutions..." (which, being in part 3, is for the "rotary-tube" type processor, such as Jobo), you can see that the capacity is about 8 rolls per liter (the table says 4 rolls, for developer, but the footnote says that the bleach rate is double this). Anyway, 1 liter divided by 8 rolls is equivalent to 125 mL per roll.

So the pertinent thing this reveals is that the breakeven point for a replenished system is when the carry-in rate reaches about 15 mL per roll - about 2 1/2 times the "efficient squeegee rate," then the necessary bleach replen rate reaches about 125 mL per roll, same as the unreplenished capacity.

In short, this may explain why Kodak says to not replenish bleach in a rotary-type (aka Jobo) type processor. If the equivalent developer carryover is about 15 mL per roll (135-36), then the necessary bleach replenishment rate (by my rough calcs) is about 125 mL, which is effectively the same bleach usage rate as the "unreplenished capacity" in the Z manual. In other words there would be no cost benefit to replenishing bleach. If anyone with a Jobo machine and a decent scale accurate to at least a gram wants to, they could measure the carryover rate as in my prior post.

Note that I'm just looking at the bleach as a bath that gets diluted, ignoring the pH and need for aeration, etc. I don't want to get into this too much due to the possibility that I might be steering someone wrong, but I'll make guesses on request.

Hi Bill,

Thanks for doing this. And apologies for my extremely late reply. I've gone ahead and decided to just start using my bleach 1-shot. While the idea of reusing bleach is heartwarming, I'm somewhat obsessively concerned over my negatives being as good as they can be, so I've decided to heed your advice with regards to the matter, and the truth is that the increase in cost is still very moderate in comparison to other things in my life. I think I'll be spending somewhere around $1 on bleach per roll of film developed, which I can afford.

I know there are many in this group who reuse their bleach endlessly, but much like my transition away from blix kits to Kodak Flexicolor chemistry, my results seem to have improved dramatically since using everything one-shot, so I'll keep on keeping on.

I do have one final question for you though (or anyone out there who might know the answer!) - Would it make more sense for me to be using Kodak Flexicolor SM bleach as opposed to Bleach iii regen + starter? I noticed that SM bleach is what comes with the F2 kit (which is what I originally purchased). I assume that it's basically Bleach iii + starter, though, so perhaps it would be simpler for me. Only issue I'm noticing is that it's out of stock at UniquePhoto and BH has it as special order, so maybe I don't have a choice in the matter.

Thanks as always,
Michael

 

[Mr Bill]

I do have one final question for you though (or anyone out there who might know the answer!) - Would it make more sense for me to be using Kodak Flexicolor SM bleach as opposed to Bleach iii regen + starter?

Hi, I don't know for sure; perhaps someone else can answer this?

My fuzzy recollection about SM chemicals was that they were mainly just a "plugin" sort of chemical package that was only intended for minilab machines that had the correct hookup. (May have also been highly concentrated to minimize frequency of changing.)

My way of thinking is that this may have been a way to minimize employee training requirements. In the US the OSHA "Hazard Communication Training" (aka "Right to Know") was required for any employee where it was reasonably foreseeable that they MIGHT possibly come into contact with the chemicals. If the equipment could be designed so such contact could not happen, the training and record-keeping requirements would not be necessary for all employees, only for maintenance techs, etc. But this is just my own guesswork. (At the outfit where I worked, I think that our one-time minilab chain had been sold off prior to SM chems.)