Alkali vs Acid Fixers

[Paul Kinzer]

I feel a bit odd posting this: I am an absolute newbie to film development, so have little confidence in the theoretical knowledge I've attained through research and reading. But much of that reading is based on books that are often out of date, so I wonder if some of the information in them might be, too.

Anyway, while exploring for the right chemicals for my foray into B&W film development, I came across the Photographer's Formulary page describing their Art Fix alkali fixer. From what it describes, acid fixer seems like something that should just no longer be used. I won't go into all the details they do, but the page seems worth a read. They sure make it seem like alkali fixer is just a simpler, better answer.

I'd really be interested in what folks with experience have to say about this.

[Michael R]

Be careful what you read. What's written in the linked page ranges from true, to partially true, to it depends, to not true.

Neutral/alkaline fixers can have a few benefits vs equivalent acidic fixers depending on formulation, how acidic the acid fixer is, hardening vs non-hardening, regular vs rapid, etc. Without getting into too many details, the main benefit of non-acidic fixers - generally speaking - is that they will tend to wash out of photographic materials (particularly fiber-based papers) faster than acidic fixers. However it really depends on which acidic fixer and alkaline fixer you are comparing. Non-acidic fixers can also be more stable and have higher capacities, but again it depends on the formulation.

Note Art Fix is not a rapid fixer. If you want to use one of Formulary's fixers, I'd first suggest TF-5, which is a neutral rapid fixer and pretty much the state of the art as far as commercially available products go. Try TF-4 if you want an alkaline rapid fixer.

[LabRat]

Michael is right, "beware of information"...

First, hypo based fixers do vary quite a bit, so look up each formula to see the differences... Acid fixers were to neutralize alkaline carryover from the developer (to stop combined fixing/development that could happen at the same time if a proper stop bath was not used), provide the optimum pH for the clearing action, provide a proper environment for the addition of hardening agents, and a consistent fixing action (as the fix became more alkaline)...

But I may confusing this with ammonium thiosulfate based (rapid) fixers that I make/use... (I prefer them as they fix faster and well, last long, soak into the paper bases less, work cleaner (don't stain/oxidize), and are much easier to wash out of materials in shorter wash times at different washing temps...)

All of this has been extensively tested many years ago by the research departments of the mfgs, so what you find in the old photo reference books is still valid...

Steve K

[Paul Kinzer]

Okay, thanks! I obviously still have a lot to learn.

I'm trying to come up with simple, relatively clean, and fairly inexpensive developing chemicals. At this point, speed is not really an issue for me. I'd like something as foolproof as possible, so something that takes time seems like an okay idea. According to the link in my OP, modern films do not require hardener, which was news to me (and not mentioned in my reading, unless I missed it). The link also said that plain water is all that's needed for a stop bath with the Art Fix, which also seemed like a simplification.

I am thinking about using divided D76, and the Art Fix seemed like a good match for it (but what do I know?). I'm never going to be more than an occasional LF photographer, and I'll be developing film even less often; maybe 25-50 sheets this year. I don't, at this point, plan to do any printing with chemicals; I'll be sticking to scans for now. I'm also thinking of using an 8x10 Unidrum for developing two sheets of 5x7 Ilford FP4 at a time.

Is there any reason that I should not do what I just described? By that I mean, two different things. First: will it not work for some technical reason? And/or, Second is there a better way, based on my priorities (simplicity, cost, and cleanliness)?

I feel a bit like I'm cheating by asking up front, 'Tell me just what to do!' On the other hand, there are so many choices (which is a good and cool thing that I may eventually try my hand at experimenting with) that I'd like to just get started right the first time. I know that 'right' is purely subjective, but I'd like to get started without messing up, and if the way /I start can be a way that works long term, so much the better.

[Doremus Scudder]

Paul,

First the fixer question: Alkaline fixers, as mentioned, wash out more quickly. This is of primary importance with fiber-base papers. That said, there are a lot of slightly-acid and neutral fixers out there that work just fine. The real thing you should be aware of is the difference between sodium thiosulfate (hypo) fixers and ammonium thiosulfate (rapid) fixers. The former take much longer to fix and may not fix some modern films (e.g., TMax) completely. Rapid fixers are significantly faster and are recommended by the manufacturers for both TMax and Delta films. I think most of us now use a rapid fixer in some incarnation or other. My fixer(s) of choice is Ilford Rapid Fixer (or Hypam). It (they) are very slightly acid at working dilutions and come in convenient liquid concentrates. TF-5 would be another recommendation. It is neutral pH.

As for your suggested work flow related to your question, "is there a better way, based on my priorities (simplicity, cost, and cleanliness)?" I would question a couple of things.

First, if you plan on processing only occasionally, I'd try to keep things simple and use everything you can from liquid concentrates that have a long shelf life. Why divided D-76? You have to mix it from powder, which means you have a stock solution with a shorter lifespan. Plus you have two developing steps, which is really unnecessary for 99% of cases. A developer like HC-110 or Ilford IlfotecHC comes in a concentrate that will last for years. If you mix just what you need for a single session directly from the concentrate, the concentrate will last years. There are other developers like this too, e.g. Rodinal or, my standard, PMK, but the two mentioned above will give results very, very like D-76.

The same with stop and fix. I use an Ilford citric-acid stop bath and mix up just what I need for a single session from the concentrate. It lasts for years. Ilford Rapid Fixer (or any rapid fixer that comes in a liquid concentrate, for that matter) can also be diluted right before use to make the volume you need for a single session. Fixer concentrate in a partially-filled container has a shelf-life of 6 months to a year. So, why mix working solutions and have them sitting around in bottles taking up space and getting too old to use?

And, although I won't tell you what to do, I will give you some recommendations based on my 30+ years of darkroom experience and reading and research

Do use a stop bath. It stops development quickly and reliably, prepares the neg for the fix and is simply more reliable and simpler than a water bath.

Go for a rapid fixer (i.e., ammonium thiosulfate based). The Art Fix fixer you mention is a sodium thiosulfate (conventional/slow) fixer, and seems to be rather finicky and fragile (a stop bath will ruin it...) Note that alkaline TF-4 and neutral TF-5, both formulated by Kodak engineer Ron Mowrey - PE here on the forum, are designed to work with a conventional acid stop bath and are rapid fixers. I'd recommend either of those along with the Ilford products I mentioned before Art Fix.

And ditch the fancy-schmancy divided developer if you're just starting out. Use a liquid concentrate that lasts a long time if you only develop occasionally.

Best,

Doremus

[Paul Kinzer]

Thanks, Doremus!

I freely admit that I don't know what I am doing. The ideas I had were based on conclusions I reached after the (fairly detailed but limited) research I've done. But since I don't really have a base of experience to draw from, I'm happy to be corrected. I had not really thought about the advantage of liquid concentrate. I'm especially appreciative of specific recommendations. They give me a direction for more research.

I must say that, even though I have yet to put any film into chemicals, I am having a fascinating time reading and thinking about all the possibilities. I cannot think of many other pursuits that have such a strong mix of absolute and precise empirical actions that are used in pursuit of a wide range of subjective artistry.

Again, many thanks!

Paul

[Paul Kinzer]

So, now that Ive been appropriately shot down, what would be a good starting place for me? I hope to do some 5x7 photos with Ilford FP4. Developing in a constantly turning 8x10 Unidrum seems like something that will work in my space and with my skill set. Concentrated liquid that keeps a long time seems like an excellent idea. Would Ilfotec, an acid stop bath (which one?) and TF-5 be a good combination. How about Rodinal? How would it be different from the Ilfotec if used with what I've described? Are there downsides to any of these (staining, smell, toxicity, finickiness)?

Maybe I should do some more reading. I have a couple of more books on the way. But specific suggestions will make my reading more focused, so I'd be grateful for more!

[jvo]

paul,

with all due respect, i'd suggest you do some processing rather than reading.. you have enough info from your reading, and the replies here... have some fun!

jvo

[axs810]

Paul,

First the fixer question: Alkaline fixers, as mentioned, wash out more quickly. This is of primary importance with fiber-base papers. That said, there are a lot of slightly-acid and neutral fixers out there that work just fine. The real thing you should be aware of is the difference between sodium thiosulfate (hypo) fixers and ammonium thiosulfate (rapid) fixers. The former take much longer to fix and may not fix some modern films (e.g., TMax) completely. Rapid fixers are significantly faster and are recommended by the manufacturers for both TMax and Delta films. I think most of us now use a rapid fixer in some incarnation or other. My fixer(s) of choice is Ilford Rapid Fixer (or Hypam). It (they) are very slightly acid at working dilutions and come in convenient liquid concentrates. TF-5 would be another recommendation. It is neutral pH.

As for your suggested work flow related to your question, "is there a better way, based on my priorities (simplicity, cost, and cleanliness)?" I would question a couple of things.

First, if you plan on processing only occasionally, I'd try to keep things simple and use everything you can from liquid concentrates that have a long shelf life. Why divided D-76? You have to mix it from powder, which means you have a stock solution with a shorter lifespan. Plus you have two developing steps, which is really unnecessary for 99% of cases. A developer like HC-110 or Ilford IlfotecHC comes in a concentrate that will last for years. If you mix just what you need for a single session directly from the concentrate, the concentrate will last years. There are other developers like this too, e.g. Rodinal or, my standard, PMK, but the two mentioned above will give results very, very like D-76.

The same with stop and fix. I use an Ilford citric-acid stop bath and mix up just what I need for a single session from the concentrate. It lasts for years. Ilford Rapid Fixer (or any rapid fixer that comes in a liquid concentrate, for that matter) can also be diluted right before use to make the volume you need for a single session. Fixer concentrate in a partially-filled container has a shelf-life of 6 months to a year. So, why mix working solutions and have them sitting around in bottles taking up space and getting too old to use?

And, although I won't tell you what to do, I will give you some recommendations based on my 30+ years of darkroom experience and reading and research

Do use a stop bath. It stops development quickly and reliably, prepares the neg for the fix and is simply more reliable and simpler than a water bath.

Go for a rapid fixer (i.e., ammonium thiosulfate based). The Art Fix fixer you mention is a sodium thiosulfate (conventional/slow) fixer, and seems to be rather finicky and fragile (a stop bath will ruin it...) Note that alkaline TF-4 and neutral TF-5, both formulated by Kodak engineer Ron Mowrey - PE here on the forum, are designed to work with a conventional acid stop bath and are rapid fixers. I'd recommend either of those along with the Ilford products I mentioned before Art Fix.

And ditch the fancy-schmancy divided developer if you're just starting out. Use a liquid concentrate that lasts a long time if you only develop occasionally.

Best,

Doremus

Wait you can use an acid stop bath with tf-4? I was under the impression a water stop bath is better for tf-4. Mind educating me on this?

Edit/ say if you do use an acid stop bath with tf-4 does that do anything to the wash cycle times or life of the fixer?

[LarsAC]

Keep things simple at the beginning until you achieved consistent handling of all steps and can roughly control / judge relevant parameters such as developer time, dilution, etc. Well established developers have the advantage that you will get quite good feedback in case of difficulties.

Trying to save some cost is a reasonable goal, but your learning curve will be better with good quality material as it may be difficult to distinguish processing issues frim material fault.

Lars