B&W development chemicals

[Bill C]

And who the heck was discussing C-41? Obviously that's a completely different case...

 

No, you miss my point. Here's what you said earlier, "An acetic or other mild acid stop bath, rather than a plain water rinse, preserves the pH of the fixing solution and extends its life..."

 

I am making the case that fixer doesn't have to operate in a lower pH range UNLESS you are using a hardener that requires it. The example to prove this is C-41 fixer, traditionally running in a pH range of roughly 6 to 7. (C-41 fixer is fundamentally similar to a "normal" unhardened rapid fixer, except for the higher pH.) This sort of fixer WITHOUT HARDENER works fine in pH ranges from ~4.5 to 6.5+. I don't have actual experience outside of these ranges, so can't say for certain.

 

If you are not using a hardening fixer (which is mostly not needed anymore), stop bath doesn't really extend the fixer life. It DOES halt development quickly and reliably, which is the main reason for using it, imo. Although I virtually never do, either as amateur or professional (the mainstream professional processes don't use stop baths).

 

I don't think anyone here runs a continuous roller processor machine at home.

 

This website was named "photo.net," not "amateur_processing_at_home.net." (But sometimes I think it should be known as "arrogant.net"). Although I used to post here mainly as an amateur, I had near 30 years of full-time professional photography experience when photo.net was started.

 

I hope I don't come across as an internet-educated newbie. Working with a very large chain outfit, I've been privy to large amounts of confidential information from a number of manufacturers. So I like to make sure that anything I say here can be referenced publicly, or "found out" via simple testing; this is largely to ensure that I don't accidentally spill confidential info.

 

Ps, I've never worked with the modern "superfixes," or whatever.

[tomspielman]

...

I hope I don't come across as an internet-educated newbie.

...

 

No, that would be my role here. :)

[Bill C]

No, that would be my role here. :)

 

Sorry, I didn't mean to be dismissive of you and others in the same boat. It's really a great place to be.

 

I think that perhaps a dart was being thrown at me earlier by the guy who says, "I only have over 40 years darkroom experience." So I was reacting to that.

 

Photo.net has had, over the years, a lot of, shall I say, big talkers, who start out knowing nothing, but within a few months or a year, they can (and do) lecture "knowledgeably" to people who have vastly more experience. Of course, what they are "lecturing" is really just regurgitating what they have read on the internet, which may or may not be true. And to me, that's still ok, as long as they say, "This is what I read..." But when they start acting authoritative, as though it's personal knowledge that they have... then it runs counter to real learning.

 

This is the sort of person I don't want to be mistaken for, but I think that sometimes I am. I say this because occasionally some of the "Wizards of photonet" have felt it necessarily to inform me as to how many years they've been doing this, or where's my bio (they "don't listen to someone without a bio"), or "show us your photos" (we can't tell until we see some of your photos). I ought to name some names and be mean to them, but I don't like to do that. Plus the display of bad temper may live forever on the internet.

 

I think that things should be argued and discussed on their merits or theory, not "because I said so," or because I have so many years of experience. So I never used to give much background. Sometimes I do nowadays.

[tomspielman]

Oh, I wasn't the least bit offended, just cracking a joke.

 

I understand where you are coming from. I value all the knowledge and experience people have here. However, like in any forum, a lot of what is offered is more of an informed opinion rather than fact, I say that because you can often find equally experienced people that will disagree. ;-)

 

I've been in the same line of work for 30 years. In any particular area that someone might be tempted to call me an expert in, I can easily find somebody more expert than me.

[rodeo_joe1]

The MSDS(es) for most of the rapid fixers now on sale shows that their main components are Ammonium Thiosulphate, Sodium metabisulphite (disodium disulphite) and acetic acid. The pH is given as 5.2, which makes them acidic.

 

So it seems to me to be perfectly sensible to preserve that pH by using a mild acid stop bath. Because a short rinse in plain water won't be sufficient to neutralise the developer held in the emulsion. A stop bath also does exactly what it suggests and arrests development almost immediately. A water bath doesn't.

 

I thought this was entirely appropriate to suggest, since Andy, the reviver of this thread, specifically asked about the useable life of fixer. And more specifically for B&W film.

 

I was in no way suggesting that a stop bath was mandatory. Just that it may be beneficial, and certainly not harmful.

 

Nor was I pointing a "newbie" finger at anyone in particular. Just making an observation that there is much useless, misleading or downright incorrect information on the subject of film processing - and nearly every other subject.

 

I wasn't trying to push my experience or knowledge as being in any way superior either. However it did feel like an unwarranted rebuff to my innocent, and informed suggestion to use a stop bath.

Edited June 30, 2017 by rodeo_joe|1

[Bill C]

However it did feel like an unwarranted rebuff to my innocent, and informed suggestion to use a stop bath.

 

Well, I'm sorry if I offended you, but my objection is still there.

 

You recommended an acidic stop bath in preference to water on the basis that this "...preserves the pH of the fixing solution and extends its life." I disagree that acidic stop bath is superior to water for this purpose UNLESS possibly if it is a hardening fixer that needs to be maintained at a low pH. In either case it's probably an insignificant effect, although I haven't done the experiment.

 

Regarding fixer life, one of these "conventional" rapid fixers reaches "end of life" when one of two things happens, 1) it builds up enough silver that you don't want to keep using it (the rate of fixing slows down and it's harder to wash out), or 2) the fixer runs out of sulfite (or bisulfite) ion and starts to come apart ("sulfurizes").

 

There is actually one other thing that could come into play - the build-up of iodide ion in the fixer, coming from many "modern" films, drastically slows down the rate of fixing in a thiosulfate-based fixer. At the place where I worked for a lot of years, we once experimented with regenerating film fixer (desilvering then replace the missing chemicals). But the now too-high levels of iodide made it not feasible.

 

Anyway, based on a great deal of experience, these are the things that affect the life of a fixer, not anything related to the pH, at least within the general range from 4.5 to ~7.0.

 

If you want, I'll give some of my experience, but it'll make me feel like a bit of a bully; I'd rather just stick with the details of the processes.