D-23 and Stop Bath

PicklesFrog · Apr 4, 2024

Hi all,
Made up a batch of D-23 a few days ago, and starting doing test strips for development.
This is my first time using D-23 and the Darkroom Cookbook told me to use a acid stop bath. So I made a citric acid stop bath, and after i pour it out into another beaker (sink is in the other room) it strongly smells of vinegar. Is this normal?

Its really irritating my nose and I'm not too sure if this is normal. I used 15g of citric acid in 1L water by the way.

Thanks

PicklesFrog · Apr 4, 2024

I'm also using TF-4 Rapid Fixer, not sure if that counts for anything as well.

koraks · Apr 4, 2024

PicklesFrog said:
So I made a citric acid stop bath, and after i pour it out into another beaker (sink is in the other room) it strongly smells of vinegar. Is this normal?

There's no way a citric acid stop bath will start smelling like vinegar. I think you're mistaking something else for a vinegar smell. What does happen is if you use a fairly strong stop bath after a high-sulfite developer like D23, is that sulfur dioxide will be formed. At a low pH (<4.0 IIRC), sulfite will break down into sulfur dioxide. There's plenty of sulfite in D23 and some of the developer is on your film & reels. I assume you're mistaking the pungent smell of sulfur dioxide with a vinegar smell - they really are quite different, but both are often experienced as pungent and 'nasty'.

You can fix this in a few ways:
1: Don't use an acid stop bath. At risk of starting yet another lengthy diatribe about yes/no stop bath, your film will really come out fine if you use only a water bath instead of an acetic acid stop bath.
2: Use a buffered citric acid (or other non-odorous) stop bath. You're not the first one to run into this problem and @Steve Goldstein solved it like so: https://www.photrio.com/forum/threads/buffered-citric-acid-stop-bath.201215/
3: Use...acetic acid! It's quite likely that you will find a weak (0.5% or so) acetic acid stop bath to be acceptable in terms of its smell. Since the pH will be higher, but still low enough to act as a proper stop bath, there will be no (or very little) sulfur dioxide gas being formed.

fophem · Apr 4, 2024

TF-4 is an alkaline fixer, it's better to avoid the stop bath and stay alkaline all the way. A water rinse between the developer and fix bath is sufficient. Especially if you use D23 at 1+1 dilution, your development time should be around 10-14', no need for a precise stopping action.

koraks · Apr 4, 2024

fophem said:
TF-4 is an alkaline fixer, it's better to avoid the stop bath and stay alkaline all the way.

Not necessarily, and arguably, the opposite. Using an alkaline fix without a stop bath carries the risk of dichroic fog. You'll probably get away with it most of the time. I do agree that the precise stopping action is not very relevant here, which is why I suggested a water 'stop' as an alternative. One or two water rinses instead of an acetic stop will also get the job done.

The benefits and/or drawbacks of an alkaline fixer for film are of course yet another point of debate and a possibly contentious topic.

fophem · Apr 4, 2024

Yes, stopping before a (so called) alkaline fixer is debatable. I've never noticed any problem but never precisely tested neither, that's why I've turned back to acid rapid fixer now. Keep it safe and simple...

koraks · Apr 4, 2024

Yes, agree; nothing wrong with acid fixer, either, especially for film.

Ian Grant · Apr 4, 2024

Ron Mowrey (PE) who was involved with TF--4 recommended a stop bath with alkali fixers as there's a high chance of Dichroic fogging causing uneven stains. This was something he had observed during testing.

Ian

pentaxuser · Apr 4, 2024

PicklesFrog said:
This is my first time using D-23 and the Darkroom Cookbook told me to use a acid stop bath.

Thanks

Yes that's fine Could it be that you are particularly affected by the smell from citric acid? Have you used it before and if so was there any problem then?

You can just use a water bath consisting of several washes and dumps before fixing as an alternative to an acid stop bath. It's what I have done for many years now. Not because of the smell but simply from habit. I have access to a tap in the darkroom and filling and dumping with water is just as easy for me.

An acid stop bath stops any development instantly whereas water only stops nearly all development on the first wash and dump and then on subsequent washes and dumps reduces the developer activity to zero

pentaxuser

koraks · Apr 4, 2024

pentaxuser said:
the smell from citric acid

Citric acid is absolutely perfectly odorless.

pentaxuser · Apr 4, 2024

koraks said:
Citric acid is absolutely perfectly odorless.

Well the range of answers I get from various sources is from odourless to slight smell Yes I have never been able to smell it but others who have a strong sense of smell or stronger than mine presumably might be able to smell something

What I cannot work out is if the OP has used citric acid before( hence my question) and if so whether this is the first time he has got a vinegar smell from it. Nor is it possible to work out from what he says why apparently pouring it from one beaker to another has made it smell of vinegar This suggests that the smell arose not from making it in one beaker but from pouring it into another

It suggests that something changed between making it and then pouring it into another beaker. Only he can provide us with what changes might have taken place

It's a puzzle that needs more information from the OP to arrive at a probable cause

pentaxuser

koraks · Apr 4, 2024

@pentaxuser I feel that in #2 I've given a perfectly adequate and plausible explanation as well as several solutions. I don't think there's "a puzzle" here.

Pioneer · Apr 4, 2024

I us a lot of D-23. I use a dilute solution of 1 part of cheap white vinegar from the grocery store (which is already pretty dilute) and 3 parts water as my stop bath and have never experienced a strong vinegar odor when I stop development. YMMV but my nose could be broken by now.

Actually I use that stop bath for just about all my developing except for when I am stopping Efke 25 and Adox CMS 20. Then I just use a couple of water rinses with distilled water.

PicklesFrog · Apr 4, 2024

koraks said:
There's no way a citric acid stop bath will start smelling like vinegar. I think you're mistaking something else for a vinegar smell. What does happen is if you use a fairly strong stop bath after a high-sulfite developer like D23, is that sulfur dioxide will be formed. At a low pH (<4.0 IIRC), sulfite will break down into sulfur dioxide. There's plenty of sulfite in D23 and some of the developer is on your film & reels. I assume you're mistaking the pungent smell of sulfur dioxide with a vinegar smell - they really are quite different, but both are often experienced as pungent and 'nasty'.

You can fix this in a few ways:
1: Don't use an acid stop bath. At risk of starting yet another lengthy diatribe about yes/no stop bath, your film will really come out fine if you use only a water bath instead of an acetic acid stop bath.
2: Use a buffered citric acid (or other non-odorous) stop bath. You're not the first one to run into this problem and @Steve Goldstein solved it like so: https://www.photrio.com/forum/threads/buffered-citric-acid-stop-bath.201215/
3: Use...acetic acid! It's quite likely that you will find a weak (0.5% or so) acetic acid stop bath to be acceptable in terms of its smell. Since the pH will be higher, but still low enough to act as a proper stop bath, there will be no (or very little) sulfur dioxide gas being formed.

Maybe I am mistaking it, thanks for the info.

Will the calcium scum mentioned in the darkroom cookbook be an issue with using a water bath? No3 seems tempting but now I don't want any gasses being released

PicklesFrog · Apr 4, 2024

pentaxuser said:
Yes that's fine Could it be that you are particularly affected by the smell from citric acid? Have you used it before and if so was there any problem then?

You can just use a water bath consisting of several washes and dumps before fixing as an alternative to an acid stop bath. It's what I have done for many years now. Not because of the smell but simply from habit. I have access to a tap in the darkroom and filling and dumping with water is just as easy for me.

An acid stop bath stops any development instantly whereas water only stops nearly all development on the first wash and dump and then on subsequent washes and dumps reduces the developer activity to zero

pentaxuser

I've used a citric acid solution in other labs just not in a darkroom. It smells only slightly like "something" but its not extremely bad.

PicklesFrog · Apr 4, 2024

pentaxuser said:
Nor is it possible to work out from what he says why apparently pouring it from one beaker to another has made it smell of vinegar This suggests that the smell arose not from making it in one beaker but from pouring it into another

i also sniffed my tank after stopping and nearly died because of the smell haha... should've listened in chemistry to waft instead of putting my nose in.

PicklesFrog · Apr 4, 2024

fophem said:
TF-4 is an alkaline fixer, it's better to avoid the stop bath and stay alkaline all the way. A water rinse between the developer and fix bath is sufficient. Especially if you use D23 at 1+1 dilution, your development time should be around 10-14', no need for a precise stopping action.

Thats fair, I am using d76 times. only tested two strips each with different agitation methods. Will do more to see what works for me

Paul Howell · Apr 4, 2024

Is Photographers Formulary stop acid or alkaline?

koraks · Apr 4, 2024

Paul Howell said:
Is Photographers Formulary stop acid or alkaline?

An alkaline stop bath is an oxymoron. It's technically possible (and indeed commercially available, at least one product AFAIK) to have a neutral stop bath.

PicklesFrog said:
Will the calcium scum mentioned in the darkroom cookbook be an issue with using a water bath?

It may; you could always do a citric acid bath after the fixer to get rid of any calcium scum. This won't release any sulfur dioxide, since the developer won't carry over into the citric acid rinse. Or first see how it goes without the acid.

PicklesFrog said:
No3 seems tempting but now I don't want any gasses being released

You mean HNO3 / nitric acid? No need to go there, really. Nasty stuff. And you'd still run into sulfur dioxide releases if you simply substitute nitric for citric acid.

PicklesFrog · Apr 4, 2024

koraks said:
You mean HNO3 / nitric acid? No need to go there, really. Nasty stuff. And you'd still run into sulfur dioxide releases if you simply substitute nitric for citric acid.

No, I meant your third option of using acetic acid stop bath

pentaxuser · Apr 4, 2024

PicklesFrog said:
i also sniffed my tank after stopping and nearly died because of the smell haha... should've listened in chemistry to waft instead of putting my nose in.

If I have understood your statement correctly then it sounds as if you experienced no smell when you diluted it to the correct dilution and poured it into the developing tank after dumping the developer but when you poured the stop bath out into another beaker was it then that you got the smell and nearly died. Was the tank lid still on so all the stop smell had to exit from the small hole in the tank lid and did you breathe deeply with your nose over the tank hole

I simply ask for more details because if the sequence was as I think it was and your sense of smell for citric acid is particularly acute then that might explain it

Here's a test to try. Pour some more diluted citric acid into the tank with the lid on, agitate it for about 30 secs maximum then pour it out. Place your nose over the hole in the lid. Is the smell the same? If it is then that suggests it is the citric acid you smell but if it is different then it might be koraks' explanation that describes what you smelled

It does seem strange that your previous experience with citric acid was that the smell not extremely bad as you said below

"I've used a citric acid solution in other labs just not in a darkroom. It smells only slightly like "something" but its not extremely bad."

pentaxuser

Andrew O'Neill · Apr 4, 2024

I've used citric acid stop baths for years. I've never noticed a vinegar smell...

PicklesFrog · Apr 4, 2024

pentaxuser said:
If I have understood your statement correctly then it sounds as if you experienced no smell when you diluted it to the correct dilution and poured it into the developing tank after dumping the developer but when you poured the stop bath out into another beaker was it then that you got the smell and nearly died. Was the tank lid still on so all the stop smell had to exit from the small hole in the tank lid and did you breathe deeply with your nose over the tank hole

I simply ask for more details because if the sequence was as I think it was and your sense of smell for citric acid is particularly acute then that might explain it

Here's a test to try. Pour some more diluted citric acid into the tank with the lid on, agitate it for about 30 secs maximum then pour it out. Place your nose over the hole in the lid. Is the smell the same? If it is then that suggests it is the citric acid you smell but if it is different then it might be koraks' explanation that describes what you smelled

It does seem strange that your previous experience with citric acid was that the smell not extremely bad as you said below

"I've used a citric acid solution in other labs just not in a darkroom. It smells only slightly like "something" but its not extremely bad."

pentaxuser

yes, no smell as i diluted it.
yeah after I developed the film for however long i needed to, i dumped out the developer and poured in the stop bath. only i sniffed a little not deep breath and got shocked by the smell, threw myself back and all.

I think koraks' explanation is correct as this morning (and currently) my throat hurts, and my nose kinda hurts to breath in. those are symptoms shown on a quick search for "sulfur dioxide inhalation symptoms"

I should really do these things in a well ventilated area... lesson learned.

koraks · Apr 4, 2024

PicklesFrog said:
No, I meant your third option of using acetic acid stop bath

Oh, LOL! Right, see how that goes and if perhaps the acetic acid smell is tolerable. In a weak dilution, it may not be too bad. Smells a bit like a salad dressing that way!

PicklesFrog said:
my throat hurts, and my nose kinda hurts to breath in.

Yeah, sort of a prickly sensation. Some people are (much) more sensitive to this than others. I do get that prickly sensation the moment I smell it, but generally no after-effects. But it's an irritating gas for sure.

markbau · Apr 4, 2024

koraks said:
Citric acid is absolutely perfectly odorless.

Maybe to you, I've used a citric acid stop for quite a while now and it is definitely the dominating smell in my darkroom when I'm printing. I actually don't mind the smell and would never go back to acetic acid and what it used to do to my mucus membranes. Citric acid in powder form doesn't really have a smell but when mixed with water (I add 3 teaspoons to 1 litre) it has a distinctive smell to me.

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