Stop Bath.. How important?

[Andrew O'Neill]

Do you use the same batch for both? Someone on APUG once recommended not doing so. Or is that not a problem for you?

Nope. Fresh batch for each session. There have been times when I've changed the batch during a printing session, though. Once it loses that squeaky clean feeling between the fingers.

 

[Don_ih]

Someone on APUG once recommended not doing so.

It's a general recommendation to not share use of stop and fixer between film and paper. But the most practical reason for it is to keep paper fibres from sticking to film. Film stop and fixer should be as clean as possible.

 

[Andrew O'Neill]

I don't use the same stop bath for both film and paper development. They never happen in the same session, anyway... Even at school, I keep them separate.

 

[Mal Paso]

I use film stop bath and fixer for prints and occasionally the other way around and never had a problem. It all comes out in the wash. LOL

It's government's job to daydream situations that don't exist, you are treading on some very jealousy held ground.

Acetic Acid Forever! LOL

 

[cliveh]

I use film stop bath and fixer for prints and occasionally the other way around and never had a problem. It all comes out in the wash. LOL

It's government's job to daydream situations that don't exist, you are treading on some very jealousy held ground.

Acetic Acid Forever! LOL

Fixer is a different dilution for film than prints.

 

[pbromaghin]

Andrew, Don, thank you both for clearing that up.

 

[Sirius Glass]

It is not like stop bath with indicator is expensive and it does prolong the fixer life, besides many film companies spend lots of money on R&D on and about stop bath, so they must have known somethings that will still do not know.

 

[rcphoto]

Somewhat off topic but it's come up at least once in this thread. Am I doing anything particularly wrong using my fixer for film and paper universally? I mix Ilford rapid fixer to 1:4 and use it for both roll film and RC paper fixing. I do check for exhaustion before and after each use/session.

The info sheet from ilford says paper processing manually can be done at either 1:4 or 1:9.

 

[MattKing]

Somewhat off topic but it's come up at least once in this thread. Am I doing anything particularly wrong using my fixer for film and paper universally? I mix Ilford rapid fixer to 1:4 and use it for both roll film and RC paper fixing. I do check for exhaustion before and after each use/session.

The info sheet from ilford says paper processing manually can be done at either 1:4 or 1:9.

Not wrong - assuming you are not re-using the exact same working strength fixer with both - i.e. not using the same bottle of mixed up liquid.
You might be losing some economic benefit with the prints, depending on how much of the capacity you are using up by re-using the fixer.

 

[rcphoto]

Not wrong - assuming you are not re-using the exact same working strength fixer with both - i.e. not using the same bottle of mixed up liquid.
You might be losing some economic benefit with the prints, depending on how much of the capacity you are using up by re-using the fixer.

So I'm still getting proper fixing (I fell like I am), just potentially more costly than it could be?

 

[MattKing]

So I'm still getting proper fixing (I fell like I am), just potentially more costly than it could be?

Correct - and depending how much you re-use it, perhaps not even that.
To pick an analogy that may be really dated in a decade or two, it is like using premium gasoline in a car set up for regular. It doesn't give you any benefit, but it costs you more.
The other way around - using more dilute fixer for both film and RC paper - will cause problems.

 

[koraks]

Fixer is a different dilution for film than prints.

Doesn't have to be though. I often use "print strength" fixer for film. Just ensure total amount of concentrate and fixing time are sufficient. I usually use my fixer one shot, which makes it wasteful to use the film dilution of 1+4. For paper, I make it depend on the paper size and number of sheets I'm fixing; it's often not necessary to use a large volume and I might use a stronger dilution (like 1+6 or so) than typically used for film.

Nothing is carved in stone. 54 pages of discussion proves this.

 

[Don_ih]

many film companies spend lots of money on R&D on and about stop bath

I doubt a penny has been spend on R&D about a bottle of vinegar in many, many decades.

 

[rcphoto]

Correct - and depending how much you re-use it, perhaps not even that.
To pick an analogy that may be really dated in a decade or two, it is like using premium gasoline in a car set up for regular. It doesn't give you any benefit, but it costs you more.
The other way around - using more dilute fixer for both film and RC paper - will cause problems.

Thanks for the reassurance. I typically mix at the 1:4 and reuse fixer until my hypocheck indicates the fixer is spent.

 

[Mal Paso]

Fixer is a different dilution for film than prints.

Nope! Dilution remains the same, times change. Legacy Pro, says right on the package.

So proceeding with the thread drift, Legacy Pro fixer is 700 grams to make one gallon. Kodak F5 fixer requires 2 pounds of Penta Sodium Thiosulfate per gallon. I opened a bag of Legacy Pro and the crystals are rectangular. Could this be Anhydrous Sodium Thiosulfate? Is that the reason for the weight difference? What is the ratio for using Penta versus Anhydrous Sodium Thiosulfate? I have only used Penta when mixing from scratch.

 

[MattKing]

I doubt a penny has been spend on R&D about a bottle of vinegar in many, many decades.

All those funds have been diverted to the marketing budget .
https://www.americanvinegarworks.co...EepZNLwABjrIldEAojBjvsW4sodKDohWYWrT00GGl6NF_

 

[Mal Paso]

I will only use certified organic, sustainably sourced stop bath.

 

[john_s]

Well, an acid stop does help to extend the life of acidic fixers.

I've read this often. However, fixers work well over quite a wide pH range (including moderately alkaline). Does the acid in stop bath really "extend the life" of acid fixers? Actually, neutral fixers last longer in storage than acid fixers, so it might be that the acid could shorten the life of the fixer. (I know it's silver content as much as anything else that is the end of life of fixer. Rinsing the developer out with something, either water or dilute acid, keeps the fixer cleaner which is probably good)

And yes. I do use acid stop for FB paper, in order to avoid possibility of staining.

 

[Andrew O'Neill]

In cases like this, I usually follow the manufacturer's advice...they know more than I on the subject....But, I'm tempted to forego an acid stop, just to see how long my fixer lasts...

 

[Milpool]

In cases like this, I usually follow the manufacturer's advice...they know more than I on the subject....But, I'm tempted to forego an acid stop, just to see how long my fixer lasts...

It’s not going to shorten the life of the fixer.

Historically there were essentially two reasons for fixers being acidic. (1) in the old days hardening during the fixation stage was the norm, and the effectiveness of the usual alum hardener is proportional to acidity. (2) to keep the post-development process from potentially reactivating developer carried over and or retained in the material.

Other than that, acidity serves no purpose and shortens the shelf life of the fixer. All things considered (including odour) a neutral pH fixer is better.

 

[Andrew O'Neill]

Interesting. Thank you. On the topic of neutral fixers, I brought some up a while ago, and it's just not worth it. I always have to order it from afar, and with shipping attached... Besides, a darkroom should smell like fixer

 

[Milpool]

Interesting. Thank you. On the topic of neutral fixers, I brought some up a while ago, and it's just not worth it. I always have to order it from afar, and with shipping attached... Besides, a darkroom should smell like fixer

Well, you can always use Kodak Flexicolor fixer. But yes I agree with you. Despite a neutral fixer being “ideal” in the end I just keep using good old Ilford Rapid Fixer (not to mention good old Kodak stop bath )

 

[john_s]

Interesting. Thank you. On the topic of neutral fixers, I brought some up a while ago, and it's just not worth it. I always have to order it from afar, and with shipping attached... Besides, a darkroom should smell like fixer

Until recently I used Kodak Flexicolor Fixer, but it's harder to source here nowadays. I use Ilford Hypam, and I add a bit of concentrated ammonia solution (sometimes called ammonium hydroxide) to get the pH up a bit. No need to go alkaline though. And, the darkroom still smells of fixer! Just not as strongly.

 

[Ben Hutcherson]

I've made it through page 10 of this thread and am still digesting...

With that said, I'm someone who's always been primarily a D76 guy for film, and Dektol for paper, although I have used HC110 and a few other commercial developers at times(like TMAX for the times I use T-grain films).

I've always done water stops, generally 3 water changes, for film. At the same time, more recently because I've literally not developed film in years and have been backlogged on what needs to be done, I've been doing some larger tanks. I use stainless almost exclusively for 35mm and 120, and in the past rarely used anything other than a 16 oz tank despite having larger on hand, and on the RARE occasion doing 32oz. Lately I've done a few batches in my 64 oz tank, although I'm reluctant to use it if, for no other reason, than I don't have one of the "lift rods"(not sure what they're properly called, but the enormously useful stainless steel rods with a figure 8 on the end that let you lift all the rolls out of the tank). In addition, tanks that size take a LONG time to pour chemistry in and out, especially given that most of my stainless tanks take the same plastic cap, whether 8 oz. or 64 oz. That has me wondering if stop is worth it in these big tanks. To add to that, I'm getting ready to process my first batch of 70mm film using the Mercury Works long roll tnak(modified Patterson tank), which I think they spec at 1.75L. With both of those, I'm reconsidering the value of stop.

Of course when I had an actual darkroom and was printing, I did use stop, primarily because as said paper develops so fast, I always developed prints by inspection, and FB paper especially carries over a lot of solution from one tray to the next. I am a chemist, and have worked with enough acetic acid that I'm not particularly fond of the smell, so when I was printing I opted for a citric acid stop(especially given that it was in an open tray).

I realize, reading through this thread, first of all that acetic acid should normally be used at a low enough concentration where the smell is minimal if not existent especially for film. That and some of the other discussion makes me think I will try it with the next batch of film I develop.

Just as an idle thought, though-the late PE mentioned-if I understand his post correctly-that a pH of around 4.5 is ideal for stop. I'm guessing acetic acid as dilute as specified would probably fall into that range(too early/too lazy to calculate now, especially as it's likely getting into quadratics to calculate pH at those concentrations).

I'm wondering, though-Acetic acid has a pKa of 4.76, which is well within the buffering range of an acetate buffer. I'm wondering if it would be worthwhile to use a buffered stop bath. Of course you'd probably want to use a somewhat higher concentration of acetic acid, and REALLY spitballing but a ~2:1 molar ratio of acetic acid to sodium acetate should get you around 4.5(I'd want to calculate it, or more practically would make a guess and adjust with a pH meter if I were making it). Doing this would obviously make sure that a stop bath would actually work as it should, should avoid problems of the pH being too low, and should last a LONG time. I can't think of an issue with having the acetate ion present, but there also could easily be something I'm missing here.

Does anyone have any thoughts on this?

 

[Sirius Glass]

I've made it through page 10 of this thread and am still digesting...

With that said, I'm someone who's always been primarily a D76 guy for film, and Dektol for paper, although I have used HC110 and a few other commercial developers at times(like TMAX for the times I use T-grain films).

I've always done water stops, generally 3 water changes, for film. At the same time, more recently because I've literally not developed film in years and have been backlogged on what needs to be done, I've been doing some larger tanks. I use stainless almost exclusively for 35mm and 120, and in the past rarely used anything other than a 16 oz tank despite having larger on hand, and on the RARE occasion doing 32oz. Lately I've done a few batches in my 64 oz tank, although I'm reluctant to use it if, for no other reason, than I don't have one of the "lift rods"(not sure what they're properly called, but the enormously useful stainless steel rods with a figure 8 on the end that let you lift all the rolls out of the tank). In addition, tanks that size take a LONG time to pour chemistry in and out, especially given that most of my stainless tanks take the same plastic cap, whether 8 oz. or 64 oz. That has me wondering if stop is worth it in these big tanks. To add to that, I'm getting ready to process my first batch of 70mm film using the Mercury Works long roll tnak(modified Patterson tank), which I think they spec at 1.75L. With both of those, I'm reconsidering the value of stop.

Of course when I had an actual darkroom and was printing, I did use stop, primarily because as said paper develops so fast, I always developed prints by inspection, and FB paper especially carries over a lot of solution from one tray to the next. I am a chemist, and have worked with enough acetic acid that I'm not particularly fond of the smell, so when I was printing I opted for a citric acid stop(especially given that it was in an open tray).

I realize, reading through this thread, first of all that acetic acid should normally be used at a low enough concentration where the smell is minimal if not existent especially for film. That and some of the other discussion makes me think I will try it with the next batch of film I develop.

Just as an idle thought, though-the late PE mentioned-if I understand his post correctly-that a pH of around 4.5 is ideal for stop. I'm guessing acetic acid as dilute as specified would probably fall into that range(too early/too lazy to calculate now, especially as it's likely getting into quadratics to calculate pH at those concentrations).

I'm wondering, though-Acetic acid has a pKa of 4.76, which is well within the buffering range of an acetate buffer. I'm wondering if it would be worthwhile to use a buffered stop bath. Of course you'd probably want to use a somewhat higher concentration of acetic acid, and REALLY spitballing but a ~2:1 molar ratio of acetic acid to sodium acetate should get you around 4.5(I'd want to calculate it, or more practically would make a guess and adjust with a pH meter if I were making it). Doing this would obviously make sure that a stop bath would actually work as it should, should avoid problems of the pH being too low, and should last a LONG time. I can't think of an issue with having the acetate ion present, but there also could easily be something I'm missing here.

Does anyone have any thoughts on this?

I have heard that stop bath and in particular Kodak Stop Bath with Indicator is buffered to keep the pH in the proper range. That and a $50US bill will get you a cup of StarBucks coffee at the airport.