Stop bath: citric acid or "regular"?

[Barry Kirsten]

Likewise I have had no problem with growth in citric acid stop bath. Here is a quick pic of a batch I made at least 12 months ago.

 

[Patrick Robert James]

I prefer citric acid. I get the citric acid at a local health food store, but it is really cheap on ebay. A scoop or two in the tray and I'm good to go. I haven't used regular stop bath in many years. I never liked the whiff of acetic acid you get with Kodak stop bath. I just mix it and throw it away after the session. Plus the citric acid doesn't bother my lungs. Big plus... After a few hours in the darkroom I don't feel like a smoker.

The whole citric acid grow stuff means nothing to me since I toss it. Why you would bother to keep 5¢ worth of stop bath.....

 

[RattyMouse]

Am I the only one who uses diluted vinegar as a stop bath???

 

[williaty]

Stop bath is reusable, I store and use stop bath until the indicator starts to turn purple, like the instruction manual explains. Just RTFM and you will find that you can indeed reuse and store stop bath. If you screw the top on the bottle you will not smell the stop bath. Just keep one batch for film and another for prints.

A lifetime's worth of stop made from bulk citric acid powder will cost less than the bottle used to store it between sessions. I don't see the economy. I use less than 1 cent of citric acid per printing session.

I'm not worried about the smell of the acetic acid during storage. It's just disgusting the whole time you're working with it regardless of whether you're processing film in a tank or paper in a tray. Same reason I absolutely hate the fact that balsamic vinaigrette became trendy at restaurants.

 

[hacked - sepiareverb]

Never tried citric acid, I use Kodak indicator stop for films and home mixed acetic acid for printing. I store & re-use the film stop till the indicator tells me to dump it, and just dump the print stop when cleaning up. If it ain’t broke why fix it.

 

[Wayne]

The idea of storing used stop bath just boggles my mind! I'd never heard of such a thing before today.

I switched from acetic to citric acid stops for all my work because I HATE the smell of acetic acid. They work just fine and the powder is so cheap there's no hardship throwing it out at the end of a printing session or once a tank of film has been processed.

There's not much hardship in pouring it back in the bottle either. And my darkroom sink doesn't drain into a sewer or septic, so I don't dump chemicals in it. Only rinse water does down the drain, as a matter of principle and good habit

 

[RalphLambrecht]

Is there such thing as a difference in quality? I wanted to try out the citric acid based and wondered how good it actually works. Thanks.

citric acid works just fine.

 

[RalphLambrecht]

15g of citric acid/l of water makes a good stop bath; no indicator required; just renew frequently.

 

[lantau]

It simply is more convenient to store the stop bath and also the final rinse. I'd have to get the acetic acid from the stock room, and mix it, rinse the measuring cup afterwards. Not terrible but an interruption in the the work flow. Especially since I use it only for C41, where I have all solutions ready to go anyway. For b/w I stop with water and with ECN2 I have to use dilute sulfuric acid. I'm not getting the bottle of conc acid from the basement storage every single time I want to use that one. It's not going to go bad either.

As for the smell, I have no problem with it. Not with ammonia either. Both are pleasant to me, only at high concentration will they burn in the nose, obviously.

 

[Mainecoonmaniac]

15g of citric acid/l of water makes a good stop bath; no indicator required; just renew frequently.

That's what I use for stop bath. It's odorless and cheap.

 

[jim10219]

Am I the only one who uses diluted vinegar as a stop bath???

Nope. That's what I use. I use it for cleaning things (it's environmentally safe and is safe for cleaning up around animals) and making pickles as well. It's also great for removing battery acid from old electronics that had leaky batteries. Mix it with baking soda, and you've got a super powerful cleaner (and drain clog remover), and a fun science experiment for the kids. In the darkroom, I use it as a stop bath and a contrast booster for cyanotypes. I don't even use an indicator, I just use fresh and pour the whole stop bath out and make another tray full if I'm going to be doing a lot of prints. It's cheap. It serves multiple uses, and I'm going to own it anyway, so it takes up zero space.

So yeah, I'm with you. Why would anyone use anything else?

 

[Pioneer]

Am I the only one who uses diluted vinegar as a stop bath???

No. 1.5 vinegar to 1 water and it lasts a long time. Easy to get and very inexpensive. I use it in tanks and in trays.

Love the smell of vinegar in the morning.

 

[MattKing]

Am I the only one who uses diluted vinegar as a stop bath???

I have used it - out of necessity.
But it isn't my preference, due to smell, size and cost.

 

[Sirius Glass]

That's what I use for stop bath. It's odorless and cheap.

Stop bath with indicator is cheap. Film costs more. Color development chemicals cost more.

 

[RattyMouse]

No. 1.5 vinegar to 1 water and it lasts a long time. Easy to get and very inexpensive. I use it in tanks and in trays.

Love the smell of vinegar in the morning.

I make about a 10% dilution of vinegar in water and throw it away after use. I used to save it when I lived in China but back then I processed a hell of a lot more film than I do now. These days I can't even finish off a bottle of fixer before it goes bad. I've gone from shooting 10-15 rolls per week to 1-2 rolls per month. Not much throughput for sure.

 

[wyofilm]

Some vinegar into a 1 gal. jug of water. Pull some from jug for paper (use plain water for film). Toss at the end of the day.

 

[Wayne]

That's what I use for stop bath. It's odorless and cheap.

do you get slime, or only use it once? Am I the only one who stores it without slime?


Edit: Oh, I just saw Barry's post above so I'm not alone.

 

[Sirius Glass]

do you get slime, or only use it once? Am I the only one who stores it without slime?


Edit: Oh, I just saw Barry's post above so I'm not alone.

In over six decades I have never had a problem with slime in stop bath.

 

[Wayne]

In over six decades I have never had a problem with slime in stop bath.

But you are using commercial SB, which some people think has a biocide. I'm not sure if it does though.

 

[RalphLambrecht]

In over six decades I have never had a problem with slime in stop bath.

me neither

 

[RattyMouse]

But you are using commercial SB, which some people think has a biocide. I'm not sure if it does though.

If there is no biocide, how to explain the lack of bacteria? All hydrocarbons are sources of nutrition for bacteria. In an aqueous environment, with food, bacteria grow prodigiously.

My company just recently formulated a product based off of calcium acetate in water. It didnt have a shelf life of 3 days. Fungus and bacteria grew to visible levels over a weekend. Reformulated with a biocide, it has a shelf life of 6 months or longer.

 

[Wayne]

If there is no biocide, how to explain the lack of bacteria? .

What bacteria? Only certain people are having problems with slime. I don't know what the problems is in their cases but not everyone using plain citric acid stop has that problem. Clearly then, lack of noticeable growth is not proof of the presence of a biocide. However, absence of any growth in anyone's commercial SB would be strongly suggestive of one.

 

[Sirius Glass]

What bacteria? Only certain people are having problems with slime. I don't know what the problems is in their cases but not everyone using plain citric acid stop has that problem. Clearly then, lack of noticeable growth is not proof of the presence of a biocide. However, absence of any growth in anyone's commercial SB would be strongly suggestive of one.

Golly, Wayne, some people smoke for decades and never get lung cancer, so using your logic we should all start smoking. Did you know that it is possible to jump off a 50 story building and not die? Should we put that on our bucket lists too?

 

[wyofilm]

calcium acetate

Back in my research lab the one reagent we could never reliable keep from growing crap was Ca acetate. I believe one of problems was that even high purity ca acetate carried microbial impurities in the solid product.

 

[Wayne]

Golly, Wayne, some people smoke for decades and never get lung cancer, so using your logic we should all start smoking. Did you know that it is possible to jump off a 50 story building and not die? Should we put that on our bucket lists too?

Your post does not logically follow from mine. It happens in Ilford stop bath too. http://www.film-and-darkroom-user.org.uk/forum/showthread.php?t=10783 "I use Ilford Stop Bath diluted 1:19 (the regular version with the yellow indicator). It is stored at a reasonably low temperature, usually < 15 deg. C. I have found in the past that a jelly-like substance can form."

So don't buy Ilford (using your logic. You seem to have misunderstood my point). The point is there's no need for a biocide, even if someone has trouble with growth in citric acid its dirt cheap to dump and replace and plenty of people have no trouble at all.