How much Vinegar to add to water for stop bath?

[Jedidiah Smith]

I've always used vinegar added to water for a stop bath for both my film and prints...but just occured to me that I never really measure the amount. I just dump a tablespoon or two into the tray for prints, or a bit less in a 1000ml bottle for film.

Anyone know if there is a specific amount that I should be using? (I know, why change what has been working? I just want to make sure I'm not losing out on better results.)

Thanks for your time,
Jed

 

[Nick Zentena]

What kind of vinegar? You can do the math.

If you've got 5% vinegar and find a formula that calls for 28% stop math then you need 28/5 times the amount and of course less water.

http://www.jackspcs.com/sb1.htm

Shows about 50ml of 28% so you'd add 28/5*50 or 280ml of 5% to get the same end result.

Lots more then a tablespoon.

 

[MattKing]

I am just working from memory here.

IIRC working strength stop bath is approximately 3% acetic acid. The commercial vinegar is 5% acetic acid. Therefore, 600 ml of vinegar, diluted to one liter, will give you one liter of working solution vinegar with 3% acetic acid.

A teaspoon won't do it, although if your water is alkaline, it will help slightly.

Matt

 

[Ed Sukach]

Stop baths are *usually* 1% acetic acid. Common white vinegar is usually 5% acetic acid - so dilite the white vinegar: 200ml vinegar and 800ml water - one part vinegar to four parts water; five parts total, one of which is 5% acetic acid = 1%.

 

[Bruce Osgood]

I used to schlep home giant bottles of white vinegar to dilute 1:5 (1+4) until I did a cost comparison and Kodak Indicator Stop Bath turned out to be cheaper.

 

[25asa]

Vinegar? Who can stand that stuff?

Chardonnay 1+10 single shot.

 

[Jedidiah Smith]

Thanks for the info. I will use the 200ml to 80mml water, then. I never realized there was an actual formula for stop bath - in fact, I always thought it was an optional step, and so I just kind of added some vinegar in with the water because I read somewhere that it worked.

I really appreciate all of your time, and pointing out that there was indeed a formula to follow! I may look into getting indicator stop bath; I just never have because it has to ship UPS, and that is more expensive to Alaska. All my film, developers and fixer I just have sent by USPS Priority Mail.
Thanks,
Jed

 

[srs5694]

Shipping to Alaska would probably throw these results, but by my calculation, vinegar stop bath, at 280ml per liter of working solution, is $0.31 per liter, whereas Kodak's indicator stop bath is $0.19 per liter of working solution. This is based on the cost of a local store-brand vinegar (plus tax) vs. a 1-pint bottle of the Kodak stop bath from Adorama (plus $2 shipping).

If you can find a local source of an appropriate acid (citric and acetic are common), you can make a stop bath from it pretty cheaply. Bromcresol purple is one possible indicator agent, but I don't know offhand where to get it. I've also heard of making an indicator dye out of cabbage juice, but I don't know the details offhand. A Web search might turn up something.

 

[Gerald Koch]

In the first place you really don't need indicator stopbath unless you a going to make a very large number of prints. I personally have never been able to exhaust a stopbath during single session. I know that some will say "I save my stopbath between sessions to save money." You shouldn't really save stopbath and attempt to reuse it later since bits of paper and other crude builtd up in it during use.

Use your nose as a pH meter. If the bath still smells like vinegar then its still acidic enough to work.

Not all white vinegar is 5%, some brands are only 4%. Check the label before diluting.

The amount of acetic acid used in a stopbath depends on its intended purpose, whether it is for films or papers.

 

[Nick Zentena]

Some vinegar is 7%. Around here it's fairly easy to buy distilled malt vinegar for much less then stop. It's not even close on price if you go by normal store prices. If you stock up on vinegar when it's on sale the stop gets that much more expensive.

I've bought 4ltires of 7% pickling for $1. 2 16oz bottles of Kodak 28% would be $14.

 

[catem]

I use white table vinegar but don't use very much - maybe a couple of capfuls in a 12 x 16 tray. The smell and feel in the water is strong enough, and it works for me - that way it works out cheaper in the end than stop bath - but I'm not that keen on stop anyway and the alternative for me would be to use water only.

Cate

 

[ElrodCod]

There's a lot of fuzzy math in this thread. Sam's Club (and other warehouse clubs no doubt) sells two gallons of white 5% vinegar for $3.06. My math makes that about 31¢ per gallon of working solution. By far the cheapest option....cheap enough to use it as a one shot.

 

[MattKing]

One other minor point - as the (stock solution) indicator stop bath is much more concentrated than vinegar, it takes up much less storage space in the darkroom. If volumes are moderate, and space is at a premium, this may make the stop bath more appropriate.

Stop bath seems to keep forever - I am still using up some Ektaflo stop bath that is probably 35 years old! I certainly wouldn't want to try 35 year old vinegar.

IMHO, unless volumes are very high, the cost of stop bath is about the lowest cost that we might incur, and therefore issues of effectiveness, efficiency and convenience should determine the choice, rather than cost per darkroom session.

Matt