how much do I dilute vinegar to make stop bath?

[angrykitty]

I'm not a math person soooo....

I've got a 5% acidic plain white vinegar solution... stop is 2% acidic... how many parts water do I add to bring it down to 2%?

I'm a retard I know. Thanks in advance though.

 

[adm]

as an example, I'll use 1 L of dilution.
5% of 1 L is 50mL of vinegar
(0.05 * 1000 = 50)

you need to bring that total volume up to:

0.02 * x = 50
x = 50/0.02
x = 2500 mL

in short, look at your current volume of dilution,
and add 1.5 times that volume in water

 

[MattKing]

Say you want to end up with one litre of 2% working strength stop. That means that you have 20 millilitres of acetic acid.

If you start out with vinegar with 5% acid, there are 5 millilitres of acetic acid in every 100 millilitres. So to get 20 millilitres of acid, you need to start out with 400 millilitres of vinegar. Then you dilute it by adding enough water (600 ml) to bring the volume up one litre.

The formula: volume of vinegar needed is equal to total volume of stop desired times concentration of acid in stop divided by concentration of acid in vinegar

or 1000 ml x 2%/5% = 400 ml vinegar

Hope this helps

 

[Dave Martiny]

Both adm and MattIng are correct. Another way of saying it is that the ratio of water to vinegar should be 3 to 2; that is, use 3 parts of water for every 2 parts of vinegar.

Regards,

Dave

 

[fschifano]

or 1000 ml x 2%/5% = 400 ml vinegar


I'd probably want to be a little more clear and express it as 1000 x (.02 /.05) = 400. It's too easy to forget that the % sign means the number is shifted two decimal places to the right. If you forget that, the whole thing falls apart and you wind up with 2500 ml. of vinegar. Could be very confusing to the uninitiated.

 

[Colin Corneau]

OK I'll ask it.

Why would you want to do this. Stop bath is ridiculously cheap, available and easy.

 

[fschifano]

I thought the same thing too. If you work the numbers, anyone can see that using a proper indicating stop bath actually costs LESS than using white vinegar as a stop bath. But the OP did claim to be math challenged...

 

[RobertV]

..... or use Citric Acid, 15g/ltr. Less smell, also cheap.

 

[hrst]

OK I'll ask it.

Why would you want to do this. Stop bath is ridiculously cheap, available and easy.

Vinegar IS the stop bath! You are right, it is ridiculously cheap, available and easy!

 

[MaximusM3]

I think water is even cheaper..and it works

 

[jgcull]

Just water? Water alone will work fine? What, then, is the advantage of using a stop bath or vinegar?

 

[MattKing]

Just water? Water alone will work fine? What, then, is the advantage of using a stop bath or vinegar?

Nooooooooo!!!!

(there was a url link here which no longer exists)

 

[RobertV]

To spare you to read this whole thread:
Water will not stop but delay and dilute the developing process. Depending how you are working both methods are done. I prefer the acid stop, 1,5% - 2% without any problem on all emulsions (even Efke 25 which I am using) in combination of almost all developer types.

The time period of development is exact and consistent. 15g/ltr. Citric Acid (1,5%) will not kill my budget, even when I am ordering at the factory

Especially at short developing times the accuracy can be even measured with a densitometer (log D density measurement in the negative).

But it's up to every one how they want to treat their own negatives .......

 

[fschifano]

Nooooooooo!!!!

(there was a url link here which no longer exists)

Here we go again.......

(Thanks for posting the link to that recently beat to death thread.)

 

[panchro-press]

Thank you for asking the question, Colin. These stop-bath questions are beginning to drive me CRAZY!

Dave

 

[Ken Nadvornick]

These stop-bath questions are beginning to drive me CRAZY!

Yes, but at least the OP was not again asking about efficacy. It was just a simple can-you-help-me-out question about how to dilute it correctly. And as usual, several posters jumped right in to offer some helpful assistance with that. APUG is really, really good that way.

Ken

 

[Mike Pieper]

OK I'll ask it.

Why would you want to do this. Stop bath is ridiculously cheap, available and easy.

White distilled vinegar is much more available, which is why I use it. It's available at your closest grocery store. Try ordering Kodak Indicator Stop Bath from B&H. You can't, because they won't (or can't) send it through the mail.

 

[mrred]

I think water is even cheaper..and it works

Water is NOT a stop bath. It does not stop the developer from working. It just flushes it away. if you use water, you are rinsing not stopping......

 

[desertrat]

I've used diluted vinegar, and it works fine, with this caveat: You must filter your homemade stop bath. The white vinegar looks clean and clear to the naked eye, but if you pour a little in a glass, get it swirling, hold it up to the light and look at it with a magnifier, there's loads of crud swirling around. And that crud sticks tenaciously to you negatives, ruining them. At least that's what happened to me the first time I did this. Ruined a roll of 35mm B/W film. After it's filtered, it seems to work fine. Maybe some brands of white vinegar out there are already filtered, but it would be best to check.

 

[angrykitty]

I thought the same thing too. If you work the numbers, anyone can see that using a proper indicating stop bath actually costs LESS than using white vinegar as a stop bath. But the OP did claim to be math challenged...

The photo store is a 40 minute uphill upwind bike ride away, or a 60 minute bus ride, and I'm not in the mood for heavy cardio or crackheads (besides the fact that bus fare costs more then the vinegar). The grocery store down the street sells a gallon of vinegar for $2.00, plus I'm all stocked up on everything else, so it's kinda silly to go through all that just for stop... besides, I haven't tried it yet... I'm curious.

 

[angrykitty]

I've used diluted vinegar, and it works fine, with this caveat: You must filter your homemade stop bath. The white vinegar looks clean and clear to the naked eye, but if you pour a little in a glass, get it swirling, hold it up to the light and look at it with a magnifier, there's loads of crud swirling around. And that crud sticks tenaciously to you negatives, ruining them. At least that's what happened to me the first time I did this. Ruined a roll of 35mm B/W film. After it's filtered, it seems to work fine. Maybe some brands of white vinegar out there are already filtered, but it would be best to check.

I wasn't gonna use it on film, just printing, but good to know! Would a coffee filter work? I didn't see much difference in the prints between diluted unfiltered vinegar and the kodak acetic acid solution (lol vinegar) stop I was using before... As far as negs are concerned I always just use lots of water which has not failed me yet. Thanks!

 

[angrykitty]

Both adm and MattIng are correct. Another way of saying it is that the ratio of water to vinegar should be 3 to 2; that is, use 3 parts of water for every 2 parts of vinegar.

Regards,

Dave

Yeeey! A simple answer! Someone once told me I should always use the K.i.s.s. (keep it simple, stupid!) method in the darkroom... Thank you!

 

[2F/2F]

OK I'll ask it.

Why would you want to do this. Stop bath is ridiculously cheap, available and easy.

Ditto. I have been using my current $7 bottle of Kodak Indicator Stop Bath for about four years now, and that is with a whole gallon of working solution having been poured out when it was still good by accident once.

Using vinegar is not only false economy, but it does not come with directions, or indicate when it has pooped out. IMHO, make your life easier and spend the sawbuck every few years on a bottle of the proper stuff. You can save much more money by mixing your own developers and fixers than you can by finding alternative sources for stop bath.

This being said, 400 mL of your vinegar to 600 mL of water will make a two percent working stop bath. Since you need to reduce the concentration from 5 percent to 2 percent, you are reducing it to 2/5 of the 5 percent concentration. So, all you have to do is multiply your final volume by 2/5 (meaning multiply by two and then divide by five) to find out the amount of the solution that should be your concentrated vinegar. One L times two is two L, divided by five is 400 mL of concentrate, and the rest of the liter (600 mL) is plain water.

 

[MattKing]

Dave Martiny is right - but only for 5% vinegar. If you have vinegar with any other concentration, you do have to use one of the slightly longer calculations.

That being said, almost all vinegar is 5%.

As for filtering, paper coffee filters would probably be fine.

 

[angrykitty]

Ditto. I have been using my current $7 bottle of Kodak Indicator Stop Bath for about four years now, and that is with a whole gallon of working solution having been poured out when it was still good by accident once.

Using vinegar is not only false economy, but it does not come with directions, or indicate when it has pooped out. IMHO, make your life easier and spend the sawbuck on a bottle of the proper stuff.

This being said, 400 mL of your vinegar to 600 mL of water will make a two percent working stop bath. All you have to do is multiply your final volume by 2/5 to find out the amount of the solution that should be your concentrated vinegar.

Well at the moment, for me, it's not more economical to pay more for a bus ride there then a gallon of the stuff. And it's also more economical for my laziness in avoiding the brutal bike ride.

But amongst my research I found a tip about the exhaustion tell, which is that the liquid will feel greasy between your fingers once it becomes alkali. If it's slimy it's dead - and a simple part to part dilution seems easy enough.

I don't see what all the fuss is about really. Shoot, you'd think we were talking about camera models with all this commotion (not gonna go there...)