Kodak Indicator Stop Bath

littlepawli

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I am new to photography so I am a novice to understanding how to mix chemicals.

I have a question regarding your Kodak Professional Indicator Stop Bath Liquid net content 16 fl oz. I confused on the instructions for mixing this product.


Do I simply have to dilute this product by the following ratio?

1 Acetic Acid : 64 Water


If I wanted to make 2 gallons of this solution would I do the following?

4 ounces of Kodak Professional Indicator Stop Bat

256 ounces of Water


After the dilution stated above do I need to further dilute the Stop Bath to use in a tray or do I simply put 50 ounces of the solution I mixed above in the tray because it is already diluted for usage?
For example further dilute the solution as followed for tray usage:

1 ounces Diluted Stop Bath

64 ounces of Water
 

SCraig

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You only dilute it once. I don't remember the proportions, but if 1:64 is correct then your math is correct as well. Four ounces of stop bath plus 256 ounces of water, then pour what you need into the tray.
 

ann

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At our lab i just pour in enough to make the water take on an orange effect. with film just a few drops so that the solution looks like *pardon the reference) urine color when vit. c is being sluff off.

For over 65 years I have never measured or mixed a gallon at a time.

WIth Kodak has an indicator it will turn purple when it is no longer working, altho, I usually toss it long before that time when printing, and with film use it as a one shot solution. Just much easier in a gang darkroom
 

Derrel

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Whatever happened to vinegar????
 

Josh66

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Honestly, stop bath is probably cheaper anyway. A bottle is maybe $10 and should last well more than a year if reused. I mix a liter at a time, I typically get around 60 rolls out of a liter before it starts changing color.
 

Gavjenks

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Stop bath is almost never cheaper than grocery store vinegar, because stop bath usually IS vinegar, just more concentrated. Yes, you save on shipping less water, but you're also buying a much more "specialized" product, which costs more due to small volume. The latter tends to outweigh the former in affects on costs.

Kodak indicator stop bath, for example, is nothing more than water, acetic acid (vinegar), and a chemical that changes color when there's not as much acetic acid in the solution anymore. It costs $10 a liter, and is diluted to 1/64th.

White distilled vinegar from the grocery store is about $2 a gallon, or $0.50 a liter, and it should be diluted to 1/5th for use.



So it's 12x more concentrated (64/5) and 20x more expensive (10/0.5), making it about twice as expensive per roll of film developed than grocery store vinegar.

If getting a colored indicator is worth paying twice as much for your stop bath, then go for it. it's not exactly the most expensive part of the process either way. But if you want to keep costs down, and are willing to just mark off on a piece of paper how many times youve used the stuff, get the generic.
 

Josh66

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How many rolls is a bottle of grocery store vinegar good for?

By my math, I can stop approximately 1770 rolls from one $10 bottle of Kodak Indicator Stop Bath.
473mL bottle, 16mL of concentrate per liter = 29.5 liters of working solution. 60 rolls (at least) per liter of working solution. A gallon of distilled water is 80 cents here. 29.5L = 7.8 gallons X $0.80 = $6.24.

Total cost, just over $16 to stop 1770 rolls. I don't know about you, but 1770 rolls of film is what I would consider "a lot", lol. That's $0.009 per roll. You're saying THAT is 12 times more expensive than vinegar??
 

Gavjenks

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Again, kodak indicator stop bath is literally the exact same chemical as grocery store vinegar. They are both water (H2O) and acetic acid (C2H4O2) mixed together. One of them has an indicator chemical added, but this has nothing to do with how long it lasts.

So without even doing the experiment, I can assure you that if Kodak indicator stop bath is enough for 1770 rolls, then the equivalent (by total amount of acid molecules) amount of grocery store vinegar will also be enough for 1770 rolls. Acetic acid doesn't know whether it is Kodak brand or Hyvee brand acetic acid. A molecule is a molecule.

But those identical molecules cost you half as much from the grocery store shelf. They do not however come with a handy indicator, so you'd have to keep track with pencil and paper instead. If this inconvenience is worth paying the extra amount, then go for the Kodak. If not, go for the grocery store.




(If you insist on the math: The equivalent amount would be 1.5 gallons of off the shelf vinegar, which is 6 liters. You dilute grocery store to 1/5th concentration, so those 6 liters become 30 liters working strength, just like your kodak. But the 1.5 gallons of grocery store only cost about $3-4, not $10)
 

Josh66

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Your figures are not accurate, BTW. The stop bath is $10 for a 16oz bottle (473mL) - from that you can make 29.5L, not 1L.

If grocery store vinegar is $0.50/L and we use my figures for number of rolls and cost of water with your figure for dilution (1/5) - it works out to about $9 total cost (compared to $16 for the stop bath) to use grocery store vinegar to stop 1770 rolls of film.

So, I admit that it is cheaper ... but nowhere near 12x cheaper. ("Half" the cost would be close enough for me.)

Either way, the cost to use stop bath is ridiculously low. Less than a cent per roll. If I were looking to cut film processing costs, it would not be with the stop bath.



EDIT

The price of stop bath seems to have gone down considerably since I last bought a bottle. Freestyle has it for $6.29 for a 16oz bottle right now.

http://www.freestylephoto.biz/1464247-Kodak-Indicator-Stop-Bath-16-oz.


Updated figures for Kodak Indicator Stop Bath:

$6.29 for 473mL plus 6.24 for water = $12.53 total cost to stop 1770 rolls - only $3 more than vinegar. $0.007 per roll.
 
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Josh66

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The difference in cost is insignificant. Use what you want, but I'm going to keep using stop bath. Just like I will keep using Photo-Flo (or some other wetting agent) instead of dish soap.

These items are not the things you should be looking at if you want to save money. Buying bulk film is the first place I would start. I just loaded 19 36 exposure rolls of Ilford Pan F+ from a 100' bulk roll I bought for $63. 36 exposure rolls of Pan F+ cost $8 each. You do the math on that one to see how much I saved. :lol:
 

Gavjenks

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Huh?

30L working strength = 6L stock strength off the grocery store shelf (1/5 dilution). 6L * 0.50 = $3.

30L working strength of kodak apparently = $10 (doesn't matter what size bottle it comes in or whatever).

So it's 3x cheaper.

Anyway, the main advantage for me is not cost anyway. It's is being able to walk to the store and come back with more stop bath 10 minutes later. If I'm doing stand development, I could even go buy stop bath AFTER the film has already begun developing and make it back in time!

Why spend 10 minutes online shopping and entering credit card info, etc., and then wait a week for delivery, AND pay shipping to get a chemical that I can already pick up for less money on my way home from work instantly and with less effort (while supporting local businesses to boot)
 

Josh66

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OK - it costs roughly $12 to make 29.5L of Kodak Indicator stop bath. ($6.29 per bottle, plus $6.24 for water)

If vinegar is $0.50/L and we dilute it 1/5, it would cost $2.95 in vinegar to make 29.5L. 29.5/5=5.9L of vinegar required ... times $0.50/L = $2.95 total cost of the vinegar. Plus $6.24 for the water. Roughly $9.20 total cost to use vinegar compared to $12.50 for stop bath.

You didn't include the cost of water.

$3 cheaper to use vinegar. And we're dividing that cost over 1770 rolls of film.

I still say that the difference in cost is insignificant. We're talking something like $0.007 a roll compared to $0.005 a roll...


edit
Why spend 10 minutes online shopping and entering credit card info, etc., and then wait a week for delivery, AND pay shipping to get a chemical that I can already pick up for less money on my way home from work instantly and with less effort (while supporting local businesses to boot)


10 minutes of my time and a week for delivery is not a big deal for me when I'm buying something I'll still be using 2 years later. Not sure about you, but it takes me a long time to shoot that many rolls of film. :lol:
 
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Gavjenks

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Plus $6.24 for the water.
:scratch:
Why do you need distilled water for stop bath? It's not drying on the film or anything. There's way more crap floating around in once-used developer or once-used fixer, for instance, than in tap water. 24 L of tap = 1 penny


10 minutes of my time and a week for delivery is not a big deal for me when I'm buying something I'll still be using 2 years later. Not sure about you, but it takes me a long time to shoot that many rolls of film. :lol:
In actuality, I find it annoying to funnel my stop bath back into the container, and usually only use it once or maybe twice, so the cost matter more too for that reason.
 

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