Citric Acid dor Stop Bath

I'm switching from Kodak stop bath to citric acid (powder form) to eliminate the smell. The only formulation I've found says to mix 15 grams per litre, but that's for paper development. Can I assume that it's the same for film development?

I meant "for" stop bath, not "dor. More coffee needed for these 6AM posts.

I would have thought that 15g is OK for film as well but a smaller amount may arrest development also. If we are talking B&W film then you might want to consider a water stop bath instead. Provided you use several fills and dumps then water does a good job. I switched from stop to water a few years ago and haven't seen any problems from the switch.

Given that the developer has already been dumped I don't think that what little remains in even the first 250 -300mls of water fill makes any real difference to how much longer the extremely diluted developer can act for those few seconds that the water is being swilled around and by the second fill the percentage of developer left must be so small as to be insignificant

pentaxuser

Thanks. I'll try it at that dilution. I hear others talk about not using stop bath, but I have a successful system in place, finally, and don't wish to introduce any variables into it. My thinking is that the film or paper will keep developing unless there's something to stop it, but that may not be the case. Seems like it would though.

If you don't mix your own and want to buy one, Sprint makes an indicator stop bath that has an added vanilla scent. It's not bad, imo, and I like that it's an indicator one. I don't know how far ranging it's available, though. It's made in Rhode Island, so I could always find it in New England, but can't always get it out here in the midwest.

momus said:

Thanks. I'll try it at that dilution. I hear others talk about not using stop bath, but I have a successful system in place, finally, and don't wish to introduce any variables into it. My thinking is that the film or paper will keep developing unless there's something to stop it, but that may not be the case. Seems like it would though.

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The term stop is a misnomer, it stops carry over of developer into fix, with some developers you could get stains on prints without donno about film developers...

Some people will be using a water bath without agitation to allow the development to continue differentially in shadows some even use a post bath of alkali for same reason.

But I understand a system. I use bulk film and some is not prehardened and using a acidic stop risks emulsion damage if I loaded the wrong film into a multi tank... So I never use acid.

Michael R 1974 said:

You can buy Ilford's Ilfostop. It's a citric acid low odor stop bath.

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I have just had a sniff at my Ilfostop and it has practically no smell except perhaps for a slight whiff of vanilla similar to that already mentioned.

The dilution mentioned does not vary between paper and film which adds, I believe, credence to the idea that 15g of citric acid per litre of stop applies to both paper and film.

Given the cost of Ilfostop and the fact that Ilford's estimated coverage is 15 x 135 films per litre then it isn't an expensive item.

Just be aware, momus, that there are threads/posts that claim that some film makes are susceptible to pinholes caused by acid stop. As far as I recall Ilford, Fuji and Kodak films were not amongst those claimed to be susceptible to pinholes allegedly caused by acid stop.

You might want to do a search, momus, and reach your own conclusions

pentaxuser

I use ca 15g citric acid/l as stop for both film and paper.

momus said:

I'm switching from Kodak stop bath to citric acid (powder form) to eliminate the smell. The only formulation I've found says to mix 15 grams per litre, but that's for paper development. Can I assume that it's the same for film development?

I meant "for" stop bath, not "dor. More coffee needed for these 6AM posts.

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You'll find that a 2%citric-acid stop bath for film is plenty strong.

pentaxuser said:

I have just had a sniff at my Ilfostop and it has practically no smell except perhaps for a slight whiff of vanilla similar to that already mentioned.

The dilution mentioned does not vary between paper and film which adds, I believe, credence to the idea that 15g of citric acid per litre of stop applies to both paper and film.

Given the cost of Ilfostop and the fact that Ilford's estimated coverage is 15 x 135 films per litre then it isn't an expensive item.

Just be aware, momus, that there are threads/posts that claim that some film makes are susceptible to pinholes caused by acid stop. As far as I recall Ilford, Fuji and Kodak films were not amongst those claimed to be susceptible to pinholes allegedly caused by acid stop.

You might want to do a search, momus, and reach your own conclusions

pentaxuser

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Pinholes caused by developer reacting with stop are rare, even with softer-emulsion films. Usually the developer has to be really alkaline for there to be any significant reaction. That said, this does happen from time to time. If in doubt, do a quick test (with the room lights on). Just soak a clip of film in your developer for at least three minutes or until it is rather black, then transfer it to the stop for 30 seconds. Rinse and examine it with a loupe for pinholes. Since the film should have developed mostly, any pinholes should be easy to spot.

Citric acid stop baths do not like to be stored for long periods. Citric acid is organic and grows mold/bacterial slime. I use mine at about half-strength and one-session. Acetic acid stops have the advantage that they can be stored for a long time and not exhibit any degradation.

Best,

Doremus

Xmas said:

The term stop is a misnomer, it stops carry over of developer into fix,

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Surely far from a misnomer?

Almost without exception, film and paper developers require an alkali solution to work. Placing the film or paper in an acid solution is intended to quite literally "stop development" isn't it?
(Hence the importance of a stop bath, for instance, when doing lith development a la Rudman)

I stopped using the commercial Ilfostop. It lasts a long time, but it is 'pricey' given its ingredients. You can get 5lb of citric acid from brewing shops for well under $20, which would have the capacity of around 2,000 rolls of film, and in my experience, probably closer to 5,000 sheets of paper.

For simplicity, I just use a small pinch of it per liter, and use it one shot for film. Still working through a bottle of Ilfostop for printing.

As outlined in other threads, if you're at all experienced, indicator is not necessary, as it is difficult to see the initial shift to amber.

I think PE recommends the highly scientific 'squeak test', which doesn't need an indicator.

EDIT: I just noticed you were asking about film. Please don't try to squeak test your film...

For that, citric acid is cheap enough, easy enough to use, and very mild at the dilution necessary for film, so, as above, I just use a pinch and use it one shot. Nothing to worry about going down the drain, and it saves water.

I was wondering about the shelf life. Fleabay has a lot of cheap citric acids in powder form, so maybe it would be best to mix it up in small batches as needed (or one shot) and not store it more than a few weeks. The vanilla scent has me interested. I wonder if I couldn't put just a few drops of juice from a lemon (citrus fruit, right?) into my gradient at developing time and have a nice smelling stop bath? I'm probably stuck w/ the fixer smell, and fortunately I actually like the smell of most developers I've tried.

Thanks for the PDF link Ralph! Neat stuff in there.

momus said:

I was wondering about the shelf life. Fleabay has a lot of cheap citric acids in powder form, so maybe it would be best to mix it up in small batches as needed and not store it more than a few weeks. The vanilla scent has me interested. I wonder if I couldn't put just a few drops of juice from a lemon (citrus fruit, right?) into my gradient at developing time and have a nice smelling stop bath?

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RE: lemon juice,

I'd be concerned about the sugars in it, too. Think of how sticky dried lemon juice is, and how the pulp can adhere to it...

As far as the shelf life, some friends of mine that do what I'd consider large scale home brewing (they do a couple kegs at a time), one of which is also a chemical engineer, seems to think that when kept cool and dry, citric acid should have a shelf life measured in years. I use Nalgene lab grade jars (I use these backpacking camping a lot, too... they're safe for most chemicals, durable, cheap, and airtight), and keep the full ones in a dry dark place, filled to the brim with a couple packets of silica gel to keep moisture out. Despite all the warnings, I've well mixed and divided powdered concentrates this way (usually in half or quarters). I have a quarter bag of D76 in one of these jars, which is also kept in a sealed ziploc bag that I forgot about, and was going on 2 years without oxidation, and activity was spot on with scrap film. If something that oxidizes much quicker kept that long, I wouldn't have concerns about using properly kept citric acid that was years old. Plus, there's little harm done if it does go bad, negatives and prints will come out fine. If it dies, it's cheap-- just toss and replace.

OK, no lemon juice. I'll have to reserve it for the mixed drinks and tacos. That is amazing longevity for D76. Mine gets "funny" after no more than 3 weeks after it's mixed. Going to TD-16 seems to have fixed that though. The batch I mixed up over 2 months ago is still looking good. I can usually tell when my D76 starts going off (I think it is actually becoming more active) by my skies in a shot. W/ the TD-16, the skies still have nice, tight grain (Tri-X is my only film that I shoot anymore). It gives a very similar negative compared to D76. Very close, and prints made from TD-16 and D76 are indistinguishable from each other, at least at my place.

momus said:

OK, no lemon juice. I'll have to reserve it for the mixed drinks and tacos. That is amazing longevity for D76. Mine gets "funny" after no more than 3 weeks after it's mixed. Going to TD-16 seems to have fixed that though. The batch I mixed up over 2 months ago is still looking good. I can usually tell when my D76 starts going off (I think it is actually becoming more active) by my skies in a shot. W/ the TD-16, the skies still have nice, tight grain (Tri-X is my only film that I shoot anymore). It gives a very similar negative compared to D76. Very close, and prints made from TD-16 and D76 are indistinguishable from each other.

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I'll check out TD-16. My experience with D76 was it lasted MUCH longer in powder than in stock solution, and was frustrated by bottles dying after a few weeks. I did an initial test with a few rolls of film a couple years ago, where I measured out the powder using an accurate scale, enough to make 8 oz of stock solution. I did a few, and kept them in seperate baggies in a large Ziploc bag. No discernable difference from the different ratios that could happen by doing partial quanitites Towards the end of the bag is still worked like the first couple rolls, too!). I ran with it after that, so I just divide up bags of D-76 into 1 quart little jars, and mix them up a liter the night before I develop. After I think about 30 rolls and a bunch of sheets of 4x5 doing this, I don't see any variation. But that's a separate issue that could cause debate, so I'll leave that there.

As far as citric acid, it's very commonly used as a food preservative. Kept properly, it's hard to imagine that it will go bad before you could use it up, even in lrge quantities, and when it starts to go bad, it loses potency, so you can either toss it or mix more in. It doesn't need to be super precise, as long as the pH isn't too high or low.