Acid impact, home brew citric acid stop bath

redbandit · Mar 26, 2023

What is the implication issue with chemical carryover from developer chemical when using home made citric acid stop bath?

What is the carry over issues with home made citric acid stop bath once you drain it out, and put the fixer in?

I just had to ask as the wording on the eco pro chemicals implies "major" impact can occur with other types of chemicals

MattKing · Mar 26, 2023

Both acetic acid based stop bath and citric acid based stop bath help stop developer activity, and eliminate the negative effects of developer carry-over into fixer.
Citric acid tends to be more expensive when incorporated into commercially produced indicator stop bath. It may be easier to make an acetic acid based indicator stop bath in a very high concentration. And at working strength, acetic acid based stop baths impede the growth of mould and other undesirables, while citric acid based stop baths promote those growths. As a result, whether or not you can store and reuse working strength stop bath depends on the acid it is based on: acetic acid yes, citric acid not a good idea.
In either case, dilution to the right amount of acidity is important.

mshchem · Mar 26, 2023

I use Ilford citric acid stop for printing, open trays with acetic acid can be pretty stinky. People have given me stop and other chemicals over the years. I don't keep working baths for long. I can't recall, recently, having the indicator change to purple as I toss it before it's exhausted.

redbandit · Mar 26, 2023

I havent been able to do much printing in the past 2 months. Made first two test prints in maybe 6 weeks...

The developer smelled like rotting urine, so it got tossed. making a new batch in morning. Plan on trying to do 1 print a night. multi tone 5x7 here we come..

just made fresh stop and fix 2 weeks ago, And am thinking about the long term...

NO idea how long home brew citric acid stop would last. And over all cost... Not sure how long my eco pro lasts.

Donald Qualls · Mar 26, 2023

I've used acetic acid stop bath exclusively for the past half century. Sure, it makes some smell in the darkroom, especially in trays, but when people ask why I don't shoot digital, I tell them it's not photography for me unless I can smell the chemicals. Further, acid fixers usually smell a lot like acetic acid stop bath (sometimes with a trace of sulfur dioxide), so a second tray of acetic acid is no big deal.

Also, I quite like having a jug of stop bath under the darkroom counter alongside the developers and fixer, so I just have to pour it into the graduate as part of setting up to develop. Having to mix from powder each time would be annoying, especially since I'm often trying to go from film in the tank (sometimes for a day or more) to hanging in under an hour.

pentaxuser · Mar 26, 2023

redbandit said:
What is the carry over issues with home made citric acid stop bath once you drain it out, and put the fixer in?

I just had to ask as the wording on the eco pro chemicals implies "major" impact can occur with other types of chemicals

Isn't the last sentence the key to what is being asked? I can understand why it is being asked given what has been found in eco pro literature but what I don't understand is why does eco pro say major impact when an acid stop bath is there to prevent any impact a carryover of developer might have in the life of the fixer and secondly the stop bath prevents any carryover of development as it stops this instantly which is why it's called "stop" bath

I am puzzled like redbandit. If the impact mentioned is in the context of film or print processing I'd say ignore it as it doesn't make any sense to me nor it would seem does it make any sense to the other respondents

redbandit, can you link us to the eco-pro literature or quote its context?

Thanks

pentaxuser

Sirius Glass · Mar 26, 2023

Any stop bath is beneficial to non pyro developers and much better than just using water.

MattKing · Mar 26, 2023

redbandit said:
NO idea how long home brew citric acid stop would last. And over all cost... Not sure how long my eco pro lasts.

Not very long at all - mould growth is the problem.
But one shot is easy - its just I can't put my hands on the recipe right now. Is it 1 tablespoon citric acid per litre?

Rick A · Mar 26, 2023

redbandit said:
I havent been able to do much printing in the past 2 months. Made first two test prints in maybe 6 weeks...

The developer smelled like rotting urine, so it got tossed. making a new batch in morning. Plan on trying to do 1 print a night. multi tone 5x7 here we come..

just made fresh stop and fix 2 weeks ago, And am thinking about the long term...

NO idea how long home brew citric acid stop would last. And over all cost... Not sure how long my eco pro lasts.

I've had a bottle of EcoPro open and using it for about three years now, still like new(I don't print many silver gel prints). I keep a liter of working strength on the shelf with paper developer (LPD) and working strength EcoPro Neutral fix. I sometimes go weeks without printing and no issues. I bought some powdered citric acid for alt printing, I ad it to my first wash for VDB and salted paper prints. I mixed a liter of1% solution about a month ago and no mold growth.

redbandit · Mar 26, 2023

MattKing said:
Not very long at all - mould growth is the problem.
But one shot is easy - its just I can't put my hands on the recipe right now. Is it 1 tablespoon citric acid per litre?

its 1 or 2 tables spoons or teaspoons per liter.

Ive been curious as most of the literature for MOST of the commercial Stop bath products act as if you mix it up monday morning, develop prints or film till it is exhausted monday evening, then toss.

MattKing · Mar 26, 2023

redbandit said:
its 1 or 2 tables spoons or teaspoons per liter.

Ive been curious as most of the literature for MOST of the commercial Stop bath products act as if you mix it up monday morning, develop prints or film till it is exhausted monday evening, then toss.

If it exhausts, that means it is used up.
It isn't a problem with exhaustion, it is a problem with contamination.
Dilute citric acid is apparently a wonderful environment for growing mould.
Dilute acetic acid? Not so much. If only it didn't smell so much .

Maris · Mar 26, 2023

I use a Dektol - Citric stop bath - Rapid fixer sequence for gelatin-silver photographic paper and I've never had a chemical carry-over or cross contamination problem.
The rule that I follow is to let the print drain (on the diagonal) before it goes into the next tray. The drain time I was taught at photo-school is the length of the paper diagonal in inches converted to seconds.
For example a 8x10 print drains pretty completely in 12 seconds - and so on.

pentaxuser · Mar 27, 2023

redbandit said:
Ive been curious as most of the literature for MOST of the commercial Stop bath products act as if you mix it up monday morning, develop prints or film till it is exhausted monday evening, then toss.

Can you quote these examples that indicate it is exhausted within 12 hours. The Ilford literature says 7 days and that is for working strength solution

pentaxuser

bluechromis · Mar 27, 2023

I don't know what recipe of stop bath you are using. Anchell and Troop in "The Film Developing Cookbook" 2nd ed. say that if stop baths are not adequately buffered they quickly gain in pH and no longer arrest development. It is not enough that the bath has enough acidity to begin with, they must be formulated to maintain a stable pH.

Acid impact, home brew citric acid stop bath

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Acid impact, home brew citric acid stop bath

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