Stop Baths

Almost all the years I have used the normal Acetic Acid stop bath for both Black and white (45) or colour printing. (24) One time I changed over to citric acid based stop bath and as usual used it as and when I did printing using my Nova Deep tanks. The one occasion I used the citric acid but didn't do any printing for about 2 weeks when I went to use it, the top of the stop bath slot was filled with mold. I have never had this with acetic acid bases SB.

Has anyone else come across this before? The reason I am asking due to the acetic acid base causing me skin problems and want to change over to the citric based which I feel will be gentler and not cause me the problems I am having.

Using plain water is not an option!

This has been observed and mentioned in a number of other threads as well. As I think you have already concluded, you are stuck with dumping citric acid stop more frequently due to the mould- forming characteristic if acetic is causing you a problem.

If you have long periods between printing then the cheapest method might be to buy it as a powder( Silverprint sell it or get it in large quantities from home-brew suppliers) and make up a litre each time and then dump. 15g per litre is the figure I have seen mentioned but you might get away with less if it's a use and dump frequently routine

It certainly doesn't smell as vinegary as acetic acid stop so the darkroom smells less like a fish and chip shop.

pentaxuser

I always pour it back into a bottle, squeeze the air out just as if it were developer and cap. I never grow mold in working strength stuff but I did find it floating in years old bottles of concentrate I had when I got back into the darkroom. Had to dump that.

You know, I think that the best thing to do for stop bath is to use the acetic acid but...at a higher dilution and with more frequent change (ie, 'one shot'). You eliminate the strong smell, you work with 'always fresh' solutions, you don't use any more of the concentrate (glacial).

After film development flood the film with acetic acid stop bath at a 1%, or even 0.5%, strength. Your development WILL be stopped, immediately. For color film I use a couple (at least) of iterations so that the color developer is REALLY off the film (as I don't want ANY bleach to mix with developer residue). - David Lyga

Acetic acid acts as a preservative which is the reason why we pickle various foods. Bacteria and molds do not like it. But they view citric acid much as we do orange juice it is a food to them. You can slow down the mold growth by adding a small amount of classic Listerine to the bath. The thymol in the Listerine acts as a preservative. Try 30 ml per liter of bath to start. it will have no effect on film or prints.

I simply use citric acid in powder form (2 tablespoons on 1 litre of water) from the drug store next door and dispose of it after the session. Nothing simpler, nothing cheaper.

Citric acid stop is not recommended for colour printing.

White vinegar 1+9 w/ water for 1 minute. Works for B&W, have no knowledge for colour. Really, anything mildly acidic will work, but if colour does not call for acid stop bath then you'll have to use something else. It smells, but so does the Kodak stop bath that I have. People say that stop bath is actually cheaper than vinegar, but not at the Dollar Store it isn't :] You have to figure in shipping too w/ stop bath prices.

thefizz said:

Citric acid stop is not recommended for colour printing.

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I thought we were talking about B&W, at least this is the board for B&W.

Thomas.Goehler said:

I thought we were talking about B&W, at least this is the board for B&W.

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mbikerider said he was using it for both B&W and colour.

I've used citric acid stop at double B&W strength with RA4 with no apparent issues and far less odor. What problem is it supposed to cause?


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David Lyga said:

You know, I think that the best thing to do for stop bath is to use the acetic acid but...at a higher dilution and with more frequent change (ie, 'one shot'). You eliminate the strong smell, you work with 'always fresh' solutions, you don't use any more of the concentrate (glacial).

After film development flood the film with acetic acid stop bath at a 1%, or even 0.5%, strength. Your development WILL be stopped, immediately. For color film I use a couple (at least) of iterations so that the color developer is REALLY off the film (as I don't want ANY bleach to mix with developer residue). - David Lyga

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+1

Most of the stop baths available in Europe are of the odourless type, meaning they are citric acid based. I prefer acetic. It surely stinks but I don't mind the smell.

Roger Cole said:

I've used citric acid stop at double B&W strength with RA4 with no apparent issues and far less odor. What problem is it supposed to cause?


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As far as I can remember it was Photo Engineer who said citric acid stop was not good for RA4 printing.

thefizz said:

As far as I can remember it was Photo Engineer who said citric acid stop was not good for RA4 printing.

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Quite correct and being PE I have no doubt he also provided some form of explanation as well but I cannot recall now. It may be that double strength citric overcomes the issue cited by PE. If Roger Cole's experience is that it was OK then this is a good endorsement.

Clearly if the OP has a skin issue with acetic then any solution involving citric is by far the best bet.

pentaxuser

It's been years, back in the 90s. I was printing with the Tetenal RA4AT kit and getting the yellow whites that others have reported - there are posts on here about it but that was apparently due to the mono bath packaging of the blix, nothing to do with the stop. At any rate the change from acetic to citric made no difference in that respect. The double strength was per the Tetenal instructions for regular stop and I just continued that with the change to citric. SOMETHING in that chemistry flow made fumes that were about to choke me out, even with ventilation. The change from acetic to citric helped - I figured part of the problem was the fumes from the double strength acetic acid. The change from open trays to a Nova 8x10 PrintPod fixed most of the rest of the fume problem and I could print without choking. I never solved the yellow whites (including borders) problem though.

I'm planning to take up RA4 again when I get my new darkroom plumbed (and ventilated!) I'm willing to go back to acetic if there's a good reason but otherwise would keep using the citric that I use for B&W.


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EDIT: I did some searching and found the thread where I discussed the RA4AT problem. In that thread I say I don't recall if the yellow borders happened with the acetic but I'm now virtually sure they did, and another poster had the same problem. I know that ALL my RA4 prints from that era show yellow borders, and I know I made a lot of them with acetic before I changed to citric. I'll use whichever I need with future RA4 provided I don't choke on it:

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

My posts start at post #34 in that thread.

I save the acetic acid for French fries and chickpeas... cept when wet printing.