Storage of HCA - how and how long?

[tkamiya]

I use Kodak Hypo Clearing Agent. On packaging, it says storage life is 3 months in tightly stoppered bottle. Currently, I store mixed stock solution in usual brown plastic jug with no care to evacuate air.

Does HCA stock solution require the same level of care in storing developers? Does it oxidize in presence of air if the bottle isn't full? Since the packaging also says it will last for 24 hours in a tray, I'm thinking it does degrade fairly fast.

Why I ask? Kodak's fixer says 2 month storage in stoppered bottle but I routinely use it until exhaustion (by number of rolls or papers) and usually longer than 6 months. While it does take a little longer to clear, it does work and doesn't suffer sudden death like developers can. Informed sources tells me Kodak's ratings are very conservative and that is the reason for short life span spec on fixers. Seems in practical sense, I can't always go by packaging specs unless I want to be very conservative.

Looking forward to hearing practical experiences from experts here on APUG.

 

[R gould]

I have stored stock HCA for several months in bottles with no ill effects, I believe Kodak is very consertive in its estamites, maybe it wants to sell you more than you need,Richard

 

[tkamiya]

Well.... one thing is for sure.... using old HCA doesn't damage anything by itself. I still won't know if it is doing what it should be doing though. If it did nothing and with shortened wash time, enough fixer may remained in film and cause problem years down the road.

Hum....

 

[hpulley]

Test for residual after the washing is the only way to know I guess but I wonder the same about my bottle of Heico PermaWash. Once it gets down to a point where I can put it into smaller bottles but for now I wonder how it is doing. In working solution it doesn't seem to last very long, just one printing session.

 

[holmburgers]

Off topic slightly, but I've considered 2 months for an open bottle of Kodak fixer and 4 months for a stoppered bottle, doubling Kodak's recommendations. Do you think this is a safe thing to do? Longer? Yes, I could test it, but I'm just asking...

 

[hpulley]

For fixer the answer is to test it since you can. I suppose for HCA that is the answer as well, test for residual silver after you fix and wash.

At the moment it seems I can use a bottle of fixer up in 2 months so the point is moot for me but I wouldn't throw out chemicals without testing them. Developer at the bottom of a 500mL bottle gets brown and suspect but it can still be clip or paper tested. Test, test, test...

 

[tkamiya]

Why would you keep the bottle open? I've used fixer way over 6 months in almost full bottle with cap on with acceptable results. (takes little longer to clear) At 8 months I exhausted the capacity so no farther testing was done.

 

[holmburgers]

by "open" i mean not full to the brim, opened, not sealed w/o air since mixing.

 

[msa]

Try some T-Max.

Lately, I've been timing how long it takes to clear 70-80% of the pink tint in HCA. (The rest just has to wash out.) When it starts taking 'too long,' I re-mix.

One thing about HCA though, you can reduce the volume a fair bit without having it come out of solution. It's possible to store it concentrated, shake up, and dilute to working strength as needed.

 

[Vlad Soare]

Sodium sulfite solutions are basic (I believe they're pH 8.5 or thereabouts). As the sulfite oxidizes, it turns into sulfate, which is neutral. So I guess one could simply measure the pH of the solution. If it's close to 7, then it's time to mix a new batch. Precision is not really paramount; a cheap pH paper strip should do.
I haven't tried this myself, as I use to mix just enough for the current session and to use it one-shot. But I do have an old sodium sulfite solution (the B part of ABC Pyro), which isn't used up yet and I think by now is old enough to be useless. I'm going to measure its pH to see if I'm right.

 

[hpulley]

Heico Permawash is Ammonium sulfite and bisulfite though isn't it? Longer or shorter storage I wonder?

 

[Gerald C Koch]

The working ingredient in HCA is sodium sulfite. It will slowly oxidize to sodium sulfate which is less effectivre in removing hypo. HCA is buffered to a neutral pH so measuring pH to determine whether it has gone bad will not work. The main problem with HCA solutions is that they grow mold after being used. Emulsion is made from gelatin and provides a source of nutrients for various micro-organisms.

I would not exceed Kodak's recommendations and would check it for mold grpwth before each use.