Keeping fixer fresh

[tkamiya]

We talk about developer storage practices all the time but I've never seen the same discussion about fixers.

My question is very simple. For both Kodak's regular fixer and Ilford's rapid fixer, ONCE MIXED and made into WORKING STRENGTH SOLUTIONS, is it damaging to the solution if I keep it in 1/2 full bottle with air? Does it degrade in presense of oxygen?

Thank you!

 

[brucemuir]

Eventually you will see sulphur precipitate even with concentrated stock solution.
I used to get the leave behinds from students at the local community college so I sometimes would end up with all kinds of stuff.

I would always grab the partly used bottles of Kodafix concentrate and it would sometime show precipitate after about 3 years.

I've never had an issue with working strength solutions but I always use it before it sits for too terribly long. Say like 6-9 months.

This probably doesn't help much but...

 

[tkamiya]

I usually keep fixer for about 6 month or until exhaustion which tends to happen at about the same time. A motivation for this question is two fold. While I can always test fixer strength, the bag which fixer comes says the usual "2 months in stoppered bottle". But I know it lasts longer than that from my own experience. So I wanted to understand the mechanism (other than exhaustion) in which fixers degrade. Also, because of the size of bottles I have, my next batch ends up being about half full. Is this sufficient or should I better buy a smaller bottle?

 

[Photo Engineer]

My experience with TF-4 and TF-5 indicate long shelf life even as working strength solutions.

PE

 

[tkamiya]

Thank you PE, but few questions....

What's TF-4 and TF-5 in laymen's term? What's the mechanism behind fixer's death other than exhaustion?

 

[Photo Engineer]

Well, pH is one of the most important properties influencing fixer stability and oxygen is another. Both TF fixers are outside of the pH range where most damage by pH is done. Therefore they have longer shelf and mixed life than acid fixers. Sulfite with oxygen forms sulfate. While sulfite is present it prevents oxidation.

So, with oxygen and low pH, they hypo in fixer decomposes into H2S (Hydrogen Sulfide) and Sulfur. The fixer smells like rotten eggs and gets cloudy. The cloudy particles in the fixer can cause spots in film if used to fix film. The particles become trapped in the gelatin matrix.

PE

 

[tkamiya]

Ron,

What's TF-4 and TF-5? Are these model number for Kodak fixers? Are you referring to Rapid fixers??

 

[michaelbsc]

Can you filter the particulate and still use the diver, albeit with reduced capacity? Or is it shot?

Can heat and stirring reverse the decomposition so it becomes new again?

 

[Photo Engineer]

TF-4 and TF-5 are long life, high capacity fixers from the Formulary. There are a few long threads on this here so I assumed too much. Sorry. They take advantage of the properties that I gave in my previous post.

Once the particles form, they are very difficult to filter out due to size. These are Sulfur particles. The reaction cannot be reversed by any means whatsoever. If you were to filter it, the capacity and rate would be changed and so the clearing time would have to be re-determined.

PE

 

[Theo43]

Have you considered buying a bag of glass marbles at a craft store, and adding them to the partial bottle until it is again full to the top? I have not tried this myself as I am not set up yet, but it sounds reasonable.

 

[RalphLambrecht]

Have you considered buying a bag of glass marbles at a craft store, and adding them to the partial bottle until it is again full to the top? I have not tried this myself as I am not set up yet, but it sounds reasonable.

I was taught this trick about 50 years ago by my Dad. It works well against oxidation but I don't enjoy the cleaning part too much. Another way was posted here on APUG and involves spreading the volume over five containers. here is an example how 5 liters are stored:

1x 2 liters
2x 1 liter
2x 1/2 liter

Then start with the smallest containers and when empty refill them from the larger container. This way, you are always dealing with almost filled containers, but you end up having a lot of them!

 

[tkamiya]

spreading the volume over five containers.

That's the method I came up originally for keeping XTOL fresh. It's based on binary. In actual use over one year period, I had an issue with the smallest bottles. Since they have to be squeezed to rid of air when it's half full, repeated stress caused the bottles to crack/tear.

Since then I modified my method to use four 250cc instead of two 500cc. This way, there is no squeezing involved.

Of course, I now use D76 exclusively.... so it's little different.

 

[Photo Engineer]

Alkaline and neutral pH fixers can last for years with no decomposition of either the concentrate or the working solution.

PE

 

[brucemuir]

Alkaline and neutral pH fixers can last for years with no decomposition of either the concentrate or the working solution.

PE

I had some TF-4 that I got back in 2004 (somewhere around there) and I used it at the beginning of 2010 and it was fine.

 

[MarkL]

Too bad the TF-4 instructions say, I believe, that it's best to use within one year.

 

[RalphLambrecht]

I had some TF-4 that I got back in 2004 (somewhere around there) and I used it at the beginning of 2010 and it was fine.

The oldest fixer I've ever used was an internet purchase of Ilford Hypam. It turned cloudy after it was six years old. I discarded it at that point.

 

[tkamiya]

Speaking more generically, rather than brand names, when it comes to keeping properties, Rapid fixer that are usually alkaline is better than regular fixers??? If Acid fixer (regular fixer) decades when acidity decreases, I'm guessing alkaline fixer decades when alkalinity decreases. Would that mean stop-bath is harmful to rapid fixers?

 

[Photo Engineer]

Stop baths can be harmful to all fixers if the stop is acid enough and buffered enough. A plain 1% - 2% acetic acid stop will generally not harm a fixer under normal use. It is good to check the fix time and wash times though to make sure that the fixer is not saturated with silver and is not losing strength.

PE

 

[RalphLambrecht]

Speaking more generically, rather than brand names, when it comes to keeping properties, Rapid fixer that are usually alkaline is better than regular fixers??? If Acid fixer (regular fixer) decades when acidity decreases, I'm guessing alkaline fixer decades when alkalinity decreases. Would that mean stop-bath is harmful to rapid fixers?

This reads as if the difference between rapid and regulars fixers is in their pH, but it actually is in their main ingredient. Regular fixers are contain sodium thiosulfate whereas rapid fixers contain ammonium thiosulfate. Rapid fixers can be acid or alkaline based. Ilford's Hypam for example is an acid-based rapid fixer.

 

[Photo Engineer]

Good point Ralph!

Alkaline and acid fixers can be rapid fixers, but alkaline fixers keep longer and wash out more rapidly. Neutral fixers can be rapid fixers and they keep longer and wash out more rapidly than acid fixers, and are slightly slower in wash rate compared to alkaline fixers. Both neutral and alkaline fixers have long shelf lives, but acid fixers are quite limited in shelf life.

Rapid fixers use Ammonium Hypo and regular fixers use Sodium Hypo.

PE

 

[tkamiya]

Thank you, gentlemen!