XTOL Problem

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pufy

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Ok, after a couple of years of rodinal i decided to give xtol a try. Bought a 5 liter pack, mixed it, used it 5 times. It's been sitting in the dark for the past couple of weeks and when i took it out there was some gunge or something in it. Hope the picture will help. Is this normal, cause it sure doesn't look like that to me.
 

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Or you can filter it with a coffee filter, from one container to another. I was running a replenishing cycle on XTOL stock, but it eventually started acting up a little then died suddenly so I'm back to Rodinal. I do like Tri-X in XTOL stock though.
 
It may be harmless, see whether you can dissolve it by stirring. On the other hand, XTOL has quite a reputation for turning bad very suddenly - in your place I'd run a test strip through it before using it on anything relevant.

I only use it one-shot, and even then, it sometimes turns sour on me after a pretty arbitrary amount of time - usually it is fine for more than half a year, but when it goes, it goes quick, within a week or two. Many people have reported that it may die on you overnight if you store it half-used. It really is a developer you ought to test after longer breaks.

If you don't use it one-shot, you may have to reconsider your habits - you should really change to one-shot or use more film and develop it on a more regular, frequent schedule. Developers designed for lab tank/hanger use do not really stand up well to multiple runs on a amateur schedule - tank developers have to be worked and replenished several times a week, or they get out of control.
 
I experience some sediment now and then. Especially when it is a bit colder. I guess it some crystallization. When dissolved again it is harmless.
I noticed that when the stock turns yellowish it is time to get rid of ti.

Cheers,

Mihciel Fokkema
 
Seen it too.. I believe I have a thread here somewhere on "fuzzy" Xtol 🙂

It is, as everyone else has said, basically harmless. I've never had an issue with it harming negatives.

Cheers,
Dave
 
As Dave says, somewhere around here is a thread containing the chemical-ly details. As I recall, it's bits of harmless condensates.

A flap developed several years ago over Xtol allegedly going bad suddenly, but that's seems to be very old news at this point. Believe it had something to do with the one-liter package, which is the reason Kodak only sells it in the 5-lliter mix. Apparently chemicals can become obstreperous if they don't like their surroundings. 😉

I've stored Xtol in 500ml brown bottles in the fridge for more than a year and used it with no issues.
 
It usually is the result of the chelating agents removing divalent cations from the water you have used. Filter, trial, decide to toss or keep.

Marty
 
thanks a lot for the input guys. freakscene- didn't quite understand what you said there, but if it helps i should mention that i used demineralized water (the one you use for the car batteries and such).
 
I've used Xtol off and on for more than a decade and never had it go bad. For three years, I used it replenished and went through a 5ltr mix just as replenisher. It gets real grungy at the bottom of the tank when you do that, but it still develops just fine. BTW, I do store it in brown glass bottles, not clear plastic ones.
 
Even Kodak says, "Part A must be TOTALLY dissolved before adding Part B."
Well? Did you? Are you sure? It takes me several minutes of concentrated effort to get the last few grains of A dissolved. I've never had any trouble. Even after a year in the fridge too!
 
venchka said:
PS: I mix Xtol with distilled water and store in an air free enviornment.
Click to expand...

That's what I do, too. I store it in 500 ml bottles without any airspace (right up to the cap). I wrap the cap-bottle junction with paraffin film tape (Parafilm) too, to further limit gas exchange.

I've stored XTOL prepared this way for about a year, and once-opened bottles for about 3 weeks.

Zero problems.
 
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pufy said:
thanks a lot for the input guys. freakscene- didn't quite understand what you said there, but if it helps i should mention that i used demineralized water (the one you use for the car batteries and such).
Click to expand...

Freakscene just means that there are dissolved metal ions ("divalent cations" because they usually have a charge of +2) in water. Transition metals. Calcium, magnesium, etc. Tap water can contain a lot of divalent cations, and there's less-but-still-some in deionized/demineralized or distilled water.

XTOL goes off in the presence of certain metals, so it contains a chelator (probably EDTA) that binds the metals incredibly tightly* so as to inactivate them. The chelator-metal complexes might under certain conditions fall out of solution. That might be what you're seeing.

Even so, I think it's a really good idea to use demineralized water for concentrated stock solutions. I use tap water for diluting to working stock, though, and with the water in my area I don't seem to have any problems.

As Freakscene says: filter through a coffee filter, do a clip test, and you're good to go.

*In this context, "tightly bound" can mean molar dissociation constantse in the sub-nanomolar range, all the way down to 10^-22 M for some metals!
 
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semilog said:
Freakscene just means that there are dissolved metal ions ("divalent cations" because they usually have a charge of +2) in water. Transition metals. Calcium, magnesium, etc. Tap water can contain a lot of divalent cations, and there's less-but-still-some in deionized/demineralized or distilled water.
Click to expand...

Yes, exactly. And whether they precipitate out seems to depend on the ratios of the different types of cations present. Use MilliQ or heat distilled water to completely avoid this. Fe2+ is among the worst common elements for Xtol failure; it catalyses the oxidation of the ascorbate that Xtol relies on for its activity.

semilog said:
XTOL goes off in the presence of certain metals, so it contains a chelator (probably EDTA) that binds the metals incredibly tightly* so as to inactivate them. The chelator-metal complexes might under certain conditions fall out of solution. That might be what you're seeing.
Click to expand...

The chelators mentioned in US Patent #5,853,964 are Particularly useful sequestering agents include ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, 1,3-propylenediaminetetraacetic acid, 1,3-diamino-2-propanoltetraacetic acid, ethylenediaminodisuccinic acid and ethylenediaminomonosuccinic acid. The patent mentions that the sequestering agents can be present in an amount of from 0 to about 0.02 mol/l. This means we don't really know what chelators are in Xtol without looking closer ourselves.

An aside - the pH of Xtol and the formulae mentioned in the patent varies, so what is going on in the commercial version really is clearly different to the commercial version.

semilog said:
Even so, I think it's a really good idea to use demineralized water for concentrated stock solutions. I use tap water for diluting to working stock, though, and with the water in my area I don't seem to have any problems.
Click to expand...

Absolutely. I use MilliQ water even for D76 stock.

semilog said:
As Freakscene says: filter through a coffee filter, do a clip test, and you're good to go.
*In this context, "tightly bound" can mean molar dissociation constants in the sub-nanomolar range, all the way down to 10^-22 M for some metals!
Click to expand...

The chemistry of those bonds is very interesting, complicated and variable.

Just remember that a little care is needed and you'll be fine.

Marty
 
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