Xtol Oxidation

While Xtol keeps for a long time in full bottles, it oxidizes in part full bottles. When a bottle is only 10% full the ratio of the volume of air to the volume of developer is over 80 times that when the bottle is 90% full, so the oxidation can go ever faster as the level in the bottle falls.
I ran some tests on ingredients of Xtol. 2 lots of 12g/L sodium ascorbate without and with addition of 20 g/L sodium sulfite were exposed to the air and the color change noted (see attachments).
After 37 days the ascorbate alone had oxidized to an orange color, possibly dehydroascorbate as dehydroascorbic acid is reported to be orange. The ascorbate plus sulfite solution showed much less color change.At 130 days the colors had darkened.I cold not get rid of the orange color by adding sodium sulphite.
I am inclined to favour this explanation for these color changes:
In presence of sodium sulfite the ascorbate does not oxidize to the orange compound, probably dehydroascorbate, but to a relatively colorless substance which may be an ascorbate-sulfite compound.
So it is the sodium sulfite which in some cases leads to the oxidative failure of Xtol with minimal color change.
Thanks for comment.

Michael,
Ascorbate=L-ascorbate is a mirror image of isoascorbate=D-araboascorbate=erythorbate.
AFAIK the photographic properties of the two are the same as they do not have any reactions in this case where the mirror image type has any effect.

Couple weeks ago I used Xtol that I had mixed november 9 2007 and bottled into large 40oz beer bottles
kept in basement on the concrete at about 43-50 degrees

Well, the bottle I used was half full and has been used on/off since being mixed


Worked fine. Negs were done at 9 minutes. I just guessed 9. assorted 35mm film had been shot years earlier so "overdeveloped" it
3 rolls large paterson tank
1:1

Mix it with distilled water
dont whip in air while mixing maybe
I use wooden forks
keep moderately cold
seal with saran wrap and screw caps

I've never had failure.

Sodium iso-ascorbate which is often called sodium erythorbate is slightly more active as a developing agent.

sun of sand, the difference in stability can be easily explained by the difference in tap water across the globe. People from Australia report, that their Xtol goes bad within days, while yours evidently lasts forever. The key issue seems to be Iron content of tap water. While Xtol uses a powerful sequestering agent (DTPA) to control the Fenton reaction, more Iron still means more remaining effect and less stability.

I aways mix my XTOL in steam distilled water.

Rudeofus said:

sun of sand, the difference in stability can be easily explained by the difference in tap water across the globe. People from Australia report, that their Xtol goes bad within days, while yours evidently lasts forever. The key issue seems to be Iron content of tap water. While Xtol uses a powerful sequestering agent (DTPA) to control the Fenton reaction, more Iron still means more remaining effect and less stability.

Click to expand...

My local water
I have a well
I don't use tap for anything

Spring No. 1, analyzed by Profs. Silliman and Norton—
..................................Grains.
...Sulphuric acid................134.732
...Proto-suiphate of iron.........28.623
...Sulphate of alumina............21.690
...Sulphate of lime...............74.891
...Sulphate of magnesia...........35.596
...Sulphate of potash..............5.519
...Sulphate of soda................6,343
...Chloride of sodium..............2.434
...Chloride of silica..............4.592
.....Total grains per gallon.....314.420

Spring No. 2, analyized by Prof. E. Emmons—
..................................Grains.
...Sulphate of lime................1.552
...Sulphate of magnesia............0.623
...Sulphate of iron................4.904
...Free sulphuric acid............16.132
...Free organic matter.............1.360
...Free silica.....................0.230
.....Total grains in a pint.......24.801

Spring No. 3, Analyzed by Prof. B. Emmons—
..................................Grains.
...Free sulphuric acid............12.414
...Sulphate of lime................0.736
...Sulphate of iron................3.920
...Sulphate of magnesia............1.236
...Organic matter..................0.100
...Silica a........................trace
.....Total grains in a pint.......18.406

A writer in the New York Journal of Commerce in July, 1849, gives the following “description of the Alabama Sour Springs:”

During my stay in Batavia I have visited the Oak Orchard Acid Spring, situated in the town of Alabama, about 14 miles from the village, 18 from Lockport, and 8 miles from Medina. The spring is in Tonawanda Swamp, on a little elevation, on which and in the immediate vicinity eight springs have been discovered, three of which are acid, one sulphur, one magnesia, one iron, and one gas spring sufficient to light 50 gas burners. The principal one is called “sour spring,” from which the celebrated Acid Water is taken, which is carried in great quantities to the Eastern cites, and many boxes sent to the Westenr States. About 25,000 bottles have been sold this past year at 25 cents per bottle. These springs are very highly recommended by Professor Emmons of Albany, Dr. Chilton of New York, and Professor R. Silliman, jr., of Yale College. Dr. Chilton says they contain of:
..................................Grains.
...Free sulphuric acid.............85.96
...Sulphate of lime................39.60
...Proto-suiphateof iron...........14.32
...Sulphate of alumina..............9.68
...Sulphate of magnesia.............8.28
...Silica ..........................1.04
...Organic extr active matter.......3.38
.....From one gallon..............160.62

Prof. Emmons remarks that “the peculiar character of these waters renders them useful in many chronic diseases especially those of the digestive organs and those of weakness and debility.” Dr. James McNaughton of Albany says: “The internal arid external use of these waters I have no doubt will prove valuable in the treatment of several chronic cutaneous diseases.” Dr. Robert Campbell of Pittsfield, Mass.. says: “As medical agents they must be highly beneficial for all chronic diseases of the stomach and bowels.” There are numerous other testimonials from eminent physicians. A good hotel has been erected by Messrs. J. C. Colton of Lockport and Thomas W. Olcott of Albany, which is kept in a very handsome manner by Messrs. Everett & Harrington, two industrious young men, who deserve and have received a very liberal patronage.

I'm a wino and I use wine box bladders and each batch holds for over a year.

Hmm. In my mixing, I have used tap water and not distilled -tried a nearby battery shop - but their distilled water was anything but.
I am seeing xtol turning deep blue. With usage. Working solution that is. Mixing it 1:3~
Also, is anyone experiencing that thesolution is getting evaporated with use -that happens even if stored in cool conditions, in shade? (relatively cool -current temps 27-8c in night and 35+c in daytime)

Sent from Tap-a-talk

The presence of an iron chelating agent in Xtol only slows oxidation by the Fenton reaction it does not completely stop it. Remember the reaction is dependent on the amount of iron (III) ions in the water. So those experiencing problems with tap water should use distilled or de-ionized water.

analoguey said:

I am seeing xtol turning deep blue. With usage. Working solution that is. Mixing it 1:3~

Click to expand...

Do you use a prewash? And if you use it 1:3, you use it single shot, yes?

analoguey said:

Also, is anyone experiencing that thesolution is getting evaporated with use -that happens even if stored in cool conditions, in shade? (relatively cool -current temps 27-8c in night and 35+c in daytime)

Click to expand...

What do you store your Xtol in? Some containers will allow for more evaporation losses than others ...

Gerald C Koch said:

The presence of an iron chelating agent in Xtol only slows oxidation by the Fenton reaction it does not completely stop it. Remember the reaction is dependent on the amount of iron (III) ions in the water. So those experiencing problems with tap water should use distilled or de-ionized water.

Click to expand...

Not experiencing problems with Xtol - negatives come out quite nice - I like they way they turn out actually. I don't know the process that you refer to - the Fenton reaction?

With sheet film, I do pre-wash, not with 120. 120 I go direct to developer.

Rudeofus said:

Do you use a prewash? And if you use it 1:3, you use it single shot, yes?

Click to expand...

Hmm, well I tried a bit of replenshing this time and it worked similarly as before, replenished with 100ml stock.

Rudeofus said:

What do you store your Xtol in? Some containers will allow for more evaporation losses than others ...

Click to expand...

Thats the thing, it evaporated when I was using it - in the tray! The initial volume I poured into the tray was much higher than the final volume poured *back* into the bottle!! In-storage no evaporation.

Developed at night, and only the xtol evaporated, not Dektol, not fixer. Not the water - well, okay I didnt measure that exactly.

Surely the sensible advice to ensure longevity of storage, regardless of what developer you are using, is to keep it in air tight containers prior to use.

I don't know the process that you refer to - the Fenton reaction?

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The Fenton reaction is a particular type of oxidation catalysed by iron and copper ions. In the worst case it can destroyed the ascorbate in Xtol in a matter of hours.

Right, thanks Gerald!
I dont see that happening here, but what I do see is the blue colouring - somewhat copper hue actually, like copper sulphate. Goes deeper with a bit of time and exposure to sun (in storage). But as of how, hasn't diminished in developing quality.
I will shoot some more B&W and see how it goes, right now, most of 120 and sheet developing is done unless I shoot immediately - so might try some later on.

You do realize that you lose quite a bit of developer due to carry over, yes? Take a precise scale, weigh one of your film sheets, then soak it in alkaline solution, then weigh it again. That's the amount of developer you lose every time you develop a sheet.

And about the blue color: look at the wash water if you prewash a roll of film. Without a prewash these dyes end up in your developer, are then changed by the Sulfite in your developer, but don't always go away completely. AFAIK these dyes do not interfere with development.

Rudeofus said:

sun of sand, the difference in stability can be easily explained by the difference in tap water across the globe. People from Australia report, that their Xtol goes bad within days, while yours evidently lasts forever. The key issue seems to be Iron content of tap water. While Xtol uses a powerful sequestering agent (DTPA) to control the Fenton reaction, more Iron still means more remaining effect and less stability.

Click to expand...

Who are these Australians of which you speak? It's a big country. Is it those pesky South Australians with their "hard" water. Most Australians live in big cities with "normal" water supplies. I have always stored my XTol in "wine" bladders (usually 5 litre ex "pure" water bladders) and have never had a problem. Has been perfectly fine after 2 years in one case. I prefer my wine from bottles.

Tony Egan said:

Who are these Australians of which you speak? It's a big country. Is it those pesky South Australians with their "hard" water. Most Australians live in big cities with "normal" water supplies. I have always stored my XTol in "wine" bladders (usually 5 litre ex "pure" water bladders) and have never had a problem. Has been perfectly fine after 2 years in one case. I prefer my wine from bottles.

Click to expand...

I have no idea whether Adelaide is a big town or a small hamlet, but Dr. Croubie and some Mr. polyglot both (there was a url link here which no longer exists) that their tap water kills Xtol. Since their water won't pass the metal detector for air transport, and I am afraid of standing upside down for prolonged periods, I have no way to confirm or deny this.

Rudeofus said:

I have no idea whether Adelaide is a big town or a small hamlet, but Dr. Croubie and some Mr. polyglot both (there was a url link here which no longer exists) that their tap water kills Xtol. Since their water won't pass the metal detector for air transport, and I am afraid of standing upside down for prolonged periods, I have no way to confirm or deny this.

Click to expand...

OK, that makes sense. Adelaide is special in so many ways, but not typical of the rest of Australia

Alessandro Serrao said:

...Xtol prepared on 2013/04 is still cristal clear and develops perfectly. That's 8 months.

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Isn't that 12 months?

Regarding the initial tests, pH makes a difference in the keeping qualities of just about any reductant. Sulfite is an antioxidant, and it also alters the pH.

PE

Yes, the production of the orange color might be pH dependent.
I hope to repeat the test later using sodium ascorbate solution buffered with borate to the same pH as the other solution that contained sulfite.
It is also an assumption that all the ascorbate is oxidized before the sulfite.

Rudeofus said:

sun of sand, the difference in stability can be easily explained by the difference in tap water across the globe. People from Australia report, that their Xtol goes bad within days, while yours evidently lasts forever. The key issue seems to be Iron content of tap water. While Xtol uses a powerful sequestering agent (DTPA) to control the Fenton reaction, more Iron still means more remaining effect and less stability.

Click to expand...

I'm pretty certain that the lifespan of XTOL is somehow related to water quality and maybe its iron content. I've used XTOL both in the USA and across Europe and have experienced a noticeable difference in lifespan depending on location.

It even seems to vary from building to building. When I was in Los Angeles living in a fairly old building I would constantly have problems with XTOL sudden death syndrome. After I moved to a newer building the problem went away.

I have also noticed that XTOL may not react well with some containers that are supposedly made from stainless steel. Therefore I have completely abandoned the use of metal with xtol, except for my actual developing tank, and switched to an all plastic workflow. Since then all seems well; at least in my current location.

Rudeofus said:

I have no idea whether Adelaide is a big town or a small hamlet, but Dr. Croubie and some Mr. polyglot both (there was a url link here which no longer exists) that their tap water kills Xtol. Since their water won't pass the metal detector for air transport, and I am afraid of standing upside down for prolonged periods, I have no way to confirm or deny this.

Click to expand...

Ha! Good one, Rudeofus! Maybe rotary processors go the wrong-way round, too. To be sure, I'm joking -- gotta get to Australia and New Zealand someday.

As a side thought, some say Fomadon Excel developer is an XTOL clone. Has anyone heard reports of Excel crashing suddenly? I note Excel is available in quart packets, so perhaps the developer tends to get used so quickly no one lets it sit around long enough to turn.

Tony Egan said:

. I have always stored my XTol in "wine" bladders (usually 5 litre ex "pure" water bladders) and have never had a problem. Has been perfectly fine after 2 years in one case. I prefer my wine from bottles.

Click to expand...

Good to know Tony. The tap water in my area of the U.K. is particularly hard. Limescale forms around tap openings and kettles need descaling quite frequently. Despite this or maybe because of it, I have usable Xtol in wine bladders that is now 17 months old based on a film developed end of last month. It may be I can look forward to 2 years as well. I intend to use the leader test each time and if it goes black to the extent of dimming the tungsten wires in a clear light bulb to the same extent as when almost new then I'll continue with it.

I'd urge anyone else to try wine bladders and the leader test

pentaxuser