Replenished Xtol getting weak over time

Donald Qualls · Oct 16, 2020

I agree, the six months figure suggests that even when fully airtight, Xtol will deteriorate over longer periods. However, I made a (very reasonable, I think) assumption about those figures: that within them, the process would still meet Kodak's criteria for in-use, in-date developer. That is, though the developer may have changed, the change would be within the "uncontrollable variation" level, where even a densitometer might not reliably detect fresh developer from your 5 1/2 month old full-bottle stock solution.

An example of "change" in the absence of oxygen is the well-known early aging of D-76 -- which gets stronger for a short time (a week, couple weeks?) after mixing. This is not the case with Kodak packaged developer, only with solution mixed from the published formula, and is due to pH changes in the fresh stock solution.

So, yes, developer changes properties even in perfect storage -- this is why it has a shelf life; this is why it's preferable (IMO) to buy powder developers or mix from raw chemicals than to buy liquid concentrates, But Kodak expects properly stored Xtol to last six months after mixing, and "opened and resealed, partly full" to last two months without deteriorating outside Kodak's original specs.

MattKing · Oct 16, 2020

Donald Qualls said:
So, yes, developer changes properties even in perfect storage -- this is why it has a shelf life; this is why it's preferable (IMO) to buy powder developers or mix from raw chemicals than to buy liquid concentrates, But Kodak expects properly stored Xtol to last six months after mixing, and "opened and resealed, partly full" to last two months without deteriorating outside Kodak's original specs.

And Kodak also expects working solution X-Tol used in a replenishment regime to last indefinitely, if replenishment with sufficiently active replenisher is done sufficiently regularly.
The magic word being "sufficient".
FWIW, I expect that regular replenishment even when no development has been done probably assists not because of the addition of fresh replenisher, but rather because it temporarily reduces the amount of development byproducts in the working solution, and thus offsets any reduced activity arising from the passage of time.

pentaxuser · Oct 16, 2020

Вormental said:
Donald, I agree with your reasoning. However, everything you said is based on one (big) assumption that developer properties do not change over time in the absence of oxygen. I doubt it as there must be solid reasons behind Kodak's stated lifespan of full-strength Xtol as "six months in full, tightly capped bottles". And that's for fresh/clean solution. Development byproducts only complicate the picture.

That may be what Kodak state but in the likes of winebags and this seems to apply to other reliable means of preventing oxidisation as reported by other members I get more like a year. I cannot say why Kodak states what it states but it may just be that it like other makers of chemicals is very conservative in its life of developer statements

pentaxuser

Sirius Glass · Oct 16, 2020

Вormental said:
@pentaxuser some people reported the need to replenish even if you don't develop, as the developer becomes less active over time. IIRC someone suggesting replenishing 70ml every two weeks even if you don't develop any film. I did not have this issue as my volume is pretty high.

Sealing and oxidation are a bigger problem.

removed account4 · Oct 16, 2020

koraks said:
Certainly; vitamin C developers are quite sensitive to iron impurities. Good call.

yup
and usually peoples water mains are made of Fe.
OP just add a little Dektol to it you will be fine.

Mainecoonmaniac · Oct 16, 2020

pentaxuser said:
That may be what Kodak state but in the likes of winebags and this seems to apply to other reliable means of preventing oxidisation as reported by other members I get more like a year. I cannot say why Kodak states what it states but it may just be that it like other makers of chemicals is very conservative in its life of developer statements

pentaxuser

I love wine bags. I keep my replenisher in the wine bag and my working solution in a plastic 2 liter jug. While processing my film in XTOL, I dispense the replenisher and pour 70 mils/ per roll jug holding the working developer. Then I pour the used developer back into the jug until it’s topped off and I toss what’s left over. There’s no air in both the replenisher bladder and the working developer jug. As I mentioned, my developer gets weak over time.

MattKing · Oct 16, 2020

Maybe you are drinking the wrong wine!

Mick Fagan · Oct 16, 2020

Maris said:
I mixed my Xtol stock in 2007 and have replenished at the rate of 90ml per standard film ever since. For many years my development time for Tmax 400 @68F has been consistent at 11min 15sec. This is definitely weaker than Kodak's recommendation of 7min 15sec but I suspect replenished Xtol activity settles to higher or lower value depending on replenishment rate.

Maris, I read this as, you mixed your original developer in 2007 and are still running the same developer bath with replenishment, is this correct?

Mick.

mshchem · Oct 16, 2020

Donald Qualls said:
One way to check if it's actually bad replenisher (since it's the same as original working solution) is to process a strip of film in the replenisher directly. If that also comes up thin (or maybe extremely thin) then you've mixed a bad batch of replenisher (and your filtering is likely to blame for one reason or another).

Yep, this is a great idea.

mshchem · Oct 16, 2020

Sirius Glass said:
Modelling the chemical behavior is interesting but it does nothing to find out why a minority of people have the weakening problem. I have used replenished XTOL following the instructions exactly for over a decade and like the vast majority I have not had a problem.

Me too. Pure water, full bottles. Since I got Joboized I use mostly one shot, but I wouldn't be afraid to use replenished straight XTOL in a Jobo. It was designed to accommodate big processors. I just wonder if it's the iron thing in water? ?

There's so much dissolved minerals in my tap water, you simply can't get all the sulfite dissolved. I've been on RO since 1996.

mshchem · Oct 16, 2020

I'm sorry I didn't think to get this witnessed. If I start now I will be able to confirm in 2031.

https://www.photrio.com/forum/threads/xtol-11-year-old-stock-solution-worked.146101/

Maris · Oct 17, 2020

Mick Fagan said:
Maris, I read this as, you mixed your original developer in 2007 and are still running the same developer bath with replenishment, is this correct?

Mick.

My first Xtol batch ran with regular replenishment from 1998 to 2006 when it was put into storage for 18 months when I had no darkroom. On testing in 2007 it had lost half its activity so I discarded it.
The current stock bottle of Xtol was started in 2007 and has seen continuous use ever since at a replenishment rate of 90ml per standard film. The only extra process I do is to pre-wash all films to prevent antihalation dye, acutance dye, speed trimming dye, and sensitising dye accumulating in my (very) well seasoned Xtol.

Donald Qualls · Oct 17, 2020

Maris said:
My first Xtol batch ran with regular replenishment from 1998 to 2006 when it was put into storage for 18 months when I had no darkroom. On testing in 2007 it had lost half its activity so I discarded it.
The current stock bottle of Xtol was started in 2007 and has seen continuous use ever since at a replenishment rate of 90ml per standard film. The only extra process I do is to pre-wash all films to prevent antihalation dye, acutance dye, speed trimming dye, and sensitising dye accumulating in my (very) well seasoned Xtol.

That's impressive. I've only been replenishing for a couple months, mine is a little blue because I forgot to prewash my Fomapan 400 (120 size) once, but that'll dilute away over time. About how much film (rolls per month) do you process?

Raghu Kuvempunagar · Oct 17, 2020

Maris said:
The only extra process I do is to pre-wash all films to prevent antihalation dye, acutance dye, speed trimming dye, and sensitising dye accumulating in my (very) well seasoned Xtol.

@Maris: I'm curious to know if you pre-wash in distilled/RO water. A little bit of water from the pre-wash goes into the developer and over a period of time there's accumulation. If you used tap water for pre-wash and you never saw the developer deteriorating, it probably means the fear of trace iron from tap water affecting the developer is exaggerated.

Donald Qualls · Oct 18, 2020

Kodak's fix for the iron problem (Fenton reaction, which destroys dissolved organics like phenidone and especially ascorbate) was an iron sequestering agent, as I recall -- it sucks up the iron from the water -- as well as respecifying their feedstocks to lower/eliminate iron and copper impurity (low enough for the sequestration agent to deal with). Xtol made after approximately 2000 is supposed to be free of this problem even when mixed with tap water (all of Kodak's commercial products are designed to tolerate tap water for both concentrate/stock mixing and dilution).

Sirius Glass · Oct 18, 2020

My water is hard with plenty of iron and I have never had a water problem with XTOL. Accordion bottle leaking are yes, but not a water problem.

Вormental_old · Oct 18, 2020

Quick update: I followed Donald's recommendation and mixed the fresh 5L batch at a higher temperature. I used 83F, still within Kodak's recommended range. Compared to my regular usage of room temperature water @ 68-70F, it was significantly easier to dissolve both packets, in fact they fully dissolved in the 4L before I even topped it to 5L. No floaters whatsoever.

Sirius Glass · Oct 18, 2020

Maris · Oct 18, 2020

Raghu Kuvempunagar said:
@Maris: I'm curious to know if you pre-wash in distilled/RO water. A little bit of water from the pre-wash goes into the developer and over a period of time there's accumulation. If you used tap water for pre-wash and you never saw the developer deteriorating, it probably means the fear of trace iron from tap water affecting the developer is exaggerated.

Tap water only, never RO or distilled water. The company that supplies tap water here, Seqwater, reports iron content below 0.01 ppm. No problems with Xtol.

Maris · Oct 18, 2020

Donald Qualls said:
That's impressive. I've only been replenishing for a couple months, mine is a little blue because I forgot to prewash my Fomapan 400 (120 size) once, but that'll dilute away over time. About how much film (rolls per month) do you process?

About 20 roll "equivalents" a month as a mix of 8x10 sheet, 4x5 sheet, and 120 roll film.

Donald Qualls · Oct 18, 2020

Okay. I wish I could shoot and process that much. But now we have a data point -- 20 rolls a month = 1.6L per month of replenishment. Know to be sufficient to keep Xtol going indefinitely.

Replenished Xtol getting weak over time

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