Replenished Xtol getting weak over time

Вormental_old · Oct 15, 2020

Just wanted to share in case someone finds this useful.

I started my replenished Xtol batch many rolls ago, as I am on my 3rd Xtol bag (i.e. I consumed almost 15L of it) and it's been stable with the first two bags, but as I mixed the last bag, things haven't been the same.

Every development session I see thinner and thinner negs. At first I assumed user error, perhaps the wrong temperature or lazier than usual agitation. Then I increased my replenishment rates to 100ml per roll, and I am still not back to normal, despite being surgically precise with my times, temps and agitation.

Last night I finally forced myself to admit the problem and started thinking about the last bag. I compared batches/dates and they're identical (I purchased 4 bags at the same time in January). They're stored in a dry storage bin at 60-70F. They are not expired, so I have no reason to suspect faulty chems.

However, when I mixed the last batch, I did something new: I used the coffee filter to "clear up" the developer as it had a few undissolved floaters. I always had some when mixing Xtol, but I allowed them In the past. The filter was quite tight and it took a long time for all 5L to go through it, as the flow was restricted resulting in a weak stream. Basically I suspect that I pre-oxidized all 5L. And now, as I'm replenishing with this "aerated" Xtol, my working batch is getting weaker.

Possible? Is oxidation a gradual process? I will be mixing a fresh batch and seasoning it anyway, and I won't be using these filters, but figured it's worth sharing/asking here.

Donald Qualls · Oct 15, 2020

Very possible, especially if you hadn't mixed the B bag yet when you filtered the floaters. All (or virtually all) the sulfite is in Bag B. The phenidone and ascrobate are in Bag A, so a long time and dripping a thin stream through air before adding the sulfite could result in significantly weakening the solution.

Also, if the filter you used had iron or copper in either the paper or the funnel section, that could have led to destruction of the ascorbate (though that's usually an abrupt, rather than gradual failure, but if all the new replenisher was failed, the working solution would get gradually weaker from the combination of exhaustion and dilution).

Mainecoonmaniac · Oct 15, 2020

I use replenished XOL and it's the same thing for me. I have the working solution in a 1/2 gallon container and the replenishment solution in a recycled wine bladder. I always top off the working solution bottle so there's no air. After a while, the developer drifts weaker. Since the replenisher and the working solution is the same, you can replenish more than the recommended 70mls per roll. I think all developers may become weaker due to bromide build up. I also used HC-110 replenished and I replenished the recommended rate and it got weaker over time. I just tossed it and made a fresh batch. I like the look of film processed seasoned developers.

MattKing · Oct 15, 2020

Mainecoonmaniac said:
I think all developers may become weaker due to bromide build up.

That is why you need to increase the replenishment amount - in addition to adding new developer, replenishment removes development byproducts such as bromides.
HC-110 replenishment was designed to extend life of the developer - the replenishment regime requires much smaller amounts of replenisher for each roll, and the manufacturer's instructions specify discarding the working solution after a period of time. Here is what the datasheet for HC-110 says:
Process Control
When replenishing tank solutions, monitor the developer
activity with KODAK Black-and-White Process Control
Strips. Depending on the utilization, you can use a tank
solution for up to one month if the control strips indicate
proper developer activity.
If you don’t use control strips, discard the tank solution
when you have —
• Replenished the solution for two weeks;
• Added an amount of replenisher that equals the original
volume of the working solution; or
• Processed fifty 20.3 x 25.4 cm sheets per litre (two
hundred 8 x 10-inch sheets [or equivalent] per gallon) of
developer.

In contrast the datasheet (J109) for X-Tol does not suggest that a properly maintained working solution will need to ever be discarded:

You can replenish this developer in systems that use the
full-strength solution (not diluted developer). Use XTOL
Developer as a replenisher at a rate of 70 mL for each
135-36 or 120 roll, or the equivalent of 80 square inches
(516 square centimetres), of film processed.
You can monitor replenished systems with KODAK
Black-and-White Film Process Control Strips
(CAT 180 2990). Adjust the replenishment rate up or
down in 10 mL increments to keep the process on aim.
Allow adequate time for the process to stabilize between
replenishment-rate adjustments. Use the lowest
replenishment rate that will maintain process control. For
more information, see Kodak Alaris Publication No.
Z-133E, Monitoring and Troubleshooting KODAK Black-and-
White Film Processes (CAT 889 4784).
KODAK PROFESSIONAL XTOL Developer • J-109 5
System Maintenance
KODAK PROFESSIONAL XTOL Developer is very
clean-working, and will rarely need replacement in a
properly replenished and maintained process.
Take these steps for routine maintenance:
• Minimize air access to the replenisher tanks. Use
floating lids.
• Use a small amount of water to rinse the developer
from processor parts left exposed to air after
shutdown.
• Replace evaporation losses with water at processor
start-up.
• If your processor is equipped with recirculation filters,
check them frequently, and change them as needed.

Sirius Glass · Oct 15, 2020

After a year or two I will dump the replenished XTOL and start over.

koraks · Oct 15, 2020

Вormental said:
However, when I mixed the last batch, I did something new: I used the coffee filter to "clear up" the developer as it had a few undissolved floaters. I always had some when mixing Xtol, but I allowed them In the past. The filter was quite tight and it took a long time for all 5L to go through it, as the flow was restricted resulting in a weak stream. Basically I suspect that I pre-oxidized all 5L.

I suspect you filtered out the phenidone/dimezone (whichever they use). Its the component that takes the longest to dissolve in this mix.
Try not filtering.

Donald Qualls · Oct 15, 2020

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).

Andrew O'Neill · Oct 15, 2020

I always left those little floaties alone...

Sirius Glass · Oct 15, 2020

Andrew O'Neill said:
I always left those little floaties alone...

Me too.

Вormental_old · Oct 15, 2020

Very helpful as always, thanks guys. A few comments:

I doubt that my replenisher is completely dead, as I've gone through 3L of it, i.e. my 1.8L working batch at this point is 100% from the last bag.
The coffee filter had no metal elements, just unbleached paper.
The replenisher is crystal clear. I mean too clear almost like water. In the past, Xtol always looked a bit muddy. I definitely removed a lot with the filtration.

Athiril · Oct 15, 2020

I ran a lot of Xtol and didn’t run into that, you filtered out undissolved developer agent by the sounds of it. I filtered my replenished Xtol solution when it started to get cloudy or grey and it got crystal clear after (and a dirty coffee filter). No impact on negs, but everything was fully dissolved. I also mixed Xtol up in tap hot water to start with and a lot of stirring with a paddle.

I had that issue with parodinal and filtering it to clear it up of undissolved matter, it was 50% strength versus commercial Rodinal etc.

Donald Qualls · Oct 15, 2020

It takes much more than 100% volume replenishment to completely replace the developer. Each time you replace 70ml of the 1.8L working solution, you do approximately a 4% replacement. This will only exponentially reduce the amount of original solution present -- what power of 96% (the fraction of remaining original solution) reaches zero? It takes 33 replenishments (2.3 L) to get down to 25% original solution. If we presume that the replenisher still has the ascorbate and only lost the phenidone, your working solution, at that point, has about 25% of its original phenidone content but 100% of original ascrobate level. That's why your film isn't completely clear (ascorbate alone is a pretty weak developer, but it's super-additive with most metol/phenidone derivatives). You've essentially created a low-contrast developer suitable for pictorial use of document films (Tech Pan, ImageLink HQ/HR, Copex Rapid, etc.).

The practical way to fix this at this point is to mix fresh Xtol and season a new working batch, as you propose -- but now you know something not to do.

FWIW, I had no floaties when I mixed mine, but I mistakenly used water at around 115F. Doesn't seem to have done any harm...

PFGS · Oct 15, 2020

MattKing said:
That is why you need to increase the replenishment amount - in addition to adding new developer, replenishment removes development byproducts such as bromides.

No idea if this has anything to do with @Bormental 's batch weakening, but when I first started my own use of Xtol-R, I realized that the ratio of tank size to number of rolls developed has a lot of impact on how long it will take for the batch to stabilize at a given concentration of byproducts, and what that concentration will be. Not a point I've seen mentioned much, and quite possibly a source of variation.

Вormental_old · Oct 15, 2020

@PFGS, true. I did not mention it as I have settled on my replenishment amounts during the previous 10L and they've been very stable for me, especially after I moved to a bigger working bottle, I think we talked about this before. I used to do 75-80ml for 120 rolls and 60-70ml for 25exp 135 rolls (bulk-loaded). The reason I'm using ranges is simply because I use 250ml bottles to store the replenisher, and sometimes it's just easier to empty one.

Arvee · Oct 15, 2020

Same thing happened to me. I use brown glass 750ml wine bottles with VacuVin stoppers so I can evacuate all air after opening. After six weeks or so the negs were getting noticeably thinner and the light struck leaders were fading too. That's when I got smart and stopped using a developer that was sabotaging my negs. Not reliable!

I think this happens fairly often but most folks don't have a densitometer to measure the degradation and they don't realize what's really happening thinking it may be a pilot error in exposure when the negs become so difficult to print. Scanners, however, will compensate and cover up the underdevelopment until it becomes too severe to correct.

Why use a developer that isn't consistent or reliable? Makes no sense to me. I went back to reliable D-76 mixed from scratch.

Mainecoonmaniac · Oct 15, 2020

MattKing said:
That is why you need to increase the replenishment amount - in addition to adding new developer, replenishment removes development byproducts such as bromides.
HC-110 replenishment was designed to extend life of the developer - the replenishment regime requires much smaller amounts of replenisher for each roll, and the manufacturer's instructions specify discarding the working solution after a period of time. Here is what the datasheet for HC-110 says:
Process Control
When replenishing tank solutions, monitor the developer
activity with KODAK Black-and-White Process Control
Strips. Depending on the utilization, you can use a tank
solution for up to one month if the control strips indicate
proper developer activity.
If you don’t use control strips, discard the tank solution
when you have —
• Replenished the solution for two weeks;
• Added an amount of replenisher that equals the original
volume of the working solution; or
• Processed fifty 20.3 x 25.4 cm sheets per litre (two
hundred 8 x 10-inch sheets [or equivalent] per gallon) of
developer.

In contrast the datasheet (J109) for X-Tol does not suggest that a properly maintained working solution will need to ever be discarded:

You can replenish this developer in systems that use the
full-strength solution (not diluted developer). Use XTOL
Developer as a replenisher at a rate of 70 mL for each
135-36 or 120 roll, or the equivalent of 80 square inches
(516 square centimetres), of film processed.
You can monitor replenished systems with KODAK
Black-and-White Film Process Control Strips
(CAT 180 2990). Adjust the replenishment rate up or
down in 10 mL increments to keep the process on aim.
Allow adequate time for the process to stabilize between
replenishment-rate adjustments. Use the lowest
replenishment rate that will maintain process control. For
more information, see Kodak Alaris Publication No.
Z-133E, Monitoring and Troubleshooting KODAK Black-and-
White Film Processes (CAT 889 4784).
KODAK PROFESSIONAL XTOL Developer • J-109 5
System Maintenance
KODAK PROFESSIONAL XTOL Developer is very
clean-working, and will rarely need replacement in a
properly replenished and maintained process.
Take these steps for routine maintenance:
• Minimize air access to the replenisher tanks. Use
floating lids.
• Use a small amount of water to rinse the developer
from processor parts left exposed to air after
shutdown.
• Replace evaporation losses with water at processor
start-up.
• If your processor is equipped with recirculation filters,
check them frequently, and change them as needed.

Thanks Matt. Makes sense. How about mixing some of the old season developer into the fresh batch?

MattKing · Oct 15, 2020

Arvee said:
I think this happens fairly often but most folks don't have a densitometer to measure the degradation and they don't realize what's really happening thinking it may be a pilot error in exposure when the negs become so difficult to print. Scanners, however, will compensate and cover up the underdevelopment until it becomes too severe to correct.

Could be, but there are lots of us who darkroom print and use replenished X-Tol with success - we don't see it happening.
I'm guessing people under-correct if and when they see a change. I would recommend that if 70 ml isn't doing the job, jump up to 100 ml. Then, after a few rolls of that, if you want to maximize economy, consider lowering the amount slowly.

PFGS · Oct 15, 2020

Вormental said:
@PFGS, true. I did not mention it as I have settled on my replenishment amounts during the previous 10L and they've been very stable for me, especially after I moved to a bigger working bottle, I think we talked about this before. I used to do 75-80ml for 120 rolls and 60-70ml for 25exp 135 rolls (bulk-loaded). The reason I'm using ranges is simply because I use 250ml bottles to store the replenisher, and sometimes it's just easier to empty one.

Yep - we did, and I've been using your method with good results, though I am still on my first 5L. But what I'm referring to is not replenishment amounts, but how the developer is used.

Say we define a unit "B" where 1 B = "the development byproducts from one roll of film" - we can then express the seasoning of our Xtol-R as B per liter. For easy math, lets say we replenish at 100ml per roll, and we are starting with a 2000ml bottle of brand new, fresh Xtol stock that will become our Xtol-R and compare two scenarios. For simplicity I'm going to pretend we replenish after the very first development session, I know we don't but the end principle is the same:

1) We pour 1000ml of the Xtol into a dev tank with two rolls of film, and while we develop, we add to the 1000ml left in the storage jug our 200ml (100ml x 2 rolls) of replenishment. We then need to top up the jug with 800ml of used Xtol from the dev tank and toss the rest down the sink. The dev tank will contain 2B of dev byproducts, we pour 1.6B of that back into the jug when we top up, and are left with 2000ml of Xtol-R at a seasoning concentration of .8 B/L.

2) We pour 500ml of the Xtol into a dev tank with two rolls of film, and while we develop, we add to the 1500ml left in the jug our 200ml (100ml x 2 rolls) of replenishment. This time, to top up, we need to fill the jug with 300ml of used Xtol from the dev tank and again toss 200ml down the sink. The dev tank will again contain 2B of dev byproducts, but this time only 1.2B will accompany what we pour back in, and we are left with 2000ml of Xtol-R at a seasoning concentration of .6 B/L.

I was bored enough one day to write a short script in PHP to reiterate this process, and was surprised to see that at an 80ml per roll replenishment, B/L takes a lot of time to stabilize and ends up at a full 2 B/L difference between the two scenarios above - which represent how I typically develop 120 vs 35mm. Two 120 rolls in 1 liter stabilizes at 10.5 B/L, and two 35mm rolls in 500ml stabilizes at 8.5 B/L. There may not be a significant difference between those two numbers, but they are quite different from the B/L of the first few sessions.

I guess the main takeaway is, we might expect that it can keep getting weaker for a long time without there necessarily being a problem.

Вormental_old · Oct 15, 2020

Ah, I see what you're saying now. My observation is that B units do not correspond linearly to development speed/contrast. As you begin seasoning (B is small) the developer activity is dropping quickly, but as B grows the difference becomes less pronounced, this relationship seem logarithmic to me (as so many things in the analog domain!)

Вormental_old · Oct 15, 2020

Arvee said:
I think this happens fairly often but most folks don't have a densitometer to measure the degradation and they don't realize what's really happening thinking it may be a pilot error in exposure when the negs become so difficult to print. Scanners, however, will compensate and cover up the underdevelopment until it becomes too severe to correct.

Why use a developer that isn't consistent or reliable? Makes no sense to me. I went back to reliable D-76 mixed from scratch.

I cannot comment on your experience, but I do want to point out that my first two batches were absolutely fine, with zero degradation. I do not own a densitometer but I can attest to development consistency by looking at my Capture One presets (I "scan" with a constant-exposure SLR) where I can clearly see black/white points and exposure & gamma correction required for contrast to my taste.

You have a point though. Replenishment by definition requires predictable volume, and I will be the first to recommend full-strength Xtol to casual film shooters. But at 2-4 rolls a week, I think my volume is sufficient to keep the working batch "hot" and make it economically viable.

[edit] Just noticed your D76 comment. Nothing against D76, but why blame Xtol for replenishment failure? One-shot Xtol is also a good option.

MattKing · Oct 15, 2020

PFGS said:
2) We pour 500ml of the Xtol into a dev tank with two rolls of film, and while we develop, we add to the 1500ml left in the jug our 200ml (100ml x 2 rolls) of replenishment. This time, to top up, we need to fill the jug with 300ml of used Xtol from the dev tank and again toss 200ml down the sink. The dev tank will again contain 2B of dev byproducts, but this time only 1.2B will accompany what we pour back in, and we are left with 2000ml of Xtol-R at a seasoning concentration of .6 B/L.

I think you missed two things when you did this calculation.
1) When you add the 500 ml of (partially) seasoned X-Tol to this second tank, that 500 ml has 0.4 B of development byproducts already in it. So after developing the film, the tank has 2.4 B in it (not 2B), and 60% (1.44 B, not 1.2B) of that goes back into the 2000 ml of Xtol-R;
2) when you pour that 300 ml (containing 1.44B) back into the 2000 ml working solution tank, the total amount of B in that tank is 1.2 B + 1.44B = 2.64B. That tank then has a seasoning concentration of 2.64B/2 = 1.32B/litre.

PFGS · Oct 15, 2020

Вormental said:
Ah, I see what you're saying now. My observation is that B units do not correspond linearly to development speed/contrast. As you begin seasoning (B is small) the developer activity is dropping quickly, but as B grows the difference becomes less pronounced, this relationship seem logarithmic to me (as so many things in the analog domain!)

Agreed, I found it surprising that B/L takes so long to stabilize, but I wouldn't find it at all surprising that the relationship isn't linear.

PFGS · Oct 15, 2020

MattKing said:
I think you missed two things when you did this calculation.
1) When you add the 500 ml of (partially) seasoned X-Tol to this second tank, that 500 ml has 0.4 B of development byproducts already in it. So after developing the film, the tank has 2.4 B in it (not 2B), and 1.44 B (not 1.2B) of that goes back into the 2000 ml of Xtol-R;
2) when you pour that 300 ml (containing) 1.44B) back into the 2000 ml working solution tank, the total amount of B in that tank is 1.5 B + 1.44B = 2.94B. That tank then has a seasoning concentration of 2.94B/2 = 1.47B/litre.

The two scenarios are meant to be parallel, not sequential - both start with unseasoned Xtol stock. And in my actual PHP model, both get properly seasoned at the start, not replenished on the first go.

Donald Qualls · Oct 15, 2020

PFGS said:
I guess the main takeaway is, we might expect that it can keep getting weaker for a long time without there necessarily being a problem.

What I'd consider "the next question" then is how much B does it take to make a visible (not measurable, since some people can -- or claim they can -- measure a gnat's whisker at a hundred paces) difference in the negatives? The B factor reasonably includes some level of exhaustion, oxidized developer products, dyes from films (for those who don't pre-soak), bromide, and various other things -- but at some point, as noted, it stabilizes; the lower your replenishment level, the higher the stable B value. If you process a mix of 35mm and 120, or (as I do) double load your 120 so a liter of developer gets four rolls, it'll stabilize at some value between the all-35mm, stainless tank value, and the all-120, Paterson tank, one roll per reel value -- even mine, since I don't always have an even number of 120 rolls that need the same time, so I wind up with one, or three, thus less film per liter.

BUT! If that end result, some level of B that we might reasonably expect to run (at 70ml/roll recommended replenishment) somewhere between 13 and 17 B/L, produces consistent negatives, who cares? Aside from the fact your developer might not be fully seasoned until sometime after you mix your second 5L of replenisher...

@Bormental and I have gone back and forth about the difference between him having to add a bunch of time on a specific film and still losing speed -- and me not having to do so and getting good shadows at box speed. It might well be partly due to his much higher processing volume; my developer (with only a bit over a liter of replenisher consumed) likely isn't even really seasoned yet (since I have 2L of working solution, and started replenishing from roll 1, expecting to adjust development when and as needed -- and it hasn't been needed yet), and his, on the third bag of mix, is (was, before the filter incident).

MattKing · Oct 15, 2020

PFGS said:
The two scenarios are meant to be parallel, not sequential - both start with unseasoned Xtol stock. And in my actual PHP model, both get properly seasoned at the start, not replenished on the first go.

We cross posted - I corrected two numbers before you posted.
But generally speaking, in order to analyze your model, can you indicate how you dealt with the next step in each of the two parallel models - which I did initially misunderstand to be sequential).

Replenished Xtol getting weak over time

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