Progress on XTOL-concentrate

[Dave Krueger]

I mixed a new batch of XTOL a couple of days ago, storing it in five 1-litre bottles. And I thought of a way of making it last longer: Store the extra bottles in the refrigerator. Sulfite will precipitate out of solution, but when it's time to start a new bottle, warming and shaking it should bring the precipitate back into solution. Kirk Keys reminded me that chemical reactions proceed half as fast with each 10C temperature-drop, so refrigeration should make XTOL last around 1.5-2 years instead of 6 months. Is there any reason why this would not work?

Mark Overton

Hmmm.... I routinely store Xtol in full 1 liter bottles in a fridge. I take them out several days before I use them. I haven't noticed any obvious problems in my negatives from doing this, but I didn't know that the sulfite precipitates out. My bottles aren't clear, so I wouldn't be able to see it. I'm not really a chemist, but doesn't sulfite act as a preservative? If so, then the fact that it precipitates out doesn't sound like a good thing. Also, I'm guessing that the lower sulfite level might impact the apparent size of the grain.

 

[albada]

Hmmm.... I routinely store Xtol in full 1 liter bottles in a fridge. I take them out several days before I use them. I haven't noticed any obvious problems in my negatives from doing this, but I didn't know that the sulfite precipitates out. My bottles aren't clear, so I wouldn't be able to see it. I'm not really a chemist, but doesn't sulfite act as a preservative? If so, then the fact that it precipitates out doesn't sound like a good thing. Also, I'm guessing that the lower sulfite level might impact the apparent size of the grain.

As a result of your posting, I put a 1L bottle of XTOL in the fridge last night. This morning, it had a thin layer of precipitate on the bottom which, upon disturbing the bottle, broke up and floated around in the fluid, looking like pieces of shredded tissue. Both of my prior batches of XTOL have done this at room temperature over a couple of months, so refrigeration sped-up that process. I'm leaving it in the fridge to see how much precipitate forms.

Mark Overton

 

[kb3lms]

Both of my prior batches of XTOL have done this at room temperature

I have seen this as well. I've been using my XTOL replenished so I had thought it might be buildup of some residue after many rolls, so I filtered it out. Have not noticed any effects one way or another from filtering.

Your developer looks really interesting. I've been watching this thread over the last few months and have gradually acquired all the ingredients. The last of my XTOL is gone now, so I'm going to be making up a batch of this formula to try it out.

So, looks like some great work you've done. Thank you for sharing!

-- Jason

 

[Mike Bates]

As a side note, I store 5L of Xtol using the same means as the box-o-wine.

The Fermtech "Wine on Tap" system consists of a sanitized oxygen barrier bag with a push-button dispensing spout and plastic shell that provides the "box" structure. The plastic shell and one bag costs about $23 and replacement bags are 3/$10.

After the Xtol is mixed, use a funnel to fill the bag and snap the push-button dispenser on. (Don't snap the dispenser on until the bag is full. It's meant to be disposed of with the used bag and nearly impossible to remove without damage.) Orient the dispenser on top and gently squeeze the bag while pushing the button to expel any air. There shouldn't be much. Then set it upright and you're good to go.

Dispensing into a graduated cylinder is easy with the push-button and the bag collapses around the remaining Xtol with no air pocket.

I have no trouble using 5L in six months, so I don't know how long Xtol will store this way. It should be good for quite a while, though.

 

[Dave Krueger]

As a result of your posting, I put a 1L bottle of XTOL in the fridge last night. This morning, it had a thin layer of precipitate on the bottom which, upon disturbing the bottle, broke up and floated around in the fluid, looking like pieces of shredded tissue.

Mark Overton

Uh-oh.... I've seen that shredded tissue look before back when I was using amber glass bottles to store Xtol in the fridge. I thought is was some kind of residue from manufacturing the bottle. I figured it would be gone next time I used the bottles, but then switched to barrier bottles, so I completely forgot about it.

Dammit. And I thought I was being so clever by storing it in full 1 liter bottles in the fridge. Well, it's nice to know the truth anyway. I'll leave them out of the fridge from now on. Thanks for the insight, Mark.

 

[albada]

As a side note, I store 5L of Xtol using the same means as the box-o-wine.
The Fermtech "Wine on Tap" system consists of a sanitized oxygen barrier bag with a push-button dispensing spout and plastic shell that provides the "box" structure. The plastic shell and one bag costs about $23 and replacement bags are 3/$10.
After the Xtol is mixed, use a funnel to fill the bag and snap the push-button dispenser on. (Don't snap the dispenser on until the bag is full. It's meant to be disposed of with the used bag and nearly impossible to remove without damage.) Orient the dispenser on top and gently squeeze the bag while pushing the button to expel any air. There shouldn't be much. Then set it upright and you're good to go.
Dispensing into a graduated cylinder is easy with the push-button and the bag collapses around the remaining Xtol with no air pocket.
I have no trouble using 5L in six months, so I don't know how long Xtol will store this way. It should be good for quite a while, though.

This is a good idea!

I would give you one caution though: You'll notice from nearby postings by kb3lms, Dave Krueger and myself that XTOL tends to form a thin film of precipitate on the bottom after storage for a few weeks or a couple of months. Since your tap is on the bottom, any precipitate will come out first. So if it's been a few weeks since you dispensed some XTOL, I suggest examining the beaker for bits floating around.

Mark Overton

 

[Alan Johnson]

After more experimenting, I've come up with the formula below. Its grain is slightly better than XTOL, sharpness is the same, and dev-times are longer. The 1-litre formula for mixing directly into water:

Sodium sulfite ................. 45 g
Sodium metaborate ........ 2 g
Ascorbic acid .................. 4.5 g
Phenidone ...................... 0.05 g
Target pH = 8.05 to 8.10.
13:40 minutes for TMY2.
​

For a concentrate, mix everything except sulfite into 16 ml of propylene glycol.

Mark Overton

Is it needed to multiply the weight of metaborate by 1.354 (see post 85) if 8-mol metaborate is supplied?
Is there an approximate multiplier of Xtol time for development?

 

[polyglot]

Once you dilute the Xtol to 1+1, the shredded-tissue stuff goes back into solution and it's all good. It's not good to use as stock because you'll get dense spots on the film.

I use the bag-in-box method, though I just buy a 10L box of drinking water (low iron, unlike our tap water), use that to make up the developer and put it back in the bag.

There is some oxidation in a sealed container due to oxygen already dissolved in the water. You could boil the water first to degas it but I just make my Xtol up at higher concentration (1.25x, i.e. 5L pack into 4L), which reduces the O2 content by 20%. I think I've seen a report on APUG that it will dissolve in 3L.

 

[Mike Bates]

This is a good idea!

I would give you one caution though: You'll notice from nearby postings by kb3lms, Dave Krueger and myself that XTOL tends to form a thin film of precipitate on the bottom after storage for a few weeks or a couple of months. Since your tap is on the bottom, any precipitate will come out first. So if it's been a few weeks since you dispensed some XTOL, I suggest examining the beaker for bits floating around.

Mark Overton

The tap is actually an inch or so above the bottom, so I'd have to tip the bucket to get the last of the Xtol. I dispense into a clear graduated cylinder and add water to make a 1:1 solution. I've never seen any precipitate in the solution. I mix the stock solution with heat distilled water to avoid any extra minerals that may precipitate out. I understand some people have seen some in spite of that.

In reality, there might be a little precipitate in the bottom of the bag and I wouldn't notice it. Xtol is pretty cheap, so when it starts getting low, I mix a new batch and store it in a new bag waiting to be installed in the bucket. I rarely try to drain the old back completely dry because of the potential for dregs at the bottom.

Keep up the good work. I'm a big fan of Xtol and your work may lead to a perfect (or better!) substitute if Kodak eventually stops making it.

mike

 

[MattKing]

Here is a Canadian source for this dispenser - it may in fact be where it originates: http://www.winemakeri.com/Wine_dispenser_p/17132.htm

With respect to the precipitate, it seems to me that if one is using X-Tol in a replenishment regime, small amounts of precipitate in the replenisher solution are unlikely to be a problem, so the dispenser should be perfect for it.

 

[albada]

Is it needed to multiply the weight of metaborate by 1.354 (see post 85) if 8-mol metaborate is supplied?
Is there an approximate multiplier of Xtol time for development?

Hello Alan,

This developer is the same as your D316, except that the metaborate is 2.0 g/L instead of 2.2 g/L. The slightly lower pH means the times will need to be lengthened a bit from D316. For TMY2, the multiplier is 2.19, but that assumes it's formulated as a concentrate. The PG in a concentrate slows development a little, hence a slightly longer time.

And yes, I assumed the use of metaborate 4-mol (dihydrate), so 8-mol will need more.

BTW, if you want to use D316, you can add 40 g/L of sulfite instead of 45, and that will give similar results and the same times as above. I tested 40 g/L with D316, and the grain matches XTOL. This new brew has a hint finer grain, but I suspect most folks would not consider the improvement to be significant.

Yesterday, I tested 50 g/L of sulfite and dropping the metaborate to 1.8 g/L to keep pH unchanged. My preliminary results give an XTOL time-ratio of 2.15, slightly finer grain, and slightly lower true speed (1/5 stop speed-loss). The appearance of the grain is also more attractive due to fewer worms, so this is a promising brew.

Mark

 

[albada]

Keep up the good work. I'm a big fan of Xtol and your work may lead to a perfect (or better!) substitute if Kodak eventually stops making it.
mike

Mike and Jason: Thanks for the encouragement. My original motive for creating a concentrate was to avoid waste because we occasional shooters can't use 5 litres in 6 months. But Kodak's bankruptcy has heated the fire under me. I love XTOL, and want to be certain a proven replacement is available in case Kodak's B&W division is dismantled.

Mark Overton

 

[kb3lms]

...want to be certain a proven replacement is available in case Kodak's B&W division is dismantled.

Not only that, though. I've started reading photo journals and magazines from the late 1800's, ie pre-Kodak. In fact, one issue from 1884 gave details of one of Eastman's original patent submissions. Another article I read was about going out for a demonstration (we'd call it a review today) of the original Kodak box camera with 100 exposures inside that you sent back for processing. (The newspaper editor receiving the demo was rather dubious that the product would ever catch on!) Anyway, my point is that there was no Kodak and although there were small vendors of materials it was an enthusiast market and they all made their own stuff. There was an atmosphere of experimentation and sharing as they each found the next great thing. It was all incredibly "high-tech" stuff. But also, the amatuer enthusiasts could be, and were, just about as deep into it as the corporate giants (such as they were) of the time. And, you might be surprised at how little the technology has changed since that time, other than the major leaps like panchromatic dyes. It's amazing what those guys knew!

In a post-Kodak world, should that come to pass - and maybe even if it doesn't, I believe we analog folks will come full circle and pick up much where these guys left off when Kodak, Agfa and Ilford seriously entered the picture and it became much more practical to buy economical well made materials than to try to understand and make them your self.

The big difference for us being that we know what's possible because it has already been done. But unless the treasure trove knowledge vaults of Eastman Kodak are suddenly spilled open, we will have to follow the bread crumbs and re-discover it all. So. it's you filling in a developer here, me figuring out how to coat PET in another thread, Denise with an emulsion, PE sharing everything that he knows, Holmbergers up to something, and someone else creating a great new formula or method for something else that will pick up all these pieces and everyone can play a part. Maybe the world is opening up - not shutting down.

So, your developer is great stuff! Can't wait to try it!

(enough of the cathartic now)

 

[kb3lms]

To continue with the technical discussion, Mark, you mention that development times are longer for this formula than XTOL. I see above where you say the time multiplier for TMY is 2.19. Do you have a general idea where we might start with development for a given film (say HP5 or Fomapan 100) based on XTOL? Do you think 2.2 might be a good number? I'm sure it will vary somewhat for each individual film. Just looking for general guidance.

-- Jason

 

[albada]

To continue with the technical discussion, Mark, you mention that development times are longer for this formula than XTOL. I see above where you say the time multiplier for TMY is 2.19. Do you have a general idea where we might start with development for a given film (say HP5 or Fomapan 100) based on XTOL? Do you think 2.2 might be a good number? I'm sure it will vary somewhat for each individual film. Just looking for general guidance.
-- Jason

Jason, thanks for sharing the experimenters' approach and attitude. You got it right! I find that it is an adventure. It's almost like explorers of old looking for new lands: I enjoy discovering something new. Surprisingly, even after all these decades, there are still discoveries to be made in B&W developers. Anyway, the formula for this developer looks like something that was diluted 1+1, but it was actually designed that way, and is matching or even beating XTOL's image-quality.

The 2.2 is as good a guess as any for different films. The pH is lower, which films probably respond differently to, so a little dialing-in will be needed for each film.

I didn't know you were working on coating PET. Wow! Maybe I should pay attention to the other forums out there. A quick search showed the long substrates thread.

Mark Overton

 

[polyglot]

Mike and Jason: Thanks for the encouragement. My original motive for creating a concentrate was to avoid waste because we occasional shooters can't use 5 litres in 6 months. But Kodak's bankruptcy has heated the fire under me. I love XTOL, and want to be certain a proven replacement is available in case Kodak's B&W division is dismantled.

Mark Overton

I absolutely do not want to discourage you from this work, because access to a liquid-concentrate long-life XTOL would be fantastic even if it's just a recipe. But I should point out that Xtol-equivalent developers are available from Freestyle under generic brands, though I've not tried them. Personally, I just bought 15 bags of the yellow and I expect they'll last me a decade.

 

[Murray Kelly]

It is with increasing awe and wonderment at Mark's work on this project as I sit on the side, sandbagging. Thanks for all you have done, Mark.
For the chemists here I ask if oxalic acid would work as an Iron getter? Perhaps it would ruin the developing agent too? I find it easy to get tho others may have difficulty.
Murray

 

[Gerald C Koch]

No oxalic acid is a poor chelator for iron (III).

 

[albada]

I absolutely do not want to discourage you from this work, because access to a liquid-concentrate long-life XTOL would be fantastic even if it's just a recipe. But I should point out that Xtol-equivalent developers are available from Freestyle under generic brands, though I've not tried them. Personally, I just bought 15 bags of the yellow and I expect they'll last me a decade.

That's a good point about XTOL-clones already being available. I wonder how much testing they've been through?
Anyway, you might want to store those 15 bags in the freezer. I don't know what their shelf-life at room-temperature is, but it's probably under a decade.
Testing is an interesting topic. I've been thinking of the kinds of tests I'll want to run my concentrate through. These include:

• Aging in various storage-conditions (hot humid areas are probably the worst).
• Tolerance to errors in measurements by users.
• Water types: hard, soft, well, softened.
• Film types: PanF on the slow side, to Delta 1000/P3200.
• Temperatures: 18C to 28C should cover the range.
• Pulling and especially pushing.
• Dilutions, although this dev is more dilute than most so we might not want to dilute it any more.

Each test would need to be a full roll to check capacity, and compare grain/density/sharpness with XTOL.
Any other tests that should be done?

Mark Overton

 

[albada]

...some type of test in which you determine the minimum quantity of stock solution needed to develop an entire role to "D-Max"...

I had not thought of this. Maybe I could expose a whole roll by loading a reel in the light, but that would not imitate actual usage. Maybe take pictures of the light-table or northern sky to get a controlled dense exposure? Anyway, yes, minimum solution needed would be a good thing to check. I'll think more about how to do this. I suspect the dev-times will increase disproportionately (due to greater exhaustion) as the volume of solution drops, so it'll take multiple attempts (at one roll a pop) to dial-in the correct time. The result would be a few points on an exhaustion-curve, and then we would pick the cut-off point.

Mark Overton

 

[Photo Engineer]

Mark, there is a test for this using small quantities of film. It uses standard clips of 35mm film.

PE

 

[Peter Schrager]

as per the listed formuls how doesonemeasure .05 g in the real world??
thanx, Peter

 

[Peter Schrager]

that's measure .05 gram phenidone....
Peter

 

[Photo Engineer]

Peter, use a dilute solution of Phenidone and add it as needed.

PE

 

[albada]

Mark, there is a test for this using small quantities of film. It uses standard clips of 35mm film. PE

Michael wanted to determine the minimum quantity of developer required for a roll (80 square inches). Can this be determined without developing an entire roll? I guess one could develop a 20th of a roll, for example, using a 20th of the developer, by holding the strip to the bottom of the tank using magnets. But a 20th of 100 ml is only 5 ml, and I wonder if I could reliably get such a small quantity to cover the bottom of the tank. Did you have something else in mind?

Anyway, the home-made pH-tester I built a couple of weeks ago gave me time to decide what I really wanted. Here's what I got for the reasonable price of US$53 on ebay:



It's odd: That electrode cost three times as much as the meter. I don't have a temperature probe for it, so I can't use ATC -- auto temperature compensation. So my calibrations and measurements are all done at 20C.

Also, I built a (hopefully) better baffle for holding fluid steady while developing test-strips. A strip is held to the bottom of the tank with magnets, and this baffle stops unwanted fluid-movement:



The short legs you see on the bottom are just tall enough to clear the magnets.

Mark