Progress on XTOL-concentrate

[albada]

You've gotta watch those electronic scales from Amazon. I bought one a year or so ago and later found that it is exactly 1.5 grams off across the board.

If it won't calibrate as PE suggests, then that scale is defective; is it too late to return it under warranty? I have two scales from AWS (American Weigh) bought via amazon, and both work fine and agree with each other. But I'll admit that the more expensive milligram scale (.001 resolution) glitched once, creating a mystery brew that worked great but I can't reproduce.

Mark

 

[Cor]

Hi Mark,

thanks for the elaborations! Strange that your syrup coloured brown so quickly, in my experience it is a very slow process. After all it's mixed in glycol to retard oxidation, and I believe that Phenidone is still working properly despite the colour shift.

But as you say it might very well be the quality of the TAE, mine is of high purity from Fluka I believe. In my non -scientific test it behaves the same as Xtol 1:1.
Although I now mainly use it now on a a new to me film: Fomapan 100, needs some fine tuning though, contrast is too high, but this film is said to build up contrast easily anyway.

I'll will you follow your results with great interest, keep up the good work and thanks!

Best,

Cor

 

[Kirk Keyes]

Kork said noting about NaOH being difficult to dissolve. He was describing a lab technique that allowed one to prevent formation of big chunks of NaOH. Instead, by swirling, he formed a thin film of NaOH.

That's exactly it - I needed to get the NaOH into a form that I could quickly and easily dissolve it and then transfer it into a 100 mls volumetric flask. We would digest about 20 plant samples at a time so getting into solution in a timely manner was of great importance.

 

[Kirk Keyes]

Yes, that thing is going to spoil me. But I figured out a trick for getting a temperature into the meter: apply a resistance to the ATC connector using a potentiometer. That way one can simply dial-in the temp seen on the thermometer. This evening, I tried various resistors and got a table of corresponding temperatures from the meter, so now I know what kind of resistor-network to solder together. That's another electronic hack until I find a temp probe (and I like your idea of an electrode with built-in temp sensor).

Since you like playing with electronics, you should just make yourself a temp probe. You've discovered the "secret" of the ATC probe that it's simply a resistance sensor - look around for a 10K thermistor as I think that's what's used in ATC probes. You may need an additional adjustable resistor to adjust the base reading of the termistor. Check you're owner's manual as it may say.

Then search around here on APUG in the emulsion making forum - I think PE and I posted photos of ion specific electrodes that we had made. You can use the same technique to make the ATC probe. Get a length of glass tubing that's long enough to support with your pH electrode and reach the solution, and also big enough in diameter that you can slip the thermistor and wires into the end of it. Thinner glass will give quicker response time but you want it thick enough that it will be rugged enough.

Then use a torch to seal one end of the tube and fire polish the other end. After it's cooled, use a smaller tube to transfer some epoxy into the seal end of the glass tube. Then QUICKLY insert the thermistor and lead wires into the electode housing and set them into the epoxy. Then seal the open end of the glass tubing with some more epoxy.

Fit whatever connectors you need for your meter, and you're all set!

 

[albada]

<...> As pH rises, Phenidone's B+F rises.

I need to modify the above statement that I made a few weeks ago. In that posting, I made two claims: (1) that Phenidone produces higher fog than DimezoneS, and (2) that Phenidone's fog rises as pH rises. The second claim I made is false. pH does not affect Phenidone's fog-level. Further testing shows no relationship between fog and pH. The graph I posted showing a correlation must have been due to happenstance. I still see Phenidone producing a bit more fog than DimezoneS, about .02 higher typically, a small enough difference that most people will neither notice nor care.

Mark Overton

 

[albada]

Since you like playing with electronics, you should just make yourself a temp probe. You've discovered the "secret" of the ATC probe that it's simply a resistance sensor - look around for a 10K thermistor as I think that's what's used in ATC probes. You may need an additional adjustable resistor to adjust the base reading of the termistor. <...deleted details...>

I had not thought of that! Perhaps because I'm not familiar with thermistors. It appears that Beckman meters want a 30K thermistor, probably like this one:
http://www.digikey.com/product-detail/en/B57550G0303F000/495-2132-ND/739878

Beckman sells new temperature probes for US$109, but it's tempting to DIY as you described. Thanks for posting the info.

Mark

 

[Murray Kelly]

Mark, have a look at the LM35 devices from Texas and National. The output is detected on a millivolt scale on your meter and gives a direct readout in Centigrade.
Maybe it has sufficient accuracy for your needs. I cobbled one together using the wires as the detector since the input of the TO92 device is the wires themselves. You may even want to use a small piece of PCB to increase the speed of settling.

Murray

 

[Rudeofus]

Murray, while it is nice to read a voltage which is easily convertible into a temperature, one would still have to use this temperature information to somehow manually correct the pH measurement. The advantage of the thermistors seems to be that pH meters can use these directly to temperature compensate their pH readings. Kirk's post indicates that his method creates a temperature probe working just like this at a fraction of the cost of the original part.

 

[Kirk Keyes]

Yes, that's exactly right.

The LM35 is a nice device, but you want to integrate the temp probe straight into the pH meter and a simple thermistor can do that.

For future reference, check into one-wire sensors like the ones from Maxim:
http://www.maximintegrated.com/products/1-wire/
They have a one-wire temp sensor that sends digital data on the same wire that supplies it power. Hook a small computer to it like an Arduino, and you can make a data logging temp sensor. Also - companies like Maxim will send samples of these just for asking!

Also, I just got a computer that's the size of a pack of cigarettes called a Raspberry Pi - cost like $50. It runs on USB power, has a 800 MHz CPU, and uses a SD card for memory. Not sure what I'll use it for, but it runs Linux and is pretty cool on the gadget scale!

 

[albada]

Does PE or anyone else have an idea of how long a latent image lasts in hot weather? We just had a record-breaking heat-wave for a couple of days, and below are graphs of test-strips developed (1) just after exposure and just after the XTOL was mixed, and (2) 19 days later. The house has no air-conditioning, so the temperature has been 25-30 most of the time, getting a little above 30 during the heat-wave.



Does that graph look like a latent image that has deteriorated? Notice that the toe has dropped a little. I'm wondering if the latent image has faded, or if the XTOL has weakened. The XTOL was from a completely filled unopened bottle, and my own developers are also delivering lower than expected density, so I'm suspecting the film, but wanted confirmation of this based on the graphs.

Mark Overton

 

[Rudeofus]

Mark, take a look at (there was a url link here which no longer exists) ....

 

[Photo Engineer]

Mark;

Film was not designed (for the most part) to be exposed and processed. The assumption is that there will be a reasonable lag between exposure and development. This lag is on the order of a minute or so, not seconds. On the other end, the LIK is supposed to be stable for up to a year or so, and I have verified this myself. Hot weather does make it worse.

Stephen's data in the reference from Rudi shows pretty much what I have seen, only his effect is more pronounced at longer times (days). Of course I refer to Kodak film, and we always over designed Kodak film to exceed ANSI standards. I did not see a reference to the type of film used in the referenced test, but you will find that id varies quite a bit from product to product.

That said, I suspect it is LKI due to a short time in the first test and a long time in the second. You might try exposing and then waiting about 2 hours and then processing. Something like that. Or, you could make up a batch of test strips at the same time, keep them for 1 day, and then freeze all but one. Use that one as the base and then take one from the freezer and use it as your reference when you need one. Make sure you protect all film from moisture, freezer burn, and also make sure you thaw it properly before use.

PE

 

[albada]

@Rudeofus:
Wow! Thanks for the pointer to that great thread. I had no idea that the latent image decayed rapidly in the first minutes and hours after exposure.

From now on, I'll certainly wait hours, if not 1-2 days, before developing the first frame. In my graphs, the first strip was developed 30-60 minutes after exposure, which was too soon. And I've been creating developers all this time that have been pushing a mildly decayed image up to that level, and actually got good results.

Mark; Film was not designed (for the most part) to be exposed and processed. The assumption is that there will be a reasonable lag between exposure and development. This lag is on the order of a minute or so, not seconds. On the other end, the LIK is supposed to be stable for up to a year or so, and I have verified this myself. Hot weather does make it worse.
Stephen's data in the reference from Rudi shows pretty much what I have seen, only his effect is more pronounced at longer times (days). Of course I refer to Kodak film, and we always over designed Kodak film to exceed ANSI standards. I did not see a reference to the type of film used in the referenced test, but you will find that id varies quite a bit from product to product.

Do you mind if I quote you out of context as saying, "Film was not designed to be exposed and processed."? That'll make people ask, "Then what is film designed for?"

That said, I suspect it is LKI due to a short time in the first test and a long time in the second. You might try exposing and then waiting about 2 hours and then processing. Something like that. Or, you could make up a batch of test strips at the same time, keep them for 1 day, and then freeze all but one. Use that one as the base and then take one from the freezer and use it as your reference when you need one. Make sure you protect all film from moisture, freezer burn, and also make sure you thaw it properly before use. PE

I've been reluctant to refrigerate or freeze exposed film for fear of forming condensation. Do you think the 35mm cartridge could be refrigerated if I first drove some inert gas into the can to drive down the humidity? BTW, I pull each frame out of the 35mm cartridge as needed, counting 8 sprocket-holes so the cut will be on a frame-boundary. A 36-shot roll can last a while this way, so refrigeration is tempting. OTOH, I could pre-cut the frames as you describe above, but I'd need a light-free container of some kind, and condensation would still be a worry.

Thanks for these responses. They are obviously helpful.

Mark Overton

 

[Gerald C Koch]

I have a number of plastic film cans that I purchased a few years ago. I have never had any problem with condensation with film stored in them either refrigerating them or even freezing them. If refrigerated I allow 2 hours for film in them to come up to room tenperature or overnight if they are frozen.

 

[Photo Engineer]

Mark;

Pack each exposed strip in a separate plastic package, then pack all of the strip/bag combinations in one big bag and then freeze. Thus you only have to remove one to thaw. This should work. And, I agree with Jerry. There should be no problem.

PE

 

[albada]

Jerry and Ron,

I shot a new roll last night, and it's in a metal can to age a little.
Assuming I have 38 black plastic/metal film cans (from Fuji etc.), and if I can figure out how to reliably measure and cut the frames in the dark, I'll cut 'em up and freeze them.
Thanks for the idea.

BTW, do you know if the latent image can decay rapidly at some point in time? My images were consistent until the two-day heat-wave, and then they nose-dived. It's as if some threshold was crossed causing rapid decay.

Mark

 

[Photo Engineer]

Mark;

Kodak uses frozen strips sent to customers as reference control strips. A frozen image has virtually no LIK at all.

PE

 

[Gerald C Koch]

I remember reading of some exposed photographic plates that were discovered from a failed polar expedition. The plates were over 80 years old at the time of discovery yet produced usable images.

 

[albada]

I remember reading of some exposed photographic plates that were discovered from a failed polar expedition. The plates were over 80 years old at the time of discovery yet produced usable images.

Okay folks, I cut the roll into strips and froze them. Each strip is in a plastic film-can, and they're all in a metal cooking pot with a snugly fitting lid, providing two layers of shielding against light. Thanks for the ideas about this; ageing film is a variable that I don't need.

Here's an update of the baseline developer I posted a couple weeks ago. The new one litre formula:

Sodium sulfite ..................... 45 g
Sodium metaborate ............ 2.6 g
Ascorbic acid ...................... 4.5 g
Phenidone .......................... 0.05 g (I use a 2% solution of propylene glycol)

Target pH is 8.15. For TMY2: 12.25 minutes at 20C.

The only difference between this and the baseline dev of two weeks ago is metaborate went from 2.0 g to 2.6g, raising the pH to be closer to what XTOL uses. With the higher pH, there will be less risk of failure with films that dislike low pH.
Here are the curves for this developer and XTOL:



And here are crops of neg-scans:

XTOL: This dev:

The grain looks a bit finer in loupes, and the JPEG sizes are 1% smaller. But XTOL looks a hair sharper to me in those crops.

This dev is merely a stepping-stone. Things I plan to try are (1) reduce both metaborate and ascorbic acid to reduce concentration-ratio, (2) increase pH a little more to match XTOL, and (3) replace metaborate with TEA and replace Phenidone with Dimezone S to see if a concentrate based on TEA and Dimezone S will crystallize.

Mark Overton

EDIT: BTW, I didn't mean for this posting to sound closed to inputs from others. If you have any comments or ideas to try, I'd like to hear them.

 

[albada]

More questions for chemists (or those more knowledgeable about chemistry than I):

1. Will DTPA-Na5 (or pure DTPA) dissolve in an organic solvent such as propylene glycol or TEA? All the structures in DTPA-Na5 are carbon-based, so I'm guessing it will be soluble, but I'm not sure. Would you suggest a version of DTPA other than the pentasodium salt?

2. Is there any advantage of using DTPA over HEDP (aka "Dequest 2010" and "Etidronic acid")? Kodak uses DTPA heavily, but perhaps that's because it behaves better in powder form? For a concentrate, I won't care about that. Perhaps HEDP would be more effective?

I discovered that my developers that use 45 g/L of sulfite do not form a precipitate when refrigerated (unlike XTOL). That suggests a more convenient usage: Mix it one litre at a time, and store in the refrigerator (labeled clearly!). It should last three times as long in the fridge, compared with storing at room-temperature of 20C. And six times as long in the fridge compared with room-temp of 30C. But storage means the Fenton reaction with iron will be a problem, hence my interest in chelating agents.

TIA!

Mark Overton

 

[Gerald C Koch]

DTPA is soluble in organic solvents such as glycols. Kodak uses it in HC-110 which contains no water. The sodium salt is probablely not very soluble.

 

[eworkman]

I got two packs of the 5 liter yesterday from Freestyle.
I haven't really done darkwork for a year at least.
I note that packaging is new [relative, see above] and probably better.
A and B come in same size all plastic envelopes, rather than the film-on-paper of the past.
If I can keep struggling to motivation, I have some 8x10 HP5 to develop 1:2 etc in trays.
I've mixed the fix, and the materials and tools are awaiting in the sink.

 

[albada]

It's been two weeks, and I've run experiments changing the amount of ascorbic acid in the formula.

Here's an interesting observation. Pat Gainer's article here (http://unblinkingeye.com/Articles/Synergism/synergism.html) on synergism has a graph that shows density versus ascorbic acid. It levels off when the ascorbic/phenidone ratio is 80. However, his test-developer was PC-TEA which contains no sulfite. If the developer has sulfite, the graph changes a little, as should be expected. With my developer, I found that activity levels off at a ratio of about 90.

XTOL, after converting chemicals into other equivalents, has a ratio of about 100. So I tried 100 in my dev, producing this formula:

Sodium sulfite ................ 45 g
Sodium metaborate ....... 3.1 g
Ascorbic acid ................. 5 g
Phenidone ..................... 0.05 g (in a 2% solution of PG)
pH = 8.16. For TMY2: 12.25 minutes at 20C.
​

The resulting H&D curve is an excellent match with XTOL:



The grain looks identical to me in both loupes and neg-scans. The JPEG file-sizes are equal, which objectively says the grain should be the same. Here are samples:

XTOL: Test-dev:

Notice the sharpening in both along the horizontal line near the bottom. Would you say they're sharpening the same amount? You can see the fringes (Mackie lines) from sharpening even in the thumbnails.

Anyway, I wanted to post this as a way of establishing another milestone that says "here is a developer that gives results practically identical to XTOL."

My next steps are (1) mix this as a concentrate in propylene glycol, and (2) add a chelating agent that can chelate iron. That chelating agent might be useful because I noticed that this developer is dilute enough that it does not form precipitate when stored in the refrigerator (unlike XTOL). That means you can store it in the fridge and it'll last three times as long. That got me thinking: You can make more than you need, and refrigerate the rest until it's all consumed.

Comments and ideas are encouraged as always.

Mark Overton

 

[albada]

In my posting yesterday, I forgot to say that my tests show that film-speed appears to drop a little when the ascorbicAcid/Phenidone ratio goes much over 100. Here's the curve I got when the ratio was 117:



Notice that the left 2/3 of the graph is slightly thinner than XTOL, but the right 1/3 is slightly denser. This means the neg has lower speed but higher contrast than XTOL (and same grain). The differences are small, though. Below a ratio of 90, activity begins dropping noticeably. So 90-100 seems to be the ideal range. It appears that the designers of XTOL made the ratio as large as possible so it could withstand as much ascorbate-loss as possible, but not so large as to lose speed.

I've also noticed that reducing the ratio appears to boost speed. The same seems to be true of reducing sodium sulfite. I say "appears to" and "seems" because I need to run more tests to verify these statements. Crawley's FX 55 developer was designed to achieve maximum speed, and claims a 1/2 to one stop speed-boost. Its equivalent ascorbicAcid/Phenidone ratio is only 11.6, and it has only 3.7 grams of sulfite, which seem to support my observations that low ratios of these chemicals give higher speed. Once I'm done with this XTOL-concentrate project, I'd like to experiment with speed-boosting developers.

Mark Overton

 

[Rudeofus]

In my opinion the difference in speed is barely visible, you seem to have a very flat optimum here. Since you did several test runs with different dev ratios, can you tell us from your data at which ratios you saw differences which would be more than let's say 1/3 stop or 0.1 density?