Phenidone / Ascorbic Acid developers : E-72 and PC-TEA

[measwel]

The why

I have been experimenting lately with phenidone / vitamin C developers. E-72 for paper and PC-TEA for film. Both have a very similar compostion, just the solvent is different. In both cases I had failures, so I'd like to share some experience which might help someone walk the same path. To success. Not failure.

The main problem is shallow blacks and lack of contrast. Basically a lack of activity of the developer. In my experience, the culprits are in decreasing order of likelihood:

1. Too high PH = too little sodium carbonate.
2. Too little vitamine C.
3. Dead phenidone.

If you make your stock solution without the sodium carbonate - as you should to have a long shelf life - then the working solution will be too acidic to even start working.

The howto

1) Make the working solution. 1 : 3 with standard stock or 1 : 9 with tripple strength stock. Start by adding sodium carbonate to your working solution. This applies only to E-72. PC-TEA does not use carbonate. Start with 2.5 tablespoons (38 g) per litre of working solution. That should be just about right. If you can measure PH it should be around 11. Put a test paper strip in. If the blacks are not satisfying, take out 100 ml of your working solution for further testing. Add carbonate in 1 gram increments. Test until there is no change. If the blacks are still not ink deep, it could be the phenidone / vitamin C ratio.

2) The ratio of phenidone to vitamin C should be about 1 : 50 in weight. The ratio of vitamin C to carbonate should be about 1 : 4 in weight. Either too little or too much vitamin C can make the developer inactive. Too little is the more likely case, as the vitamin C oxidizes and gets used up. Too much is unlikely, as vitamin C is shelf stable and you weight it out in the stock solution. Unless you phenidone is dead. To test, take 100 of your working solution which already has the carbonate added (PH is 11). Start adding 1 g of vitamin C and 4 g of carbonate. If things improve, then you had too little active vitamin C in the solution. If the blacks are still greys... Then it is time to look at the phenidone.

3) Phenidone is quite stable on the shelf, but it can degrade if exposed to air and heat. To keep the phenidone active almost indefinitely, make a 2% solution in glycol. See the recipies below. If nothing of the above helps to bring the developer to live, definitely try a fresh batch of phenidone.

The disclaimer

I am no darkroom chemistry expert. But I did do my best to verify all stated amounts. And present what seems a sensible approach, given my level of knowledge. May someone notice an error, gladly correct me. And... I did manage to make said developers produce super deep blacks. Do not give up on them. They are great stuff.

The recipies

2% PHENIDONE SOLUTION

2 g of phenidone dissolved in 98 ml of propylene glycol heated to 60 degrees C. Do not heat over 70 C.

E-72 PAPER DEVELOPER - Stock

Water (50°C) : 750 ml - fill to 1000 ml after dissolving chemicals
Sodium sulfite (anhydrous) : 45 g - 2 tablespoons
Phenidone : 0.3 g - 15 ml 2% solution
Ascorbic Acid (Vitamin C) : 19 g - 4.25 teaspoons
Potassium bromide : 2 g - 1 quarter teaspoon
(Optional) Pyrogallol : 5 g to 20 g - 1 to 4 teaspoons

Mix from 1 : 1 to 1 : 3 with H2O

Add to the tray shortly before use:
Sodium carbonate : 80 g (5 tablespoons) per 1 litre of stock solution - DIVIDE by the number of litres in your working solution.

E-72 PAPER DEVELOPER - Triple Strength (recommended)

Water (50°C) : 750 ml - fill to 1000 ml after dissolving chemicals
Sodium sulfite (anhydrous) : 135 g - 6 tablespoons
Phenidone : 0.9 g - 45 ml 2% solution
Ascorbic Acid (Vitamin C) : 57 g - 13 teaspoons
Potassium bromide : 6 g - 3/4 quarter teaspoon
(Optional) Pyrogallol : 15 g to 60 g - 3 to 12 teaspoons

Mix from 1 : 3 to 1 : 9 with H2O

Add to the tray shortly before use:
Sodium carbonate : 240 g (15 tablespoons) per 1 litre of triple strength stock solution - DIVIDE by the number of litres in your working solution.

PC-TEA FILM DEVELOPER

Triethanolamine : 75 ml - fill to 100 ml after dissolving chemicals
Ascorbic Acid (Vitamin C) : 9 g
Phenidone : 0.25 g
Potassium Bromide : 0.2 g

Mix 1:50 with H2O (dev times for D-76 / PC-TEA)

Postscriptum

Notice the optional pyrogallol. If nothing else helps and you have some laying around, add it. It will make the shadows go pitch black on the double. You might also like the effect it has on the tone, grain and accutance. The effect will vary with the concentration you choose. Most seem to advice about 10 g in one litre of working solution. But it will not be the original recipe any more. Pyrogallol, unlike the other ingredients, has significant toxicity. If you use it, wear gloves and use tongs. Which you should do anyway.

 

[relistan]

@measwel Apologies, but it's not at all clear what you are looking for in this thread? Help with your negatives? Helping mixing things properly?

In any case, posting examples of what you got that you don't like would help.

 

[measwel]

Two things. A well working E-72 developer for myself. And some sharing of my experiences with those who may be interested. The problem is, that I had many failed attempts and thought I document my findings how the E-72 developer can be "fixed" if its not working. Regrettably, since I wrote the initial post, I learned more. The hard way. I know now, that it is not a good idea to make the tripple strength stock. Something precipitated out of the last batch I made and it became useless. Furthermore, I suspect that I may have a problem with the dissolved vitamine C and or the dissolved phenidone. So my latest approach is to make a standard strength stock solution without the active ingredients. And add the Vitamin C and phenidone just before using.

I also made a mistake regarding the sodium carbonate. 77 grams is needed, which is about 9 tablespoons, not 5. Sorry for that.

The "formula" I am using currently is:

E-72 PAPER DEVELOPER - Stock

Water (50°C) : 750 ml - fill to 1000 ml after dissolving the chemicals
Sodium sulfite (anhydrous) : 45 g - 2 tablespoons
Potassium bromide : 2 g - 1 quarter teaspoon
Sodium carbonate : 77 g (9 tablespoons)

Mix 1 : 3 with H2O

Add shortly before use:
Phenidone : 0.3 g - 15 ml of 2% solution
Ascorbic Acid (Vitamin C) : 19 g - 4.25 teaspoons

I don't know yet how well this will work. Once I do, I will write a short update.

 

[bluechromis]

I see Relistan's PC-512 as an improved PC-TEA type developer with finer grain, less fog and greater film speed. It does require part A and part B solutions, but I don't find that to be a significant inconvenience.

 

[bluechromis]

I don't quite get the concern about lack of activity and contrast with PC-TEA. It was suggested that an overly high pH might be a problem. Does not increasing pH increase activity? Is that not why alkaline materials are referred to as accelerators? I have not seen a lack of contrast with PC-TEA. I have had phenidone go bad. Increased development with PC-TEA does not result in adequate density?

 

[BHuij]

I standardized around E-72 as my only paper developer in the darkroom a couple of years ago, and have probably gone through several gallons of it since then.

My answer to the stock solutions going bad is that I don't use them. I keep pre-measured quantities of all dry ingredients in a 3D printed capsule, with alkali and non-alkali separated. I dump it into a liter of water and shake it up in the bottle for 30 seconds or so at the start of my darkroom session. That gives me an immediately useful working-strength solution.

If I am going to print again in the next couple of days, I can put it back in the bottle. It will keep for that long without any noticeable degradation in performance. But if I'm not going to use it again in the same week, I'll just dump it at the end of the printing session. It's so cheap I can do that.

 

[measwel]

I see Relistan's PC-512 as an improved PC-TEA type developer with finer grain, less fog and greater film speed. It does require part A and part B solutions, but I don't find that to be a significant inconvenience.

Thank you for the suggestion, I might try it out. After my failure to get my PC-TEA to be active, I kind of gave up and bought some HC-110 as an alternative with comparably long shelf life. Shelf life is important to me.

 

[measwel]

I don't quite get the concern about lack of activity and contrast with PC-TEA. It was suggested that an overly high pH might be a problem. Does not increasing pH increase activity? Is that not why alkaline materials are referred to as accelerators? I have not seen a lack of contrast with PC-TEA. I have had phenidone go bad. Increased development with PC-TEA does not result in adequate density?

I cut up a 35 film into pieces and spent the entire night trying to get a piece develop nicely in my home made PC-TEA. The negatives came out faded and flat - obviously a lack of activity. After each failure I tried different dillutions, adding some ingredient, all to no avail. Really not sure what I did wrong. I put the PC-TEA aside, bought some HC-110 (original formula) and turned to E-72 to make that work. My initial attemps with E-72 were failures too.

I seem to be a really bad chemist

 

[BHuij]

Almost makes me wonder if you have an ingredient problem. When I first got started with phenidone developers (Instant Mytol, which I still use all the time), I was too impatient to wait for my propylene glycol to arrive in the mail, so I mixed up a phenidone solution with some old 99% isopropyl alcohol I had lying around. It worked for a day, but the next day the phenidone had oxidized and died. Cost me a roll, and kicked off my habit of doing obsessive clip tests every single time I mix up a cup of developer to do a roll or two. I assume the alcohol was less than the 99% on the bottle indicated.

 

[measwel]

I standardized around E-72 as my only paper developer in the darkroom a couple of years ago, and have probably gone through several gallons of it since then.

My answer to the stock solutions going bad is that I don't use them. I keep pre-measured quantities of all dry ingredients in a 3D printed capsule, with alkali and non-alkali separated. I dump it into a liter of water and shake it up in the bottle for 30 seconds or so at the start of my darkroom session. That gives me an immediately useful working-strength solution.

If I am going to print again in the next couple of days, I can put it back in the bottle. It will keep for that long without any noticeable degradation in performance. But if I'm not going to use it again in the same week, I'll just dump it at the end of the printing session. It's so cheap I can do that.

Yes, that is a great approach, although it does take some time to premix and fill each capsule I imagine. One also needs the capsules. I have seen 3D models of them online. But one would have to figure out how to get them printed if one does not have a 3D printer. I actually considered doing this, but finally settled on my current solution. I premix the standard stock solution with everything except the phenidone and ascorbic acid. As it contains just the bromide, sulfite and cabonate, it should keep almost indefinitely. I take 250 ml of it, add 750 ml water and then add 15 ml of 2% phenidone in glycol and a teaspoon of ascorbic acid. Could not be simpler.

Yesterday I did not know if this approach would actually work, but today is today. I was up all night Tired but happy, if you wonder. I made the soup as described above and threw in a test paper. It turned black, but I was still weary. Since I had a case when E-72 was doing fine in the beginning but for some reason died on me halfway through the session, I added 1 ml of the HC-110 concentrate just to be sure. I had to print my photos, so I was taking no chances. I read that HC-110 can be a good paper developer, as long as the PH is right and E-72 has the right PH. 1 ml is just 1 : 1000 in the soup and the cost of this addition is low. I am not even sure it did anything, but it gave me some peace of mind that the developer would hold. And it did. This is the second day after making many small and large format prints and it is still going strong. I will probably put it in a bottle for a next session. Next time, I might not add the HC-110. But if for some reason the E-72 stock goes bad on me again, it is good to know there is this option.

My prints are drying currently. I will post a few scans how they turned out. I am very pleased with the results.

 

[measwel]

Almost makes me wonder if you have an ingredient problem. When I first got started with phenidone developers (Instant Mytol, which I still use all the time), I was too impatient to wait for my propylene glycol to arrive in the mail, so I mixed up a phenidone solution with some old 99% isopropyl alcohol I had lying around. It worked for a day, but the next day the phenidone had oxidized and died. Cost me a roll, and kicked off my habit of doing obsessive clip tests every single time I mix up a cup of developer to do a roll or two. I assume the alcohol was less than the 99% on the bottle indicated.

Yes, that is a good hint. The developer which died on me had a dark brown color. Very dark, like old coffee. I guess I had a major oxidation problem for some reason. I may have screwed up the chemistry. The soup I used today is still clear almost like water after many prints going through it.

 

[BHuij]

If your current approach is working well for you, then great!

If at any point you decide you want to try the capsules for dry ingredients, LMK. I designed and printed my own and could easily print a few for you and send them your way. I keep 6 of them in the darkroom and fill them all up at the same time when I run out (which does take ~20 minutes or so to refill 6 capsules). Kind of a pain but even when I'm doing a lot of printing, I only have to refill them every couple of months or so.

 

[BHuij]

Yes, that is a good hint. The developer which died on me had a dark brown color. Very dark, like old coffee. I guess I had a major oxidation problem for some reason. I may have screwed up the chemistry. The soup I used today is still clear almost like water after many prints going through it.

Yeah, phenidone should be light straw color in its powder form, and it does darken when it oxidizes. The stuff that went bad on me in the alcohol solution was quite literally black. Now I keep it in propylene glycol at a 2.5% strength, it seems to last at least upwards of a year (probably more), and the solution stays a pretty pale tan color. If it's dark, phenidone oxidation is the first thing I'd suspect.

 

[measwel]

Here are my results.

If your current approach is working well for you, then great!

If at any point you decide you want to try the capsules for dry ingredients, LMK. I designed and printed my own and could easily print a few for you and send them your way. I keep 6 of them in the darkroom and fill them all up at the same time when I run out (which does take ~20 minutes or so to refill 6 capsules). Kind of a pain but even when I'm doing a lot of printing, I only have to refill them every couple of months or so.

That is a kind offer. Thank you. Let me try my current approach for some time and if it doesn't work out, I will message you. In any case, I appreciate your kindness.

PS Have you seen my darkroom control application?

Darkroom control program

Hi, My light meter based timer broke down and I got angry. Timers cost a bit and do not offer all the functions that I would want. Since I was controlling my lights with a smartlife app on my phone, I wondered if I could do it with a PC. Then I wondered if the smart leds would be darkroom safe...

www.photrio.com

I am using it as I do not have a darkroom timer and it works great for me.

 

[BHuij]

Here are my results.


That is a kind offer. Thank you. Let me try my current approach for some time and if it doesn't work out, I will message you. In any case, I appreciate your kindness.

PS Have you seen my darkroom control application?

Darkroom control program

Hi, My light meter based timer broke down and I got angry. Timers cost a bit and do not offer all the functions that I would want. Since I was controlling my lights with a smartlife app on my phone, I wondered if I could do it with a PC. Then I wondered if the smart leds would be darkroom safe...

www.photrio.com

I am using it as I do not have a darkroom timer and it works great for me.

Read through that thread. Looks very cool! I have often caught myself just shy of going down the rabbit hole that is getting accurate print times without test strips, using some kind of metering system.

For the time being, I am using a custom built LED head in my Beseler 45MXT. I uses a 16x16 neopixel array, a diffuser panel cannibalized from an old Zone VI cold light, a custom PCB, a Pico with RP2040 MCU to run the circuitpython script, and honestly it works beautifully. I can change from grade 00 to grade 5 by changing the relative blue and green pixel values, I can dial in up to 5 stops of effective "neutral density" for when I'm making smaller prints or want more time to dodge/burn, and the controller I built for it lets me adjust timing in seconds, minutes, stops, or 1/12 stops.

 

[measwel]

Read through that thread. Looks very cool! I have often caught myself just shy of going down the rabbit hole that is getting accurate print times without test strips, using some kind of metering system.

For the time being, I am using a custom built LED head in my Beseler 45MXT. I uses a 16x16 neopixel array, a diffuser panel cannibalized from an old Zone VI cold light, a custom PCB, a Pico with RP2040 MCU to run the circuitpython script, and honestly it works beautifully. I can change from grade 00 to grade 5 by changing the relative blue and green pixel values, I can dial in up to 5 stops of effective "neutral density" for when I'm making smaller prints or want more time to dodge/burn, and the controller I built for it lets me adjust timing in seconds, minutes, stops, or 1/12 stops.

That's great! I got used to the good 'ol ilford filters and since I usually end up around 2.5 anyway, I can live with the workflow. Setting the contrast and light intensity from the PC would be something else though. I had a smart led in my durst m601, which I could control from the darkroom app, but it was not bright enough.

As for the metering... yeah, I wanted to measure the light hitting the beazel and adjust the timing for a given paper automatically when enlarging. But the only light sensor that is also a smartdevice that I found isn't sensitive enough. It is a daytime meter. I get readings around 0 lumen at larger enlargements, even with fully open lens. We would need a relatively sensitive light sensor, that would be readable from python. Knowing my paper, I more or less know what base time to set. It is always the same, as I normally open or close down the lens to get a similar brightness on the beazel, regardless of the enlargement. If the brightness looks about right, I know the base time will be X. But it would be much better if it could be set automatically by the program by taking a light reading. Then I could leave the lens at the optimal apperture and have more flexibility in the timing.

Even if we were able to calculate the print time accurately, we would probably still want to make a teststrip, especially of the part of the image that interests us most.

Speaking of teststrips, I plan to build a teststrip jig that would allow me to easily test the same part of the image at different time in 1/3 stops increments. There is a 3D design online, but it is not the best. https://www.thingiverse.com/thing:4923248

If you have a 3D printer, maybe we could have a go at it and make something better? For one, the tray should be larger to allow 7 strips - a full stop in each direction. And it should have magets in the sides, so the next strip position clicks in place when you slide it. It should also have some smart way to hold the paper down, again with magnets probably. Sticking it down with bluetack isn't good. The length of the paper should be standardized (8 inches seems good for 7 strips), but it would be nice to have some flexibility regarding the width. As I might just cut off a strip from say an 8x10 and don't wanna be very precise about the width then.

 

[measwel]

Here are my results using E-72. I love this kind of "Jim Jarmusch Dead Man" aesthetics. Brilliant highlights, deep blacks, subtle tonality, leaning towards high-key.
For the record; shot on 120 fomapan 100@100 with an old Zeiss Nettar. Speaking of which; I love that old camera. Fully manual, no light meter, no focus,, no autowinding, the lens needs tons of light... But the wonderful thing about it is, that the lens folds and it fits in your back pocket. So you can pull it out at any time and have a 120 6x6 ready to shoot. Despite it's age, I still love the pictures it takes.

Take a look.

The scans were made with a normal flatbad scanner from a relatively small print. In real life the prints are very sharp.

 

[BHuij]

Speaking of teststrips, I plan to build a teststrip jig that would allow me to easily test the same part of the image at different time in 1/3 stops increments. There is a 3D design online, but it is not the best. https://www.thingiverse.com/thing:4923248

If you have a 3D printer, maybe we could have a go at it and make something better? For one, the tray should be larger to allow 7 strips - a full stop in each direction. And it should have magets in the sides, so the next strip position clicks in place when you slide it. It should also have some smart way to hold the paper down, again with magnets probably. Sticking it down with bluetack isn't good. The length of the paper should be standardized (8 inches seems good for 7 strips), but it would be nice to have some flexibility regarding the width. As I might just cut off a strip from say an 8x10 and don't wanna be very precise about the width then.

That test strip maker is my design I'm pretty happy with it after using it for a few years. I did make a "final" version that comes in two sizes, but I've moved away from Thingiverse and onto Printables. Link to the newer one here.

It does automatically align the strips with the opening using magnets in the sides that "click" it into place (as did the old version you linked). For the new one, I found on my non-magnetized baseboard that regular old silicone cupboard bumpers work just great to keep it in place without sliding around. To be clear there are basically two "parts" to the design - the base, which I used to stick down with poster tack, and the "carriage" which actually holds the paper. The carriage slides through the base to expose different areas of the paper to the opening. The carriage holds the paper without needing any poster tack. You just slide the paper in.

You're not the first person to suggest a version that can do more exposures than 3 or 4. I haven't personally found the need for that, but the files should be relatively straightforward to modify if you want a "longer" one and know your way around Fusion360 reasonably well. If you're happy with the paper size but want more exposures on the paper, you could realistically do pretty minimal modifications - change the size of the opening through which the paper shows during exposure, and modify the placement of the magnets to line up properly with whatever new strip size you like on the paper.

I have stuck papers into it that are smaller than the "correct" nominal size (1/4 or 1/8 of an 8x10 sheet depending on which version you're using). Seems to work fine as long as I'm not too energetic with advancing from one spot on the paper to the next.

Good feedback though! I'm always open to constructive criticism on what would make it better.

 

[measwel]

LOL. Sorry for suggesting to improve your own design And sorry about those magnets. I missed that. I do not know Fusion, but I will have a look what I can do. Thank you for posting those designs.

 

[BHuij]

No harm done