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Gerald C Koch
11-23-2011, 02:57 PM
I wonder what a little bit of EDTA-Na would do for stability.

As I stated before EDTA cannot be used since it actually catalyses the Fenton reaction. Don't know about NTA. This was the problem that Ryuji encountered. Which agents can be used and which cannot.

Photo Engineer
11-23-2011, 04:57 PM
Then i would suggest NTA as a replacement for Salicylic acid for a trial run.

NTA is used in Bleach iii for C41 IIRC. At least it was undergoing trials when I retired.

Thinking this over for a bit, I have to add that you need more than the constants given above. You need to know the oxidation potential of the Fe III ion when complexed and when not complexed to make a full judgment.

PE

albada
11-24-2011, 01:09 PM
Success!
The graininess and shadow-detail of the simplified DS-10 matches XTOL.
BTW, this is the first time I've ever formulated my own developer. Nothing like learning something new when you're 54 years old!

However, PE was right. pH was a surprise, and just 9g of ascorbic acid with 75g sulfite (per litre) pushed the pH lower than I thought (to 7.2). Adding a little borax didn't help enough, so I added some sodium carbonate to hit the target pH of 8.0. Here's what I ended up with:


Phenidone ............... 0.15 g
Ascorbic acid .......... 9 g
Sodium sulfite ......... 75 g
Borax ..................... 1.5 g
Sodium carbonate ... 1.5 g
Water to 1 L
Develop for 10 min at 20C/68F.


I'd like to reduce the ascorbic acid to 8 g/L (40:1 ratio with phenidone), and replace the alkalis with only borax or preferably TEA ... when it arrives in the mail in 6 days.
It would be better to measure the phenidone more accurately. It's difficult even with an electronic gram scale with 0.01g resolution.

Finally, I hope to dissolve most stuff in propylene glycol (a la PC-Glycol), yielding a developer that gives XTOL-quality at near-HC110 convenience.
This is fun. Where have I been in the last 54 years?

Comments are welcome.

Mark Overton

Alan Johnson
11-24-2011, 02:13 PM
Here is the formula of Gainer's PC Borax:

Phenidone.....................0.15g
Ascorbic Acid.................6.0g
Borax decahydrate..........19g
Water to.......................1L
pH~9
Develop for D-76 times.1L is said to process 12 rolls film.

I have used this, it works well.
It looks like you are on the way to making a somewhat similar developer but with added sulfite and lower pH to give finer grain.They usually put a little sodium metabisulfite in to make a buffer (Xtol,Mytol).
Hope you reveal your next formula.

Michael R 1974
11-24-2011, 02:23 PM
How exactly did OP evaluate the graininess, sharpness, speed and curve shapes for different contrast gradients in comparison to XTOL?

Gerald C Koch
11-24-2011, 02:33 PM
Hi Mark,

There is a principle in chemistry which can be summed up as "Like dissolves like." What this means is that in general organic chemicals dissolve most readily in organic solvents and inorganic ones in an inorganic solvent. The Phenidone and ascorbic acid will dissolve in such solvents such as propylene glycol but everything else in your formula will not. When Kodak decided to develop HC-110 which contains no water, they were forced to use some chemical tricks pH was controlled using a mixture of TEA and DEA. Since they couldn't use potassium bromide they had to use an addition product of hydrogen bromide and an amine. These chemicals are not readily available and certainly not to the home experimenter. Some are also dangerous. If you look at the threads for glycol based developers on APUG you will find that they consist of developing agents and maybe TEA. They cannot contain sulfite or bromide and so have limited flexibility.

Developing a useful developer is a very difficult task and requires a very good foundation in chemistry. The two chemists who developed Xtol worked for a year before they had a tentative formula that they could show to Kodak management. That's a lot of man-hours. For example, are you aware that for any developer with a superadditive combination of developing agents such as Xtol or D-76 that there is an optimal ratio of the two developing agents? You cannot just change the concentration of one agent willy-nilly and expect a good result.

If you wish to continue experimenting then you will need a good book on photochemistry. Grant Haist's two books are the most current but there is also Mason and Glafkides.

Good luck
Jerry

albada
11-24-2011, 07:58 PM
It looks like you are on the way to making a somewhat similar developer but with added sulfite and lower pH to give finer grain.They usually put a little sodium metabisulfite in to make a buffer (Xtol,Mytol). Hope you reveal your next formula.
Alan, thanks for the formula and the chemistry clues. I need chemistry clues because photochemistry and developer-engineering are new to me, as you'll see in my response to Gerald below. Yes, it looks like I'm heading toward a PC-Borax plus sulfite. I encourage you to try it first. :)/2



How exactly did OP evaluate the graininess, sharpness, speed and curve shapes for different contrast gradients in comparison to XTOL?

Michael, my tests are so early and preliminary that no sensitometric (sp?) measurements have been done. I simply visually compared scans from a Nikon Coolscan on the monitor, where black-point/white-point/gamma were assigned identically in the scans.



<good information clipped>
If you wish to continue experimenting then you will need a good book on photochemistry. Grant Haist's two books are the most current but there is also Mason and Glafkides.


I have these books: Film Developing Cookbook, Darkroom Cookbook, Photographic Chemistry (Eaton, too shallow), and Photographic Processing Chemistry (Mason). I would love to get a hold of Haist's set, but his books cost a few hundred dollars (I've hunted for them). I suspect they are a better investment than classic cameras. :) or maybe that should be :(
Anyway, Mason is by far the most thorough text I have, and I wish I had more information still. At your suggestion, perhaps I'll drop the $$$ into Haist's work. Which volume should I get? Well, I'm gathering many bits and pieces from the Internet. At this point, I only know some simple rules, and not even enough of them, such as the "like dissolves like" which you pointed out. My ignorance of photographic chemistry is frustrating, and I'm learning as fast as I can.

Here's an idea I thought of while in the shower: Go ahead and add insoluble chemicals to propylene glycol or TEA. They won't dissolve, so they'll be in a suspension, and will settle to the bottom of the bottle. Before measuring out some concentrate, shake the bottle to get the insolubles back into suspension. I think this can only work if (1) those solids don't cake (stick) together when settled at the bottom, and (2) the viscosity of the concentrate is reasonably low to allow quick dispersion by shaking. Any thoughts on this? Should this idea go down the shower-drain from whence it came? :)

Mark Overton

nworth
11-28-2011, 09:16 AM
I was looking at something else recently, and I was reminded that oxalic acid is another excellent sequestering agent for iron. Oxalates were used in several early developers, but DK-93 is the only one that remains well documented. IIRC, it had pretty good keeping properties, but so does the related Rodinal. Has anyone explored this with ascorbic acid developers?

P C Headland
11-30-2011, 02:23 AM
Success!
The graininess and shadow-detail of the simplified DS-10 matches XTOL.
BTW, this is the first time I've ever formulated my own developer. Nothing like learning something new when you're 54 years old!

......

I'd like to reduce the ascorbic acid to 8 g/L (40:1 ratio with phenidone), and replace the alkalis with only borax or preferably TEA ... when it arrives in the mail in 6 days.
It would be better to measure the phenidone more accurately. It's difficult even with an electronic gram scale with 0.01g resolution.

Finally, I hope to dissolve most stuff in propylene glycol (a la PC-Glycol), yielding a developer that gives XTOL-quality at near-HC110 convenience.
This is fun. Where have I been in the last 54 years?

Comments are welcome.

Mark Overton

Given you want Xtol quality with near HC110 convenience, you may want to mix up a small batch of PC-TEA. You'll have the ingredients to hand.

My admittedly limited experience led me to thinking of PC-TEA as like a cross between Xtol and Rodinal, taking the best (for me) features of each. My more experienced friend likened it to the best of Xtol and HC110.

Have fun with the experiments.

Gerald C Koch
11-30-2011, 11:33 AM
I was looking at something else recently, and I was reminded that oxalic acid is another excellent sequestering agent for iron. Oxalates were used in several early developers, but DK-93 is the only one that remains well documented. IIRC, it had pretty good keeping properties, but so does the related Rodinal. Has anyone explored this with ascorbic acid developers?

Kodak supplied the developing agent paraminophenol as the oxalate salt under the tradename kodelon. Therefore their developers would naturally use this salt rather than the hydrochloride. We should not jump to the conclusion that there is any other reason for DK-93 containing a small amount of oxalate.

Oxalic acid is a poorer chelating agent than salicylic acid. In addition we do not know whether it will inhibit oxidation or enhance it.

albada
12-01-2011, 11:40 PM
Given you want Xtol quality with near HC110 convenience, you may want to mix up a small batch of PC-TEA. You'll have the ingredients to hand.
My admittedly limited experience led me to thinking of PC-TEA as like a cross between Xtol and Rodinal, taking the best (for me) features of each. My more experienced friend likened it to the best of Xtol and HC110.
Have fun with the experiments.

Thanks for the suggestion. Coincidentally, the TEA arrived in the mail today, so you can guess what I'll be doing this weekend. :)
A few postings in apug.org have noted that PC-TEA is a little grainier than XTOL, probably due to having no solvent in the soup. Adding Sodium Sulfite creates Jordan's "Instant Mytol", described here: http://www.apug.org/forums/forum223/33880-instant-mytol.html
So I'm thinking of trying some of that Instant Mytol.

Mark Overton

albada
12-02-2011, 09:50 AM
Regarding not storing DS-10 for more than two weeks:


I think that Ryuji was being conservative at this point because he hadn't finished testing for the developer's storage life. The Stability Constant for the iron-salicylate complex is 6.55 which I think is adequate.

I found a quote by Ryuji where he says that "DS-10 is a very good fine grain film developer, but it should not be kept for more than a couple of weeks, as I've seen cases where developer went off after that period." Here's the link: http://www.apug.org/forums/forum37/19221-vitamin-c-divided-developer.html

He doesn't say under what conditions it went off. Perhaps it would last longer if kept cool and air in bottles displaced with inert gas. Gerald reports having no problems after a month.

Mark Overton

P C Headland
12-03-2011, 01:12 AM
The good thing about PC-TEA is that it seems to have keeping qualities more akin to Rodinal / HC110 than Xtol. Like Rodinal, it darkens once opened, but it's activity seems to stay the same. I'm still working my way through a batch I made almost 5 years ago.

albada
12-03-2011, 09:32 PM
The good thing about PC-TEA is that it seems to have keeping qualities more akin to Rodinal / HC110 than Xtol. Like Rodinal, it darkens once opened, but it's activity seems to stay the same. I'm still working my way through a batch I made almost 5 years ago.

PC-TEA has little developer in it, so to keep dev-times reasonable, the pH is high. But that boosts fog, and makes grain worse (compared to XTOL or DS-10). But I like the convenience of PC-TEA, and its longevity. Thanks for pointing out the nearly 5-year life you've gotten out of it. Such results are valuable knowledge. Do you know if PC-Glycol has similar longevity?

My approach will be to mix some Instant MYTOL -- organic solution, invented by Jordan and disclosed here: http://www.apug.org/forums/forum223/33880-instant-mytol.html
It has all the chemicals (except sulfite) mixed in TEA and propylene glycol. The sulfite is mixed into the working solution separately, so it's not as convenient as PC-TEA, but it's still convenient enough, and the concentrate should last years.

After testing that, I'll try changing the quantities of its developers to match DS-10, and adjust alkali to hit the DS-10 target pH of 8.0.

BTW, I tried mixing sulfite into propylene glycol as a suspension (it won't dissolve), but the sulfite granules are too large and heavy, and sink too quickly for the suspension to be of any use. Also, the sulfite sediment tends to self-glue as a single hard chunk on the bottom, so even a finely ground suspension will probably fail. That means we mix the sulfite separately. Oh well.

Mark Overton

Gerald C Koch
12-04-2011, 12:24 AM
BTW, I tried mixing sulfite into propylene glycol as a suspension (it won't dissolve), but the sulfite granules are too large and heavy, and sink too quickly for the suspension to be of any use. Also, the sulfite sediment tends to self-glue as a single hard chunk on the bottom, so even a finely ground suspension will probably fail. That means we mix the sulfite separately. Oh well.

Mark Overton

Inorganic compounds like sodium sulfite are not usually soluble in organic solvents. Kodak when formulating HC-110 (which contains no water) had to use an organic adduct of an amine and sulfur dioxide in order to get sulfite into the developer. They did the same for bromide using an adduct with hydrogen bromide.

When mixing up a concentrate with TEA or glycols be sure not to get the mixture too hot. Doing so causes some oxidation of the developing agents and results in a dark color. Actually everything will eventually dissolve at room temperature, you just have to be patient. Gentle warming can be used but the solution should never be hotter than what can be comfortably held in the hand.

Don't add any water as this negates the purpose of using a glycol or TEA. Once you add water the concentrate becomes susceptable to air oxidation. This is why HC-110 c0ntains no water and last so long. Water allows oxidation to occur.

Jerry

albada
12-04-2011, 03:59 PM
When mixing up a concentrate with TEA or glycols be sure not to get the mixture too hot. Doing so causes some oxidation of the developing agents and results in a dark color. Actually everything will eventually dissolve at room temperature, you just have to be patient. Gentle warming can be used but the solution should never be hotter than what can be comfortably held in the hand.


Jerry, thanks for the warning, and I wish I'd known that last night! I mixed some Instant Mytol, which is PC-TEA + glycol + sulfite with some proportions changed. My tests showed the pH was too high -- around 9.0 instead of 8.2. And a test-strip was dense as could be expected. I've been pondering since then what happened.

I could have goofed my measurements, but I wonder if heating destroyed some of the ascorbic acid. I heated the TEA+PG mixture in a water-bath up to simmering, so the solution was at 90-95C for around 20 minutes. The Phenidone and ascorbic acid took that long to dissolve, even with constant stirring. Do you think such prolonged heat could destroy some ascorbic acid?

What max temperature would you recommend? I notice that 50C is almost too hot to touch for me, so perhaps that would be a safe limit for these chemicals? I use 50C when dissolving Phenidone into water, but perhaps ascorbic acid is more fragile.

Do you suppose that steam from the hot water-bath could have been absorbed into the solution? An Internet-search tells me that PG is hygroscopic, so having water-saturated air around it for half an hour might have been a poor idea.

BTW, during that 20-minute stir, the solution gradually turned (and remains) a fairly strong yellow. Is PC-TEA or PC-Glycol normally yellow after mixing? Might this be due to the oxidation you warned about above?

Thanks,

Mark Overton

Gerald C Koch
12-04-2011, 04:52 PM
Hi Mark,

Ethylene and propyl glycols are hydroscopic and will readily absorb water. I would mix everything in a glass bottle to avoid this problem. Keep the bottle lossely capped. Alkalis like TEa increase the rate of oxidation of ascorbic acid. What i did was to dissolve the ascorbic acid and phenidone in the glycol and once dissolved and cool add the TEA. Using glycol would also lower the pH. I used half of the total volume as glycol and half as TEA. If the pH is too low try 40 parts glycol to 60 parts TEA. You can add a small amount of TEA to the glycol to neutraiize the acidity of the ascorbic acid to help dissolve the AA. My final solution was yellow but not a strong yellow and did not darken as much as my first attempt using a lot of heat. So keeping things as cool as possible does seem to work. I used Dimezone instead of Phenidone as it is more stable in basic solutions.

If your working developer is producing too much fog you can add some bromide. Potassium bromide will not dissolve in glycol or TEA but ammonium bromide will dissolve in TEA. This allows you to get some bromide restrainer into the concentrate. This will reduce any fog. Benzotriazole will also dissolve in the concentrate and also reduces fog. With either first find how much is needed for working strength developer to determine just how much to add to the concentrate. Years ago people would improve D-76 by adding 0.5 g/l of potassium bromide. This prevents one having to season the replenished developer. Hope all this helps.

Jerry

Photo Engineer
12-04-2011, 06:10 PM
Jerry;

Ammonium ion can cause fog in some emulsions. I would stick with Benzotriazole. Also, there is the chance that AA will dissolve more easily in TEA as you are mixing acid with base. I would be careful here though as it might not be "friendly". I have not tried this, so beware.

PE

Gerald C Koch
12-04-2011, 07:08 PM
Hi Ron,

I heated the TEA to drive off any ammonia. This was the only way short of using hydrogen bromide that I could think of for getting bromide into the concentrate. I didn't experience any fog with the amount of ammonium bromide that I was using. I originally mixed up the PC-TEA formula and did not experience any problems. But I added the AA slowly with stirring.

It was fun to see what could be done to improve the PC-TEA formula. But, getting lazy in my old age I now use HC-110 for what little developing I now do.

Jerry

Photo Engineer
12-04-2011, 07:37 PM
Very good idea. Wow, you drove off the Ammonia and effectively made the adduct! Now I think I can do that with Ammonium Sulfite. I have a pound of it. What do you think?

If it works, that is the route to all kinds of HC-110 / PC TEA takeoffs.

PE