Modern Rodinal Substitutes Part II

pavelt2tk0 · Oct 2, 2009

BTW, Guys going through all this posts, I also tried to mix some Rodinal.

I used this recipe:
Sol A:
water 500ml
p-aminophenol 50g
potassium metabisulfite 150g

Sol B:
water 300ml
Sodium hydroxide 100g

Sol C:
water 50ml
Potassium Bromide 5g
Sodium benzenesulfonate 0.3g

This recipe comes from Soviet Union the most known book, and states this as Foma R09 Rodinal recipe. The only difference - the formula asks for p-aminophenol hydrochloride or hydrosulfate), but looking at your discussion this is definitely the mistake. It must be the base.

The principle is almost the same as usual - slowly add Sol B into Sol A, until precipitate almost dissolved.
The add Sol C, and water to make 1l.
Sodium benzenesolfonate is used to prevent oxigen diffusion into the solution. Greatly extends it life. Has no effect on the developer.

Looks it is very similar in it's activity and properties to Agfa modern Rodinal, what is different - the color, it is very light when fresh.

Ian Grant · Oct 2, 2009

Of course pH goes up like that. But you're entirely missing the point.

Right from day one when Agfa began making Rodinal (until the major shift in 1964) the important part of manufacture of it or the substitutes was that there was just enough Hydroxide to convert the metabisulphite into Sulphite and react with the p-Aminophenol. See the 1910 "Agfa" Book & remember who wrote Agfa's German handbooks - Dr Momme Andresen, who discovered p-Aminophol and designed Rodinal. To quote "Agfa-Rodinal contains only an alkaline salt of Paramidophenol, but no excess of caustic alkali". Later when they manufactured with Potassium Sulphite the level of Hydroxide dropped substantially as would be expected due to the reactions taking place.

Whether there's a trace of excess Hydroxide in Calbe R09 or not is immaterial what's important is that the bulk of the hydroxide has reacted to form that "alkaline salt of p-Aminophenol, that itself will increase the pH.

What's certain is that the pH is significantly lower than it should be from the amount of Hydroxide in the formula.

Ian

Ian Grant · Oct 2, 2009

Yes your right it's the same basic Andresen formula, I THINK there's not enough Hydroxide though to convert all the Metabisuphite into Sulphite, I'd have to go back & find the calculations which I have somewhere. If not all the Metabisulpte is converted it'll have far better keeping properties as there will definitely be no free Hydroxide.

It's the fact that there's the Sodium benzenesulfonate is used that's interesting and needs checking out.

Ian

pavelt2tk0 said:
BTW, Guys going through all this posts, I also tried to mix some Rodinal.

I used this recipe:
Sol A:
water 500ml
p-aminophenol 50g
potassium metabisulfite 150g

Sol B:
water 300ml
Sodium hydroxide 100g

Sol C:
water 50ml
Potassium Bromide 5g
Sodium benzenesulfonate 0.3g

This recipe comes from Soviet Union the most known book, and states this as Foma R09 Rodinal recipe. The only difference - the formula asks for p-aminophenol hydrochloride or hydrosulfate), but looking at your discussion this is definitely the mistake. It must be the base.

The principle is almost the same as usual - slowly add Sol B into Sol A, until precipitate almost dissolved.
The add Sol C, and water to make 1l.
Sodium benzenesolfonate is used to prevent oxigen diffusion into the solution. Greatly extends it life. Has no effect on the developer.

Looks it is very similar in it's activity and properties to Agfa modern Rodinal, what is different - the color, it is very light when fresh.

gainer · Oct 2, 2009

Correct me if I'm wrong, but I seem to remember learning that pH=14 does not necessarilly mean that the solvent that is causing that pH is saturated. In the case of strong alkalis, pH=14 may occur far below saturation, but cannot increase as more alkali is added. An acid-base reaction may occur in a strong solution of KOH and go to completion, leaving the pH at 14, with capacity remaining for more such reactions.

What happens to pH when we add just enough KOH to an amount of paraminophenol to form the potassium paraminophenolate? It seems to me that pH>7 implies that more than enough KOH was added, but even pH=14 does not tell us how much more.

Photo Engineer · Oct 2, 2009

Ian;

What is certain is that KOH + pAPH = KpAP + HOH which is a neutralization.

But, KpAP + HOH is an equillibrium reforming KOH + pAPH which is present as K + OH. Also, if you look at the molar equivalents used above, 100 g of NaOH in this case is over 2 moles of hydroxide and less than 1 mole of pAP. Even if it were the sulfate the pAP would be overwhelmed by the caustic. The Metabisulfite contributes little to this reaction in terms of OH, merely introducing the SO3= ion.

As a result, regardless of what is said, if the pH is above 7, the solution is alkaline and contains OH ions. This is fundamental chemistry. If it were acidic, then there would be H+ ions. At 7.0, there would be equal numbers of H+ and OH-. Thats fundamentally just water. That is the only place on the pH scale where there is no excess of acid or base, and that is called neutrality.

The caustic may even be equimolar to pAP or its salt, but the equillibrium causes an excess of OH- to form in the solution and that is a chemical fact. That is why the pH is so high, due to an excess of OH-. Dr Andresen may have been in error or trying to mislead people, IDK, but his statement is certainly misleading in the face of the formulas and pH values I have seen.

PE

Photo Engineer · Oct 2, 2009

gainer said:
Correct me if I'm wrong, but I seem to remember learning that pH=14 does not necessarilly mean that the solvent that is causing that pH is saturated. In the case of strong alkalis, pH=14 may occur far below saturation, but cannot increase as more alkali is added. An acid-base reaction may occur in a strong solution of KOH and go to completion, leaving the pH at 14, with capacity remaining for more such reactions.

What happens to pH when we add just enough KOH to an amount of paraminophenol to form the potassium paraminophenolate? It seems to me that pH>7 implies that more than enough KOH was added, but even pH=14 does not tell us how much more.

Patrick;

You are quite right. It also tells us though that an alkaline solution has so many moles / liter of hydroxide ion present.

PE

Ian Grant · Oct 2, 2009

gainer said:
Correct me if I'm wrong, but I seem to remember learning that pH=14 does not necessarilly mean that the solvent that is causing that pH is saturated. In the case of strong alkalis, pH=14 may occur far below saturation, but cannot increase as more alkali is added. An acid-base reaction may occur in a strong solution of KOH and go to completion, leaving the pH at 14, with capacity remaining for more such reactions.

What happens to pH when we add just enough KOH to an amount of paraminophenol to form the potassium paraminophenolate? It seems to me that pH>7 implies that more than enough KOH was added, but even pH=14 does not tell us how much more.

Spot on Patrick, you understand what I'm getting at.

It's the fact that the "potassium paraminophenolate" in a high concentration Potassium Sulphite solution has a pH of around 11.8 and when we have excess of hydroxide as in the more modern Rodinal formula we go to pH 14

pH 14 is in fact listed as being reached by 5.6% KOH solution, the MSDS's for A&O Rodinal show the KOH is only 2.7%. But 0.5% KOH is pH 13 and the Sulphite is pH 9-10 anyway so every thing there seems as expected.

Ian

Photo Engineer · Oct 2, 2009

Ian;

When you say that Potassium Sulfite solution is alkaline, what you are really saying though is that there is an excess of OH- created when you add Potassium Sulfite to water. Again, the alkalinity comes from the equillibrium which causes OH- to break off from water and form an excess of hydroxide (or alkali) and thus, KOH is present in solutions of Potassium Sulfite.

PE

pavelt2tk0 · Oct 2, 2009

Ian Grant said:
Yes your right it's the same basic Andresen formula, I THINK there's not enough Hydroxide though to convert all the Metabisuphite into Sulphite, I'd have to go back & find the calculations which I have somewhere. If not all the Metabisulpte is converted it'll have far better keeping properties as there will definitely be no free Hydroxide.

It's the fact that there's the Sodium benzenesulfonate is used that's interesting and needs checking out.

Ian

BTW, I have no electronic pH meter, but used indicator paper, it shows pH about 11,5-12.
And the thing - I just took the bottle of original Agfa Rodinal (produced 2006-2007) - it has large (5-10mm) transparent crystals in the bottle. I tried to mix rodinal many times, but I always had only very small crystals (less than 0,5mm).... And one more thing I can't understand - if I add more NaOH, crystals will dissolve, yes, pH will reach 14, but where are the crystals, which are in Agfa's developer?

Photo Engineer · Oct 2, 2009

The crystals dissolve when more alkali is added. The pAP is a weak acid and needs a large amount of "excess" hydroxide to force the salt to dissolve by forming the Phenolate.

PE

pavelt2tk0 · Oct 2, 2009

Gone through my other books and found the one: Laubert, Photographic Formulas and Tables, year 1917, 3d edition.

There is also Rodinal Formula:
Water 100ml
Potassium metabisulfite 30g
Paramidophenol 10g
Add saturated sodium hydroxide solution until precipitate dissolves.

In the beginning of the book there are comments about chemicals:
Paramidophenol - this is p-aminophenol slat formed with HCl, so this is hydrochloride.

Ian Grant · Oct 2, 2009

I used Agfa's modern Rodinal for about 18 years and it never ever crystallised. I also used a lot of it as I was processing 120 but mainly large format negatives, that sounds like a temperature problem with Sulphite crystallising.

There should be a very very small amount of crystallisation in the old Rodinal/Rodinal substitute formulae because that's how it's supposed to be made, no excess Hydroxide so just a trace of free base crystals.

iAN

pavelt2tk0 · Oct 2, 2009

Photo Engineer said:
The crystals dissolve when more alkali is added. The pAP is a weak acid and needs a large amount of "excess" hydroxide to force the salt to dissolve by forming the Phenolate.

PE

That what I'm saying - Agfa's Rodinal has pH 14, and it does have crystals....
If I make rodinal, it has pH<12, to make pH 14, I need to add more hydroxide, right? If I do that, pAP crystals dissolves very fast.....

So, what are the crystals in Agfa's developer?

pavelt2tk0 · Oct 2, 2009

Ian Grant said:
I used Agfa's modern Rodinal for about 18 years and it never ever crystallised. I also used a lot of it as I was processing 120 but mainly large format negatives, that sounds like a temperature problem with Sulphite crystallising.

There should be a very very small amount of crystallisation in the old Rodinal/Rodinal substitute formulae because that's how it's supposed to be made, no excess Hydroxide so just a trace of free base crystals.

iAN

Strange - I had three different bottles (from different batches), and all of them had crystals.

Ian Grant · Oct 2, 2009

Again Andresen's One shot p-Aminophenol formulae from the early 1900's, you see people saying they are different Formulae, but the ratio of p-Aminophenol to Potassium Metabisulphte is the samev 1 part p-Aminophenil to 3 parts Potassium Metabisulphite with add enough Hydroxide to just dissolve all the developer.

Ian

pavelt2tk0 said:
Gone through my other books and found the one: Laubert, Photographic Formulas and Tables, year 1917, 3d edition.

There is also Rodinal Formula:
Water 100ml
Potassium metabisulfite 30g
Paramidophenol 10g
Add saturated sodium hydroxide solution until precipitate dissolves.

In the beginning of the book there are comments about chemicals:
Paramidophenol - this is p-aminophenol slat formed with HCl, so this is hydrochloride.

Ian Grant · Oct 2, 2009

pavelt2tk0 said:
Strange - I had three different bottles (from different batches), and all of them had crystals.

Possibly bad storage not by you, the Russian Importer.Distributor. It keeps so well but then the temperatures in Russia do get rather low in the Winter

Ian

Ian Grant · Oct 3, 2009

Looking at the Sodium Benzenesulfonate further it's use is given in at least 4 Fuji Patents as an anti-oxidant, alongside other examples such as Suphites or Metabisulphites themselves and Ascorbic acid. It's also used in photothermography by some US companies..

If Agfa did or do still use it then it's possible that anyone trying to analyse Rodinal might think Sodium Benzesulfonate or another similar anti-oxidant was an unidentifiable fevloping agent. Ilford patented some anti-oxidants in the 1950's presumably for use in Ilfosol originally a Phenidone/Glycin based developer, and these can also be used to form developing agents. (4-aryl-2-oxytetronimic acids).

So thanks that's useful information.

Ian

pavelt2tk0 said:
BTW, Guys going through all this posts, I also tried to mix some Rodinal.

I used this recipe:
Sol A:
water 500ml
p-aminophenol 50g
potassium metabisulfite 150g

Sol B:
water 300ml
Sodium hydroxide 100g

Sol C:
water 50ml
Potassium Bromide 5g
Sodium benzenesulfonate 0.3g

This recipe comes from Soviet Union the most known book, and states this as Foma R09 Rodinal recipe. The only difference - the formula asks for p-aminophenol hydrochloride or hydrosulfate), but looking at your discussion this is definitely the mistake. It must be the base.

The principle is almost the same as usual - slowly add Sol B into Sol A, until precipitate almost dissolved.
The add Sol C, and water to make 1l.
Sodium benzenesolfonate is used to prevent oxigen diffusion into the solution. Greatly extends it life. Has no effect on the developer.

Looks it is very similar in it's activity and properties to Agfa modern Rodinal, what is different - the color, it is very light when fresh.

gainer · Oct 3, 2009

It's not clear to me why we need the pH of the stock to be 14, or the pH of the working solution to be about 12. I wanted to see the effect of using ascorbic acid in place of sulfite as the oxygen scavenger. (You know me.) I knew from experience that ascorbate above pH 11 or so is rotten as a developer. It fogs fiercely unless a terrible amount of bromide is there. As an antioxident, it cam take up two moleclues of oxygen for each molecule. I did one of my Q&D experiments. 1 gram of p-aminophenol, 1 gram of ascorbic acid, and roughly 15 grams of K2CO3, starting with 7 (1 tsp. I actually weighed it.) in a liter, adding bits of the carbonate until the sediment dissolved. The pH was about 10.6. My pH meter reads 9.6 with saturated borax. This was a working strength solution.

The results with FP4+ were quite good, about what would be expected from Rodinal at 1+25. 9 minutes at 69F gave a full scale negative of normal contrast.

Ian Grant · Oct 3, 2009

The hike in pH seems to be mainly so Agfa could get more activity out of less developing agent cutting the cost of manufacture. This was what Edward Zimmermann and other photographers mainly German where complaining about in the past and why some prefer Calbe R09.

In Europe, (less so in the UK) Rodinal has always been main stream developer, it was one of Agfa's main film developers, I've no idea how it sold in proportion to others.

Are you saying that Ascorbic at pH 11 is the cause of the fogging ? Or is this not due to the fact that a high sulphite level's required as an anti-oxidant ?

Ian

gainer · Oct 3, 2009

Ian Grant said:
The hike in pH seems to be mainly so Agfa could get more activity out of less developing agent cutting the cost of manufacture. This was what Edward Zimmermann and other photographers mainly German where complaining about in the past and why some prefer Calbe R09.

In Europe, (less so in the UK) Rodinal has always been main stream developer, it was one of Agfa's main film developers, I've no idea how it sold in proportion to others.

Are you saying that Ascorbic at pH 11 is the cause of the fogging ? Or is this not due to the fact that a high sulphite level's required as an anti-oxidant ?

Ian

I didn't use any sulphite in my Q&D trial. I did, however, try the same amounts of p-aminophenol and ascorbic acid with KOH as alkali. Total disaster. Very dense fog. pH was much higher than with carbonate. I attribute that to the fact that although the same number of K molecules is used in each case to form the aminophenolate, a little extra carbonate does not have the same effect on pH as a little extra KOH. The ascorbic acid becomes the nearly neutral ascorbate in both cases. Thus, the pH is practically all due to the potassium aminophenolate when carbonate is used.

If ascorbic acid behaves with p-aminophenol as it is theorized to do with Metol, it will regenerate oxidized aminophenolate. By keeping the pH below the point where ascorbate is a developing agent, I should be able to increase the relative amount so as to extend the storage life of a stock solution greatly. If it is successful, it will probably be a great disappointment.

Ian Grant · Oct 3, 2009

Probably making old style Rodinal with Ascorbic might work, Sulpite & just enough KOH to convert the p-Aminophenol but no more, if it starts at pH 11.8 it may drop enough on dilution to 1+50. The sulphite itself is a powerful anti-oxidant and that's almost certainly why it's at such a high level compared to other developers.

Ian

gainer · Oct 3, 2009

You will be happy to find out that the experiment failed when I tried to bring the concentrations of p-aminophenol and ascorbic acid up to the level we're looking for in a concentrated stock. The only real difference is the substitution of about 29 grams of potassium ascorbate for 192 grams of potassium sulphite in 500 ml. What am I missing?

Ian Grant · Oct 3, 2009

Is tooooooooooo late at night

Well here in Turkey anyway

I'll look tomorrow if I'm not out doing the rounds with the Crown Graphic . . . . . . . . . . .

Ian

pavelt2tk0 · Oct 3, 2009

Ian Grant said:
Looking at the Sodium Benzenesulfonate further it's use is given in at least 4 Fuji Patents as an anti-oxidant, alongside other examples such as Suphites or Metabisulphites themselves and Ascorbic acid. It's also used in photothermography by some US companies..

If Agfa did or do still use it then it's possible that anyone trying to analyse Rodinal might think Sodium Benzesulfonate or another similar anti-oxidant was an unidentifiable fevloping agent. Ilford patented some anti-oxidants in the 1950's presumably for use in Ilfosol originally a Phenidone/Glycin based developer, and these can also be used to form developing agents. (4-aryl-2-oxytetronimic acids).

So thanks that's useful information.

Ian

I'm not sure that sodium benzenesolfonate came from Agfa - the book states it was proposed by one of russian scientists as an agent preventing oxigen diffusion into the stock solution of Rodinal. It was stressed about diffusion, but not oxidation. And for me this makes the point - if there is no diffusion, there is no oxidation. But from practice it is also an anti-oxidant.

I mixed two batches with benzenesolfonate and without and there is huge difference:
1. First batch was without it, and when I got right NaOH content, I've added water to make 1 liter. It was light in color before water, and became much darken when I added. Obviously, water contained a lot of oxigen, which oxidized pAP, and I had color change.
2. Second batch - I added benzensulfonate, and after adding the water to make 1 liter, there is no color change.
One of my friends told me that he noted shelf life difference for rodinal made with benzenesolfonate and without from his previuos experience.

Ian Grant · Oct 4, 2009

Thanks for that clarification. You seemed to imply it came from Foma 's R09 formula before. Agfa/Bayer actually manufacture the chemical and it has other uses, but it's significant that Fuji use it as an anti-oxidant in one of their Instant film patents.

It makes sense to use an anti-oxidant, the problem is the high pH makes choice more difficult.

Ian

Modern Rodinal Substitutes Part II

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