Phenidone Ascorbate 2-bath developer

Alan Johnson · Oct 26, 2006

I am intending to make this 2-bath developer for use and full bottle storage life test:
Part A: Sodium Ascorbate 50g/L,Phenidone 1g/L(dissolve in 100ml isopropanol).Sodium metabisulfite 50g/L.
Part B: Sodium metaborate 12g/L
Possibly it may be a compensating developer like the Stoeckler,suitable for high subject brightness ratios.
Previously I tried the same formula without the metabisulfite but it went off after 4 months in a full sealed bottle. Possibly the Part A with metabisulfite which has a pH about 5 will last longer. 12g/L metaborate in part B is taken from Barry Thornton's formula in his book Edge of Darkness.
Any comments,improvements?Thanks.

Gerald Koch · Oct 26, 2006

Look at the formula for DS-12 as a starting point. SInce the formula section is currently down google for it.

Tom Hoskinson · Oct 26, 2006

For Part A, I would mix the Ascorbate and Phenidone in room temperature Propylene Glycol (instead of isopropanol). Metabisulfite is not needed in the A solution.

My experience shows that these propylene glycol based stock solutions will last for years.

If you need metabisulfite in the working developer, you can add it to Part B.

Alan Johnson · Oct 26, 2006

The propylene glycol or similar solvent solutions would have to be based on ascorbic acid-phenidone as sodium ascorbate does not dissolve in this solvent IIRC. Once diluted they may not keep too well , the formula I posted is intended to be reuseable like Diafine.
The P-G solution diluted is really a different developer,also not investigated,also debatable.

gainer · Oct 26, 2006

Speaking of debatable, do you have any experimental evidence that a 2-bath is any better than a highly diluted single bath used with semi-stand process and thrown away? I compared something of the sort years ago and found no significant difference in the end result. That was D-23 compared with D-23 as a 2-bath with borax second bath. It was all the rage sometime in the 70's. I couldn't find that the extra tank and time was worth the trouble. I would have been a believer if I hadn't done the comparison. I re-used D-23 without replenishment for several rolls / quart. I later made a PQ developer that lasted even longer.

Alan Johnson · Oct 26, 2006

Well Patrick, that's interesting.
A highly diluted single bath developer in this case might be something like Xtol 1+5. I have actually tried one batch of the formula I posted and the grain initially appears like Xtol 1+0.
I recon that if Xtol 1+5 was strongly compensating and fine grain we would have heard by now.

Tom Hoskinson · Oct 26, 2006

Alan Johnson said:
The propylene glycol or similar solvent solutions would have to be based on ascorbic acid-phenidone as sodium ascorbate does not dissolve in this solvent IIRC. Once diluted they may not keep too well , the formula I posted is intended to be reuseable like Diafine.
The P-G solution diluted is really a different developer,also not investigated,also debatable.

Nothing wrong with basing an A stock solution on ascorbic acid-phenidone - propylene glycol. When you add a base (the B solution) ascorbate is formed. This would result in a single session or one shot phenidone-ascorbate developer.

I am skeptical about your probability of success in formulating a Diafine-Like reuseable phenidone-ascorbate developer. Phenidone and Ascorbate have a very limited life in aqueous solutions and metabisulfite doesn't help much. You might take a hint from Suzuki's Ascorbate based developers and try adding some salycilic acid.

Alan Johnson · Oct 26, 2006

I never understood the salicylic acd additive.
I thought it was mainly to stop traces of iron in solution from catalysing the oxidation of ascorbate by oxygen fom the air. In the case of an ascorbate solution in a full sealed bottle there is no air.Does the salicylic acid serve any useful purpose then I wonder.An interesting possibility to add it though.

Tom Hoskinson · Oct 26, 2006

Alan Johnson said:
I never understood the salicylic acd additive.
I thought it was mainly to stop traces of iron in solution from catalysing the oxidation of ascorbate by oxygen fom the air. In the case of an ascorbate solution in a full sealed bottle there is no air.Does the salicylic acid serve any useful purpose then I wonder.An interesting possibility to add it though.

Alan, you can find Suzuki's take on the stability/instability of ascorbate developers here:

Dead Link Removed

Alan Johnson · Oct 26, 2006

Thanks for the link Tom.
It is however rather hard to understand and appears to refer to aerial oxidation.
I had quite a good search and both in the case of ascorbate in general and Xtol in particular there is never a straight answer given to the question:
How does the stuff decompose in absence of air?
Perhaps it is not known.

srs5694 · Oct 26, 2006

Alan Johnson said:
A highly diluted single bath developer in this case might be something like Xtol 1+5. I have actually tried one batch of the formula I posted and the grain initially appears like Xtol 1+0.
I recon that if Xtol 1+5 was strongly compensating and fine grain we would have heard by now.

You might want to compare the formula you posted to PC-Glycol, which is simpler than XTOL and more similar to yours. The usual instructions for PC-Glycol say to use it at 1+1+50 dilution. I generally use 1+1+49, which works out to 0.5g of ascorbic acid and 0.0125g of phenidone in 250ml of working solution. (I use the published variant, with 0.25g of phenidone rather than the 0.2g specified on the page I referenced.) XTOL at 1+5 also has 0.5g of ascorbic acid, but 0.0083g of Dimezone S (a phenidone variant), assuming the XTOL formula I found online based on Kodak patent information is correct. I don't know what the pH of either developer is at those dilutions, though.

Ryuji · Oct 26, 2006

When diluted, the pH of XTOL drifts upward slightly from 8.2 to 8.3 or so. This is expected of borate buffer. (My current fine grain developer doesn't do this.) However, be careful. Not many films take diluted XTOL very well.

It is hard to make developer in complete absence of air, unless you work in complete vacuum. I mix and store my chemicals in partial vacuum (2/3 of the air pressure removed... about 25cm Hg or 10 inches Hg... this is about the limit of a cheap vacuum pump). While this is more than adequate for well stabilized developers, it is insufficient for unstabilized ones.

Another problem with unstabilized developers is that, in addition to absorb dissolved oxygen, etc., during storage, they can also deteriorate very fast when the bottle is opened. Even if you make single use bottles, mixing with water, and agitation during development can be problematic. We can forget about ALL these problems with suitable means of stabilizing the developer solutions.

Alan Johnson · Oct 26, 2006

Thanks for that,Ryuji.
However, I am rather more concerned in this case with the non aerial decomposition of sodium ascorbate,which these days seems not to occur with the 5L packs of Xtol in absence of air.
Sodium ascorbate phenidone solution with no sulfite I originally tested went orange and stopped working after 4 months in a sealed full bottle. I wonder if when it has sulfite in it like Xtol that may stabilise it.

Ryuji · Oct 26, 2006

What sealed full bottle? How do you know that the solution was in absence of air?

Where did you hear that sodium ascorbate decomposes in absence of air to a significant degree? And at what condition?

I think you are chasing a wrong target.

Alan Johnson · Oct 26, 2006

It's true my result was only one but if you try a Google search for :
color shelf life neutol plus
there is a pnet thread reporting Neutol plus print developer just opened came out dark orange and later a comment that it used sodium ascorbate as its developing agent.Sorry I cannot post a link.

Ryuji · Oct 26, 2006

The reason Neutol Plus comes out orange is because of aerial oxidation. Plastic containers aren't perfect. Plus, they are not making their chemicals in vacuum, so some air gets stirred in the solution. Furthermore, once the product is sent to distribution channel and then retail store, you never know how fresh the product is.

Photo Engineer · Oct 26, 2006

I store my chemicals under nitrogen. A vacuum is less practical.

PE

Alan Johnson · Oct 26, 2006

So there are reports from others that Neutol plus goes orange and that is attributed to aerial oxidation of sodium ascorbate. Would it not be expected from this that Xtol should go orange as it also contains sodium ascorbate?Or does it contain a stabiliser and what might that be?

gainer · Oct 26, 2006

Alan Johnson said:
Thanks for the link Tom.
It is however rather hard to understand and appears to refer to aerial oxidation.
I had quite a good search and both in the case of ascorbate in general and Xtol in particular there is never a straight answer given to the question:
How does the stuff decompose in absence of air?
Perhaps it is not known.

Where do you get water without dissolved oxygen?
The mechanism by which ascorbic acid oxidizes to form dehydroascorbic acid, from what I have read, can take place in an acidic environment, so IMO you cannot depend on bisulfite to prevent it. Sulfite is not a very good preservative of ascorbates, also from what I have read. The ascorbate wants to protect the sulfite. Anything you can do to keep the ascorbic or ascorbate from ionizing will help preserve it.

The body uses dehydroascorbic acid to get past the brain-blood barrier. It has an enzyme that reconstitutes it to a form usable as a vitamin inside the brain. Maybe that's what we need in our developers as a replenisher. Beware when you buy vitamin C at the pharmacy, thinking it is either ascorbic acid or an ascorbate. I have seen some bottles that have dehydroascorbic acid on their labels.

Ryuji · Oct 26, 2006

Alan Johnson said:
So there are reports from others that Neutol plus goes orange and that is attributed to aerial oxidation of sodium ascorbate. Would it not be expected from this that Xtol should go orange as it also contains sodium ascorbate?Or does it contain a stabiliser and what might that be?

XTOL doesn't contain an effective stabilizer. But there are MANY possible reaction pathways for oxidative breakdown of ascorbates, and the major difference between Neutol Plus and XTOL is the pH. They also differ in terms of chelator they incorporate. These factors are related to what you described. You are actually looking at one of few common elements (both being ascorbate based) between the two developers, while there are several important differences.

I have several versions of modified XTOL formulae. They all contain same developing agents and sulfite at same concentrations and they are maintained at the same pH. They differ in terms of different additives. Some die fast without discoloration, some keep long and they discolor when they die, and there are all sorts of combinations. These, I'm attributing the difference to the additives.

Ryuji · Oct 26, 2006

gainer said:
Sulfite is not a very good preservative of ascorbates, also from what I have read. The ascorbate wants to protect the sulfite.

Where did you read that? In your own writing?

Alan Johnson · Oct 26, 2006

Ryuji, thank you for your clear explanations.
Patrick, my theory about non oxidative decomposition seems to have cracked up a bit,however I still have a job to account for the oxygen supply to react with the ascorbate.I have the solubility of oxygen as only 8.6mg/L at 25C, which seems small compared to 50000mg ascorbate in my formula.
I will try to get some Winchester glass bottles with glass stoppers for the tests.

Ryuji · Oct 26, 2006

The absolute solubility is largely irrelevant. It's the rate at which oxygen is consumed that matters.

Maine-iac · Oct 27, 2006

Alan Johnson said:
The propylene glycol or similar solvent solutions would have to be based on ascorbic acid-phenidone as sodium ascorbate does not dissolve in this solvent IIRC. Once diluted they may not keep too well , the formula I posted is intended to be reuseable like Diafine.
The P-G solution diluted is really a different developer,also not investigated,also debatable.

Actually, they keep just fine. I have been using a Phenidone/Ascorbic Acid/Propylene Glycol concentrate for some time, and my current batch is at least 6 months old and going strong.

I don't bother mixing the Part B up in solution ahead of time. At the time of development, I just stir the metaborate or carbonate (depending which film I'm using) into the beaker of water, then add the Part A concentrate of developing agents. This is quick, easy (I use teaspoon measurements) and very reliable and consistent in results. I have found that adding 1/8 tsp. metabisulfite per liter (also added directly to water along with the metaborate or carbonate) "gets the red out," i.e. eliminates the anti-halation layer of reddish-purple dye that is sometimes hard to get out of t-grain films.

Larry

gainer · Oct 27, 2006

Ryuji said:
Where did you read that? In your own writing?

Not mine. I don't remember whose. If I had the wherewithal to test the premise, I would leave a solution of sodium ascorbate and sodium sulfite open to air and test periodically to see which oxidized first. Personal experience, which is at best what you might call anecdotal, is that adding sulfite to a P-C developer doesn't do much to extend its tray life. Perhaps neither one preserves the other. It all depends on which is the more active antioxidant, I suppose. I do know that one molecular weight of ascorbic acid will require one mole of oxygen for complete conversion to the dehydroascorbic acid, while one mole of oxygen will oxidize 2 moles of sulfite to the sulfate.
I will see if I can find where I saw that tidbit.

I am pretty sure that the oxidation of ascorbic acid to the dehydroascorbic acid can take place in acidic solution, so that acidic pH alone is not a guarantee of long life.

Phenidone Ascorbate 2-bath developer

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