Wiedermann's developers (RSC and other)

thio · Nov 16, 2017

Pink coloration is a free radical due to oxidation (but not hydrolysis) of phenidone. Acetone-based stock solution of p. is very stable (according to the Abritalin). My experiments with PG show that p. is stable in PG solution too.

Ian Grant · Nov 16, 2017

Gerald C Koch said:
At one time it was popular to add the phenidone as an aqueous solution, phenidone plus a bit of sodium sulfite to protect it from oxidation. However the solution would turn pink within a month or so. When in alcohol or chloroform solution the color change is much more rapid. One of the hydrolysis products is a red free radical. Any is free to perform this test.

As to the relative stability of phenidone and dimezone I don'tt think that it was a coincidence the Kodak chose dimezone for several of its developers HC-110 and Xtol among them.

Kodak chose Dimezones because Ilford had patents etc for Phenidone and some derivatives.

Ian

Ian Grant · Nov 16, 2017

Alan Johnson said:
My phenidone in the UK from Silverprint is labelled 1-phenyl etc, ie,it is apparently Phenidone A.

yView attachment 190276
Maybe the phenidone powder sold to hobbyists was and is Phenidone A, at least in the UK, and that which used to be in proprietary developers Phenidone B.

Well this is the same very stable Phenidone that I've bought from 3different sources over the years, that keeps well in glass and plastic bottle/containers.

Curt Jacobson, in his book "Developing" (in numerous editions) list Phenidone as being very stable both as a powder and in solution. There has been speculation that the method of synthesis can greatly affect stability, I've never and a single issue in the 40+ years I've made up my own developers with this Phenidone. Nor has anyone else that I know of.

Ian

Rudeofus · Nov 16, 2017

These Ilford patents for Phenidone (A and B) have expired a long time ago, in fact they expired decades before Xtol and the latest version of HC-110 hit the market. Given that Phenidone is quite a bit cheaper and more active than Dimezone-S, Kodak could - and would - have switched to Phenidone in a heart beat, if it was feasible. To the contrary - Ilford switched to Dimezone-S ...

About the Russian articles:

I have a large stash of Phenidone myself, years old and no signs of deterioration, so I assume Phenidone will last a long time as dry powder. Note, that Mason did not report instability of Phenidone in powder form. Open trays suffer from oxidation, whereas hydrolysis of Phenidone becomes an issue once oxidation is slowed down by good storage.
The comparison of paper developers in open trays says nothing about long term stability of Phenidone in liquid developers. BTW Metol is even worse than Phenidone in concentrated developers, because it forms a poorly soluble adduct with HQ - according to the same Mason article.
Finally, Mason describes problems with concentrated Phenidone developers rather than with working solutions, because concentrates tend to have higher pH, and their reduced susceptibility to oxidation makes hydrolysis issue even more prominent.

None of these examples refute Mason's claim.

Ian Grant · Nov 16, 2017

Rubbish ! Open trays of PQ developers last a very significant time, if you don't believe me search for people here using ID-78 over a number of days (I don't though), and decades of production of PQ liquid concentrated developers show that there's good long term stability something not possible with Metol as you say.

There may well be a limit to concentration due to pH and that limit seems to have been set at around 2.5x compared to the equivalent MQ developer (mixed stock not working dilution), so no extreme concentration. I'm basing that on ID-20 once sold as a powder develop, and the PQ version ID-62, Ilford's current PQ Universal liquid developer is approx 2x5 time as concentrated and use Potassium Carbonate and Hydroxide in place of the Sodium Carbonate. ID-78 which I use is just a very slight variation and keeps 2+ years - I make up a concentrate similar to in Ilford Patents.

Ian

thio · Nov 16, 2017

By the way Wiedermann PQ with TEA is similar to the commercial Agfa Studional. It is possible that former was "parent" of the latter.

Ian Grant · Nov 16, 2017

thio said:
By the way Wiedermann PQ with TEA is similar to the commercial Agfa Studional. It is possible that former was "parent" of the latter.

Most likely as most Eastern Block and Russian Phenidone formulae were based on Ilford or other European formulae either widely published or from patents.

Ian

Alan Johnson · Nov 17, 2017

LP Clerc, "Photography Theory and Practice" Vol 4, revised by RE Jacobson 1971 , section 582:
"Phenidone is however hydrolysed slowly by alkalies to form phenylhydrazinoproprionic acid (Quotes paper by GC Alletag 1958).
As this hydrolysis is slow it does not represent a serious objection to the use of phenidone but obviously will affect the keeping properties of developers containing it. For developers of high pH value Phenidone may be replaced by more stable derivatives such as phenidone Z or Dimezone."

Rudeofus · Nov 17, 2017

Alan, this corresponds well to what Mason wrote several years before, and none of Ian's statements refutes this one bit. Whether some companies successfully marketed aqueous developer concentrates with Phenidone B or Z may be interesting from a historical view point, but it has no relevance to the current situation of the home brewers supply market. Phenidone B/Z is gone, deal with it.

If you want a developer in liquid concentrate form, and can't get Dimezone-S for an acceptable price (doubtful, it's used in tiny amounts and Suvatlar ships world wide, Formulary ships at least within USA), then mix it in an organic solvent (TEA, PG, whatever) and provide the Sulfite separately. Aqueous concentrates mixed with Phenidone will last for a few months, but not years.

Gerald C Koch · Nov 17, 2017

I bought some Dimezone S a few years ago and the price was not high.Even though I have some phenidone I prefer to use the Dimezone.

Ian Grant · Nov 17, 2017

Rudeofus said:
Alan, this corresponds well to what Mason wrote several years before, and none of Ian's statements refutes this one bit. Whether some companies successfully marketed aqueous developer concentrates with Phenidone B or Z may be interesting from a historical view point, but it has no relevance to the current situation of the home brewers supply market. Phenidone B/Z is gone, deal with it.

If you want a developer in liquid concentrate form, and can't get Dimezone-S for an acceptable price (doubtful, it's used in tiny amounts and Suvatlar ships world wide, Formulary ships at least within USA), then mix it in an organic solvent (TEA, PG, whatever) and provide the Sulfite separately. Aqueous concentrates mixed with Phenidone will last for a few months, but not years.

Why don't you accept the realities ? You can make a liquid concentrate developer using Phenidone A that has a 2+ year shelf life. If you want proof come here to my darkroom I'll makes some up you can seal the bottle and come back and check it after 2 years and you'll find it's virtually as good as new.

You're quoting literature not real life use.

Because I spent a few years living abroad I only had rare darkroom access twice a year on visits back home to the UK and so many of my developers sat unused for months and years, I've never had a problem with my PQ developers shelf life, sure after 2+ years it's beginning to oxidise still works fine, an MQ developer with a much lower pH like D76/ID-11 lasts about a year.

I can only reiterate that in my 50+ years experience I've not seen the problems you keep harking on about with PQ developers.

Ian

Rudeofus · Nov 17, 2017

Ian, you said yourself that you were sold Phenidone Z under the name Phenidone. Can you confirm that these PQ developer concentrates with 2+ year shelf life were indeed mixed with Phenidone A, aka 1-Phenyl-3-Pyrazolidinone ?

And before you rag on scientific literature: the folks publishing these articles worked for successful commercial companies in their area of expertise, I doubt they could have published claims, which every practitioner could disprove so easily.

thio · Nov 17, 2017

Don't quarrel guys

Some posts upper I cited _quantitative_ data about stability of ID-62 with phenidone (= phenidone A = 1-phenyl-3-pyrazolidone) in a hermetically stoped jars from the russian scientific photography school. ID-62 did not change their properties for as minimum as 8 months.

Alan Johnson · Nov 17, 2017

The Film Developing Cookbook, Anchell and Troop, 1998, p24:
""The PQ developer concentrates published by Weiderman (Jacobson} are of no practical value today.
It is essential to know that Phenidone does not keep well in stock solutions, But hundreds of derivatives have been synthesised, many of which keep better in liquid, Successful commercial PQ developers use these later generation derivatives,Apparently the best is,,,,,,,,,,,,tradenamed Dimezone,"
In my case I would be looking for a concentrate to keep for longer than 8 months, insufficient data.

Alan Johnson · Nov 17, 2017

IIRC, some old Ilford research archives were donated to a University and might (or not) have more data. They may have been donated here:
https://libguides.library.dmu.ac.uk/c.php?g=295229&p=1967263
However , they are not online.

Gerald C Koch · Nov 17, 2017

I would suggest Kalogen an MQ version of Rodinal. It keeps very well and is very concentrated. I typically use it at 1+49. I have a test bottle that is over 10 years old and shows no sign of oxidation. The formula is given here.

https://www.photrio.com/forum/threads/concentrated-developers.155179/#post-2011065

Rudeofus · Nov 18, 2017

Alan Johnson said:
In my case I would be looking for a concentrate to keep for longer than 8 months, insufficient data.

Mark Overton (aka albada) posted instructions for mixing a very stable developer concentrate for a dev close to Xtol.

Alan Johnson · Nov 18, 2017

Anchell and Troop perhaps did not have room for RSC in their book, but with pH 10.4 it may be only marginally more grainy and less stable than Microphen pH 8.67-8.93.
Perhaps the advantages of having a concentrate were regarded as worthwhile.

Wiedermann's developers (RSC and other)

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