Phenidone how can you tell if it has lost its potency?

[Vetus]

Apart from mixing a developer with phenidone in it, and trying it against fresh developer is there an easy way to tell if phenidone is still working as it should?

 

[xkaes]

I don't know, but how old is your phenidone, and what color is it?

 

[Vetus]

Don't know how old it is (ebay purchase) it is just off white.

 

[xkaes]

If it's recently purchased, especially from a reputable EBAY seller (EBAY rating over 99%), I'd try it with a short, exposed piece of a film. That will tell you if it's OK.

 

[Milpool]

Depending on the initial purity, as fresh Phenidone deteriorates it will go from white to light pink and then to tan (at which point it is useless).

 

[Ian Grant]

It keeps well, so it's unlikely to have gone off. I have some Ilford Pjenidone made in 1961, still white and fine when tested a couple of years ago.

Ian

 

[BobUK]

It keeps well, so it's unlikely to have gone off. I have some Ilford Pjenidone made in 1961, still white and fine when tested a couple of years ago.

Ian

How did you test it?

Mixed into a small test amount of a recognised developer formula. Then processing a short length of film?

Or is there a simple lab test within the limits of the average amateur darkroom mole?

 

[Ian Grant]

How did you test it?

Mixed into a small test amount of a recognised developer formula. Then processing a short length of film?

Or is there a simple lab test within the limits of the average amateur darkroom mole?

I mixed up some print developer and compared it to a larger batch with much fresher Phenidone. Not very scientific but there was no apparent difference. I bought it in 1977, the Ilford code indicates manufacture was 1961.

Oan

 

[BobUK]

Hello Ian.
I seems we need to put in a bit of effort then.
No magic test.

Thank you for that.

 

[BHuij]

Depending on the initial purity, as fresh Phenidone deteriorates it will go from white to light pink and then to tan (at which point it is useless).

I'm not sure this matches my n=1 experience. I got my phenidone powder in early 2023, and it was already a pale tan. It hasn't changed either color or effectiveness since then.

 

[Milpool]

I'm not sure this matches my n=1 experience. I got my phenidone powder in early 2023, and it was already a pale tan. It hasn't changed either color or effectiveness since then.

Like I said, it will depend on the purity of the original compound you purchased.

 

[xkaes]

I mixed up some print developer and compared it to a larger batch with much fresher Phenidone. Not very scientific but there was no apparent difference. I bought it in 1977, the Ilford code indicates manufacture was 1961.

My experience is similar to yours. I got my phenidone from Lancaster Synthesis years ago, but it's not as old as yours. I've seen people refer to phenidone as pink, but mine certainly isn't -- and I've never seen that. I would not call mine "white" or "tan" -- and the color has never changed over the years. I'd call it "egg shell", but egg shells vary. If you go to a paint store, their "egg shell" is not a "tan", it's very slightly off-white -- like a white egg.

And I've never noticed any change in usefulness -- same as Metol/Elon -- but this is just one more example of why everyone should run their own tests, because your chemicals probably won't be exactly the same as the "guy" who told you "this works for me".

 

[john_s]

Would making up a tiny batch of POTA (phenidone-only) developer give a reliable test? I did it once to test some phenidone solution in alcohol and it appeared to confirm that it was dead. But if I remember correctly I wasn't sure what to expect if it had worked to some degree.

 

[Milpool]

Would making up a tiny batch of POTA (phenidone-only) developer give a reliable test? I did it once to test some phenidone solution in alcohol and it appeared to confirm that it was dead. But if I remember correctly I wasn't sure what to expect if it had worked to some degree.

Yes, if you have a baseline. Otherwise all it’s really going to tell you is whether or not your Phenidone is alive or dead, but not a whole lot about in between. Depending on the purity decent Phenidone should be white or lightly off-white to very pale pink.

 

[Marcelo Paniagua]

Would making up a tiny batch of POTA (phenidone-only) developer give a reliable test? I did it once to test some phenidone solution in alcohol and it appeared to confirm that it was dead. But if I remember correctly I wasn't sure what to expect if it had worked to some degree.

Probably, but keeping in mind POTA reduce one full step of speed so expose accordibly.

 

[Alan Johnson]

Axford BJP 24 Feb 1956 p88-9 had a test for phenidone in fresh developers where a known volume of iodine, not more than 5% excess was added in presence of starch and back titrated with sodium thiosulfate solution.
This chem lab method can hardly qualify as an easy way.

 

[Vetus]

What is a quick easy developer formula to make in a small amount that contains phenidone? I would like to mix a small amount say 500ml and test a short length of film to see if I get any development or under developed negs.

 

[Alan Johnson]

One possibility would be PC-512 borax with the part A made up in water not glycol (no need for long keeping):

A Simple Phenidone/Vitamin C Concentrate Developer: PC-512 Borax

What follows is how I formulated a very nice developer that I have now used pretty much exclusively for the last year and a half. As it says in the title, I have called it “PC-512 Borax”. Creative name? No. But it is indicative of the formula. This nice developer is a secondary result of some...

imager.ie

If all is well with your phenidone the developing times listed in the link should give good negatives.

 

[xkaes]

What is a quick easy developer formula to make in a small amount that contains phenidone? I would like to mix a small amount say 500ml and test a short length of film to see if I get any development or under developed negs.

The problem with "a small amount" is that any formula calls for a very small amount of phenidone. I hope you have a balance that goes down to 0.00gr.

 

[Vetus]

One possibility would be PC-512 borax with the part A made up in water not glycol (no need for long keeping):

A Simple Phenidone/Vitamin C Concentrate Developer: PC-512 Borax

What follows is how I formulated a very nice developer that I have now used pretty much exclusively for the last year and a half. As it says in the title, I have called it “PC-512 Borax”. Creative name? No. But it is indicative of the formula. This nice developer is a secondary result of some...

imager.ie

If all is well with your phenidone the developing times listed in the link should give good negatives.

Thank you, that is a good option for me.

 

[Vetus]

The problem with "a small amount" is that any formula calls for a very small amount of phenidone. I hope you have a balance that goes down to 0.00gr.

I do have an electronic scale, I will make a 1% solution of phenidone in glycol. If that does not work I will try 2g in 100ml of propylene glycol.

 

[BHuij]

What is a quick easy developer formula to make in a small amount that contains phenidone? I would like to mix a small amount say 500ml and test a short length of film to see if I get any development or under developed negs.

I use my Phenidone for Instant Mytol (film developer that behaves more or less identically to XTOL), and E-72 (paper developer that behaves more or less identically to Dektol). For mixing up E-72 1 working-strength liter at a time, I can measure phenidone powder dry with my scale.

For instant Mytol, I have to make a weak solution of phenidone in propylene glycol in order to measure the tiny quantities I need for a one-shot quantity (250ml in my case) with a level of precision I'm comfortable with.

 

[xkaes]

I do have an electronic scale, I will make a 1% solution of phenidone in glycol. If that does not work I will try 2g in 100ml of propylene glycol.

My mistake. I thought you wanted to use as little phenidone as possible -- "What is a quick easy developer formula to make in a small amount that contains phenidone?"

 

[Vetus]

Mixed the pc512 developer and clip tested two short lengths of film. One length in a 1% solution of phenidone, after developing the exposed film was clear. Tried increasing the phenidone to double the amount in a fresh solution of developer. Same result. Conclusion my phenidone purchased from Poland is not fit for purpose it has now been disposed of.

 

[BHuij]

Bummer, but sure better to find out like this than losing an important roll of film.