I'm doing a little fiddling with new film developers. Been having some problems.
So, what color is your phenidone? Mine is a little bit orange and I don't know the vintage. What color is your catechol? I have one that is pretty white, maybe a little purple or grey, just a cast. Another bottle is grey and stinks. I haven't used either in years and will replace as soon as possible, but don't want to replace with something that is the same.
Phenidone very pale tan/red-ish (I'm colour-blind...).
Pyrocachetol: small crystals white as sugar, larger crystals (1 or 2 mm across) off-white/grey (no idea why the difference - any chemists about?!). Strong, but not unpleasant, odour.
Phenidone - pale orange, bought in 1982. From Ilford.
Metol - light tan, from 1982.
Metol - white - from 2005.
Elon (Metol) - tan - bought second hand in 1985.
Hydroquinnone - light tan, from 1982.
Pyrogallol - tan, secondhand, from about 1960, I suspect.
Pyrogallol - darker tan than the previous one, secondhand, from about 1980 I suspect.
Pyrogallol - white, 2005.
Pyrocatechol - off-white, 2005.
I don't have any catechol or (technically) phenidone; however, I do have some Dimezone S, which is a phenidone derivative that supposedly has a longer shelf life in mixed solutions. It's a pale yellow color, and is brand new.
FWIW, I've read posts from people who say they've used decades-old phenidone (in powdered form, not in solution) with no problems. For instance:
I seem to recall reading somewhere that it'll get darker with age, but still work -- but I might be thinking of something else, like ascorbic acid.
Anyhow, you might want to start with a very simple formula just to narrow down the number of chemicals that might be causing you problems. If that works, build up to whatever you really want to use. If not, swap something out (metol for phenidone, say, using ten times as much metol, of course).
The "many, many years ago" for my phenidone purchase from Ilford was 1970. As I mentioned earlier in this thread, it is still fully active. I'm looking at a 50 gram bottle of it right now and its color is beige.
If I was mixing stock solutions in water, Dimezone S might afford some solution longevity advantage. Since I mix my stock solutions in glycol or in triethanolamine, it offers no advantage. I have a stock solution of phenidone (5 grams/liter) mixed in Propylene Glycol that is over a year old and shows no reduction in activity.
Solid phenidone is quite stable to oxidation and should be good for years. However, it will hydrolyse in solution especially at high pH.
Developing agents should be stored in a dark location to prevent them from becoming discolored. The usual discoloration is a gray or purplish color for hydroquinone, catechol, Glycin, and Metol. Phenidone will assume a reddish tan color.
Phenidone, Metol, hydroquinone, pyrocatechol, pyrogallol, and Glycine are all light tan, and work well. I also have some Amidol which is dark grey, like cigar ashes - and also works just fine.
Yep, I'm still using a batch of Phenidone (powder) that I purchased about 15 years ago, and which has sat in my darkroom ever since, and is just fine. I've also got an unopened bottle for when I run out, which at the tiny quantities needed for my Phen/C formulas may be almost as old by the time I open it.