In my case it means I keep buying the same Phenidone from my current sources, yes I tend to exhaust my PQ print developers whne mixed up, but I also use far less when I know a session is only a few prints.
Originally Posted by Rudeofus
I make commercial strength PQ parer developers so fairly concentratedand substitute the Sodium Carbonate with Potassium Carbonate and Hydroxide, I don't have any issues with storage and with living abroad for 7 years was often leaving part full bottles for months between intensive printing sessions when back in the UK. I should have split it into smaller bottles but it lasted.
There's posts in threads on APUG (from US members) commenting about how well their PQ developers last and how they store part used and re-use them so the US Phenidone must be similar in terms of its stability.
The Ilford Axford-Kendal Fine grain PQ developer sold as Autophen (a PQ variant of D76/ID-11) had an extremely long working life replenished, it just didn't collapse like D76/ID-11.