[quote="Jorge Oliveira"]Or a dead developer.
That has happened with Xtol (and with a crazy mix I made...) - sudden death.

I have heard of this happening with Xtol. And when it happens you apparently have no clue because there is no discoloration of the developer.

Pyrocat-HD (and PMK) are not subject to this kind of sudden death. Whe Pyrocat-HD goes bad the clear Stock A solution turns dark brown (Stock B has an indefinite life). This has only happened to me once and when it did the developer was over 2.5 years old and was being stored in a 250ml bottle that was less than 1/2 full. In fact, it was a test stock that I deliberately left just to see how long it would last.