Just a quick(!) question, why would a weeping soldered fitting continue
to weep at the same rate when the supply is turned off and the pressure
removed (by opening a tap) ?

Is this just a "They all do that" thing?


....

Background if interested, this is a soldered "T" in an inaccessible
place (aren't they always?) and it's currently weeping at about 1 drop
an hour. I'm worried that could worsen, possibly without further warning.

The weep is coming from a "carbuncle" on the fitting itself, I'm
guessing it's a flux residue problem.

Getting to it is not going to be easy, barely got enough access to see
it, the current preferred plan is to just run another pipe and nix the
bath tap that the other end of this one is connected to. Never use that
tap anyway (because shower) and there is a refit in the budget at some
point