I used some old rtv silicone on friday, I knew it was past it's best as I had to pull a load of solid out of the cartridge to get to some liquid. Funny thingis that the stuff I got out has not hardened after three days, not even skinned over ! This was an "eversil" acetic acid smelling sealer. No real acid smell present though. Anyone come accross this before - or can explain what has happened. I always thought that this stuffs shelf life just meant how long it took to go solid in the tube. Mark.