Quote Originally Posted by piotres View Post
It's LeakLock -special compund made by Refco to seal threads in refrigeration units .
Just as well
It just looked a lot like silicon.
And anyway, leak lock is over rated. If the flare doesn't seal properly, leak lock isn't gonna seal it.
Leak lock is more for thread locking purposes to stop the nut undoing itself over time with expansion and contraction.