I read that a good way to solder flex-track to itself and turnouts, bridges, etc so it's easy to remove is to use half a joiner, loosen it, then use desoldering braid to remove the solder on the outside, then heat up the joiner so the solder that gets down inside it melts, then push it to one side or the other with a screwdriver or something.
If anyone's tried this, would 80 watts be enoughto melt the solder inside the joiner?