I use a mix ( 1part bees wax 3 parts Townsend "Brewers Pitch") for pitching mugs, tankards, Flasks.... the wax helps the viscosity and keeps it a bit more flexible in colder weather.
I started with just wax when I lived and worked in cooler places... flasks did not stay water tight in hotter places so I went with straight pitch...then that cracked when i was back up north... the blend has worked well.