always allow the entire surface to melt (1–2 hours depending on the size) to prevent tunneling and wick drowning
do not burn the 2 oz format for more than 2 hours — the jar may overheat
for larger sizes, limit each burn to 4 hours (ideally 2–3 hours per cycle)
recenter the wick after each use, while the wax is still soft, to help prevent the glass from cracking