Do you know that candles have a memory? Once you light a candle you must allow the candle to burn all the way to the edges of the jar. Especially, for the first burn before extinguishing the flame. If not, on the next burn, the wax will only melt to the width of where it was on the previous burn cycle. This is called the candle memory.
The rule of thumb is to burn your candle 1 hour for every diameter inch of the candle jar. For example, our 12 oz candle jars measure approximately 2.75" across. So, we recommend that you burn this candle for minimum of 3 hours until you achieve a full melt pool from all candle edges. This will help prevent tunneling caused by memory issues.