Burn 3-4 hours on your first burn, to achieve a full melt pool, this is when the wax reaches as near to the edge of the container as possible, this will avoid tunnelling.
Always ensure the wick is kept trimmed to 5mm prior to lighting. This can be achieved by trimming the wick once it is completely cooled and before the next burn. This promotes a clean, steady flame and will extend the life of your candle.
Always extinguish the candle using a snuffer rather than blowing it out to keep the wax clean and free from debris.
