A newly lit candle has a “memory” on its own. If a candle isn’t burned within its recommended minimum burn time, it will not burn completely causing tunneling. When a full melt pool doesn’t happen, candle will burn through the center.
Tunneling is when a candle burn through the center leaving the side of the candle untouched. As a customer, you will feel cheated because the candle isn’t burning properly or there are wax unburned.
If a newly lit candle reached its full melt pool, meaning that the whole top is melted, then you know that it will burn completely. 4 hour is usually when the top layer of the candle is fully melted. After the first burn, you may burn candle at around 2 hr mark.
So, if you know that you’re not going to be able to burn the candle to its full potential or until the whole layer is melted then don’t light the candle. You have to melt the top wax completely.
Of course, do use precautions such as trimming the wick before lighting the wick. Make sure that it isn’t long, cut it to 1/4 inch.