Traditional paraffin wax candles have a property of having a very smooth post-burn surface on the candle. This is the usual appearance of a candle that people have come to expect. In contrast, the rough, bumpy tops seen after burning a soy wax candle are caused when the hot wax in the melt pool cools and solidifies at an inconsistent rate. This is a feature of an all-natural soy wax candle giving you the assurance that you are burning a naturally-derived product. It does not affect the performance of the candle.