Why is my soy candle leaving so much wax on the sides of the container?

A soy candle burning straight down the center, creating a tunnel, was not allowed to achieve a full melt pool on it's first burn. All-natural soy wax has a memory and if a soy candle is extinguished prior to allowing a full melt pool, all subsequent melt pools will not go past the first one.

To leave the least amount of wax on the sides of the container, go for the full melt pool on the first burn. Just remember to burn the candle for a minimum of one (1) hour for every inch of it's diameter to get it. All future burns should follow the first one's path.