Geology Demo - Candle Wax Demo

It was noted that when a large candle was placed on a wood stove that the wax in the lower part of candle melted. This melted wax was less dense than the solid, and in some cases rose to the top of the candle and formed flows on the candle surface. This was reminiscent of lava flows in a non-explosive volcanic eruption, so the candle was placed on a small hot plate that could produce more localized heating within the candle. As the pictures show, the melted wax breached the top surface of the candle closest to the center of the hot plate and flowed to the lowest part of the candle surface. When the candle wax cooled and hardened, the remaining liquid wax in the source hole contracted as it became more dense, producing a sort of crater or vent.

BELOW: A candle wax volcano: (LEFT) Liquid wax rising up and almost breaching the top surface of candle. (MIDDLE) The liquid wax "lava" flowing across the candle surface and pooling in a low spot. (RIGHT) When the candle wax cooled and hardened, the remaning liquid wax contracted back into the "vent".