Melt pool

The pool of liquid wax that forms around the wick as a candle burns. For a container candle the target is usually a pool that reaches the edge of the container within about two hours on the first burn.

A pool that stays small leaves wax on the wall of the jar and tunnels; a pool that overshoots means the wick is too large and the candle burns hot and fast. Wick sizing is judged on the melt pool, not on the wick number.