system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How does a candle not burn all at once?

As you know, when a candle is burning there is a pool of melted paraffin around the wick.

How is that not getting ignited? How come paraffin only burns when it's saturating the wick?
gpt
Paraffin wax only burns when it is a gas and mixes with air. To become a gas, it must first be a liquid. Liquid paraffin in bulk, like a puddle, conducts heat away from the surface too quickly to burn under normal conditions. Small flecks of it will burn, as they have more surface area compared to how quickly they lose heat through the bottom. The result is that as wax melts, the wick sucks it up. Then the fire boils it off of the wick, and it mixes with air and burns. The paraffin at the bottom, meanwhile, does not receive enough heat to boil. A little bit of it will evaporate, and may get sucked into the fire, but very minuscule amounts.