No waste the candle / candle

The candle melting point increases gradually from inside to outside,
when combustion, internal melt first, external still not, internal sag ,
external melting point is high, it can better protect the internal liquid
not overflow, sufficient combustion, after the internal combustion flame temperature outer flame is highest, the candles outside also reaches melting point, followed slowly melting, this candle keeps
concave, convex outside of the state, make the candle liquid won't overflow, sufficient combustion, increase the burning time, candle will burn down completely