Taking care of your candle is important!
Before lighting your candle each time, trim your wick to 1/4 to 1/2 inch. This prevents smoking and producing a large flame which may lead to soot around the mason jar.
Each time you burn your candle, let it burn long enough to allow the melted wax on the surface to reach the edges of the jar. This may take between 1 to 3 hours depending on the size of your candle. This will allow for a clean burn without any tunnelling down the middle of the candle.
If you spill any wax, it is easy to clean up with soap and warm water.