Always burn your candle until the whole surface becomes liquid. This step may take a long time, especially during the first burning. When the entire top of the wax is liquid, do not burn it longer than one hour. The top layer of liquid wax should never exceed one centimeter in height. Never burn your candle more than the maximum burning time indicated in the candle’s instructions. Never burn it down totally and systematically leave one centimeter at the bottom.
For more safety rules, please check our page Art of Burning.