Most fragrance oils used in candles have a flashpoint between 140° F (60° C) and 200°F (93°C), so it’s best to add the fragrance oil as close to the flashpoint as possible, otherwise if too hot, it will vaporize and most of the scent will be lost, or if too cool, the oil might separate from the wax instead of binding during the cooling process. Check the product label or contact the company purchased from to inquire on the exact flashpoint.