Fire drying is by heat from open fires set on the dirt floor of the tobacco barn after the leaves have been hanging for a period of two to six weeks. This process may be continuous or intermittent, lasting from three weeks to as long as ten weeks until the leaf is cured as desired. Barns for flue curing are small and tightly constructed, with ventilators and metal pipes called flues extending from furnaces around or under the floor of the barn. Fuels used are oil, wood, coal, or liquid petroleum gas. If oil or gas heaters are used, flues are not needed.
Heat is applied carefully with attention to the chemical and physical changes in the leaf.
Flue curing requires from four to eight days. After they are cured the leaves may be piled in bulk to condition them for a time before preparation for sale. Conditioning normally is done in moistening cellars or humidified rooms so the leaves can be han-dled without breakage. During conditioning further changes take place in the leaves. The preparation for sale usually consists of grading the tobacco and putting it in bales or packages of convenient size and weight for inspection.