Put simply, after tobacco is harvested, it is cured, then dried, and allowed to age to improve flavor. There are four common methods of curing, and the method used depends on the type of tobacco and its intended use.
Air-cured tobacco is sheltered from wind and sun in a well-ventilated chamber, where it air-dries for six to eight weeks. Air-cured tobacco is low in sugar, which gives cured leaf a light, sweet character, and high in nicotine. Wrapper-leaf and burley types are commonly air cured.
In fire curing, smoke from a low-burning fire on the barn floor permeates the leaves. This gives the leaves a distinctive smokey aroma. Fire curing takes three to ten weeks and produces a tobacco low in sugar and high in nicotine. Fire-cured types are a traditional dark-leaf class.
Flue-cured tobacco is kept in an enclosed heated area, but it is not directly exposed to smoke. This method produces bright-leaf tobacco that is high in sugar and has medium to high levels of nicotine. It is the fastest method of curing, requiring about a week. Virginia tobacco that has been flue cured is also called bright tobacco, because flue curing turns its leaves gold, orange, or yellow.
Sun-cured tobacco dries uncovered in the sun. This method is used in Turkey, Greece and other Mediterranean countries to produce oriental tobacco. Sun-cured tobacco is low in sugar and nicotine and is classed as oriental bright-leaf.
Once the tobacco is cured, workers tie it into small bundles of about 20 leaves, called hands, or use a machine to make large blocks, called bales. The hands or bales are carefully aged to improve flavor and reduce bitterness.