The two most common types of stills are pot stills and continuous stills. Copper pot stills are used in the traditional method of distilling whisk(e)y, but they are slower compared to continuous stills, which allows a distillery to produce larger quantities at a quicker rate. Copper is used to construct stills because it can remove many of the unwanted chemical compounds that are a byproduct of the distillation process.
During distillation, the first and most volatile compounds that are produced from the process are called the foreshots. The foreshots, which have the lowest evaporation points, consist of compounds such as methanol and different ethyl esters. Following the foreshot is the middle cut; the middle cut is the purest and most sought after portion of the distilled alcohol. The last portion of the distilled spirit is the feints. Many aromas and flavor profiles in whiskies (e.g., fruits, tobacco, smoky aromas, etc.) are derived from a mixture of foreshots, feints, and the middle cut. During distillation, a distillery may combine foreshots and feints from different runs to get as much product as possible.