Distillation has an enormous effect on the character of spirits. After an initial mash made from grains, fruits or other materials is heated and fermented, it produces alcohol as well as various compounds known as congeners that add additional compounds. These are the less desirable or even potentially hazardous elements that are separated during distillation. Ethanol has an extremely low boiling point, so the first vapours to boil off are those containing high concentrations of less desirable congeners known as heads which must then be diverted away from spirit emerging from the condenser for disposal. Following this comes more desirable ethanol alcohol known as heart; by controlling their separation rates a distiller can control how much each component will remain in their final product.
Reflux aids copper and vapour interaction by turning vapour back into liquid form as it meets with cooler surfaces, turning back into vapour again, before falling down the still. The degree to which this occurs has an immense influence on the complexity and quality of finished spirits; taller stills with packing or “boil bulbs” at their bases promote greater reflux; similarly those equipped with an angled Swan’s Neck or Lyne Arm which points upward rather than straight down encourage this phenomenon more than others.
Mother Nature uses an effective natural cycle of evaporation, precipitation and condensation in which sunlight heats water that evaporates, clouds cool off and the resultant condensation separates according to different boiling points. Distillation replicates this natural cycle; when the vapor rises through a fractional column and cools in an enclosed chamber the components with lower boiling points (including any undesirable flavors like sulphur and acetaldehyde ) can be collected and discarded accordingly.
