First developed in England around 1740. The air twist was a somewhat logical evolution of the air trap, a technique exhibited in earlier glassworks of the Venetians and Bohemians. Experimentation of this technique was encouraged greatly by the Excise Act of 1745, and of course, the ever increasing customer demands for beautiful stemware.
Typically distinguished as either a single series or double series twist, triple series glasses do exist, although they are exceedingly rare. The traditional air twist is created using a pronged tool to indent the molten glass, this leaves behind air cavities that are able to be stretched twisted and entwined. The more complicated the pattern and form, generally the more skill and experience was needed to accomplish the task.
English glassblowers were trained to work the glass right-handed and away from the body, this led to the vast majority of English twisted stem glasses being rotated uniformly clockwise.
Related to the air twist is a variation known as the mercury twist, revered for its mirror-like refraction, not unlike liquid mercury or quicksilver.