Introduction
Of all the stem types produced during the golden age of English drinking glass, the air twist is perhaps the most immediately captivating. Trapped within the stem, columns of air have been drawn and twisted into spirals of extraordinary delicacy — a feat of glassmaking skill that, once understood, makes the finished object all the more remarkable. Air twist glasses were produced for approximately three decades from around 1740, and in that relatively short period English glassmakers developed a vocabulary of twist configurations of remarkable variety and ingenuity. For collectors today, they represent one of the most rewarding and accessible areas of 18th-century English glass.
How Air Twists Were Made
The air twist stem is formed by a process of deliberate entrapment and manipulation of air within the molten glass. The glassmaker begins with a solid gather of glass, into which a series of indentations are made using a pointed tool — typically arranged in a pattern around the surface of the gather. When a second gather of glass is applied over the top, the indentations become sealed pockets of air trapped within the glass mass.
The glassmaker then draws out and rotates this gather, elongating it into a stem. As the glass is drawn, the air pockets are stretched into long, thin columns; as it is simultaneously rotated, those columns are twisted into spirals. The speed of drawing and the degree of rotation determine the tightness and character of the resulting twist. The process requires considerable skill and judgement — the glass must be worked at precisely the right temperature, and the drawing and rotation must be controlled with consistency to produce an even, regular twist along the full length of the stem.
The result — a stem containing one or more columns of trapped air, twisted into spirals of varying complexity — is both a technical achievement and a thing of considerable beauty.
Dating Air Twist Glasses
Air twist stems were produced from approximately 1740 to 1770, with the peak of production falling in the 1740s and 1750s. They succeeded the baluster stem as the dominant decorative form and were themselves succeeded by the opaque twist from the mid-1750s onwards — though air twists and opaque twists were produced concurrently for a period, and the two forms are sometimes found combined in mixed twist stems.
The introduction of the air twist coincides broadly with a shift toward lighter, more elegant glass forms following the 1745 Excise Act, which taxed glass by weight and encouraged glassmakers to produce thinner, lighter pieces. The air twist stem, being largely composed of air, was well suited to this new aesthetic and economic reality.
Air Twist Configurations
The variety of air twist configurations is one of the great pleasures of collecting in this area. Twists are broadly categorised as single series or double series, depending on whether one or two distinct twist elements are present within the stem.
Single Series Air Twists
A single series twist contains one configuration of air columns running the length of the stem. Common single series forms include:
- Single spiral thread — the simplest form, a single column of air twisted into a single spiral. Clean, elegant, and among the earliest air twist configurations.
- Multiple spiral threads — several fine air columns twisted together in a single spiral band. The threads may number from two to a dozen or more.
- Corkscrew — a tight, helical spiral of one or more air columns, producing a bold, clearly defined twist.
- Gauze — a fine, lace-like configuration of many very thin air threads twisted together, producing a delicate, almost textile-like appearance within the stem.
- Cable — a thick, rope-like twist of multiple air columns, giving a bold, substantial appearance.
- Spiral band — a flat, ribbon-like air inclusion twisted along the stem, broader and more band-like than a thread.
- Mercurial twist — produced from a larger air pocket than standard twists, the mercurial (or mercury) twist has a notably bright, reflective, almost silvery appearance. The larger air column catches and reflects light more dramatically than finer threads, giving the stem a distinctive brilliance. Mercury twists are among the most desirable single series configurations.
Double Series Air Twists
A double series twist combines two distinct configurations within a single stem — typically a central element surrounded by an outer spiral. The two elements twist in the same direction but at different rates, producing a complex, layered visual effect. Common double series combinations include:
- Central multi-ply spiral with outer corkscrew — the most frequently encountered double series configuration.
- Central gauze with outer spiral threads — a particularly fine and delicate combination.
- Central cable with outer spiral band — a bolder, more substantial double series form.
- Two independent corkscrews — two separate corkscrew elements running in parallel within the stem.
Double series air twists are generally considered more desirable than single series examples, reflecting the greater skill required in their production and their more complex visual effect.
Bowl and Foot Forms on Air Twist Glasses
Air twist stems are found with a wide range of bowl forms, reflecting the full vocabulary of mid-18th century English glass production. The most commonly encountered bowl forms include the round funnel, waisted funnel, ogee, double ogee, bell, and bucket. The trumpet bowl is also found, particularly on earlier examples.
Feet are typically conical, and the folded foot — common on earlier glasses — becomes less frequent on air twist glasses produced after 1745, consistent with the weight-reduction pressures of the Excise Act. A folded foot on an air twist glass is therefore a useful indicator of earlier production, likely pre-dating or immediately post-dating the Act.
Decorated Air Twist Glasses
Air twist stems are found both plain and with engraved bowl decoration. Engraved examples are considerably more valuable than plain ones, and the subject matter of the engraving adds further layers of interest and value.
- Jacobite engraving — air twist glasses with Jacobite symbols (rose, buds, star, oakleaf, Latin mottoes) are among the most sought-after pieces in English glass collecting. See our guide to Jacobite Glasses for full detail on symbols and authentication.
- Masonic engraving — Masonic symbols on air twist glasses are found, though less commonly than on firing glasses.
- Fruiting vine — a popular decorative motif, particularly on ale glasses, where hops and barley are also found.
- Floral and foliate decoration — roses, tulips, and other flowers appear on many engraved air twist glasses.
- Armorial engraving — coats of arms and crests, engraved to commission, are found on finer examples.
What Affects Value
Within the air twist category, value is determined by a combination of factors:
- Twist complexity — double series twists command premiums over single series; mercury twists and gauze twists are particularly desirable within the single series category.
- Bowl form — less common bowl forms (double ogee, pan-topped, thistle) are more desirable than the ubiquitous round funnel.
- Engraving — Jacobite engraving adds the greatest premium; other period engraving also adds value relative to plain examples.
- Foot type — a folded foot, indicating earlier production, adds desirability.
- Condition — chips to the rim or foot significantly reduce value; examine carefully under good light.
- Size — unusually large or unusually small examples attract collector interest.
- Colour — the vast majority of air twist glasses are in clear lead glass. Coloured examples — green, blue, or amethyst — are extremely rare and command very significant premiums.
Building an Air Twist Collection
Air twist glasses offer an ideal combination of accessibility and depth for the collector. Plain single series examples in good condition can be acquired at modest prices, providing an excellent entry point. As familiarity with the form develops, the collector can pursue finer double series twists, engraved examples, and rarer bowl forms with increasing confidence.
A focused collection might explore the full range of single series configurations — assembling one example of each major twist type — before moving to double series. Alternatively, a collection built around a single bowl form in different twist configurations, or a single twist type in different bowl forms, provides a coherent and visually satisfying display.
Whatever the approach, the air twist stem rewards close attention. Hold a good example up to the light, rotate it slowly, and watch the columns of trapped air catch and release the light as the twist turns. It is one of the quiet pleasures of antique glass collecting — and a reminder that the best objects repay the time spent looking at them.
The Wonder Room occasionally offers fine air twist stem drinking glasses of the 18th century. Browse our current collection or explore further guides in Collector's Insights.