The difference between a mouth-blown wine glass and a machine-made wine glass.

Anyone who is remotely engaged in maximising the pleasure obtained from a glass of wine, accepts that the shape, proportions, weight and aesthetic of a wine glass affects the drinker’s perception and enjoyment. The weight and aesthetic appeal to the senses in different ways, just as the size, colour or rim of a plate affect the perception of food. Yet the real differences are due to the retro-nasal olfaction of the volatile organic compounds in the bouquet of the wine and from the liquid itself as it enters the mouth and is swallowed.

Since the two thousands (2001, 02, 03 and beyond…), Riedel was alone in banging the drum for shape affecting flavour, and those who first encountered this message were convinced it was suggestion, marketing or some other subliminal trickery. Despite using the now debunked ‘tongue map’ as part of the explanation to explain the differences in perception of flavour, Riedel went from strength to strength demonstrating those differences. Science too has come a long way in its understanding and communication of retro-nasal olfaction, unintentionally backing up what Riedel anecdotally sensed. Zalto then arrived on the market in 2006 and with their revolutionary straight sided mouth-blown glasses, showed even more clearly how shape impacts flavour.

Now there is an acceptance of another previously neglected component of the impact of the wine glass on retro-nasal olfaction. That component is the process by which the wine glass is made.

Historically, all glass was blown by mouth. A glass blower would place a ball of molten glass on the end of a long tube and blow the glass into a mold, to form the required shape. With technology, machines were in some way able to replicate this process, but up until relatively recently, not even close to the craftsmanship and fine work achieved by the mouth blower. The machines blow with far greater force and speed, whereas mouth blowing is slower and more gentle, with many lungfuls of air used while the pipe is rotated. The best machine made glass is still not able to produce wine glasses as fine and as perfect as the best mouth-blown bowls and stems, yet aesthetically, the best machines are very good. You can view the mouth-blowing process here: Zalto Production Video.

The end result of the 2 different processes, is that the internal surface of the wine glass bowl blown by mouth is rough (when viewed under a microscope) and as smooth as oil when blown by machine. The rough surface creates what is essentially a larger surface area, in a similar way to the fact that our lungs or small intestine have a large surface area, plus it is guessed that the rough surface provides some drag, slowing the descent of the volatile organic compounds in the bouquet above the liquid, after swirling. In contrast, the completely smooth internal surface of machine-made glass does not impact the wine’s aroma in the same way.

There are very few companies producing exactly the same glass bowl shape with only the process as the difference. Nevertheless, it is possible to find some examples and you are encouraged to taste the same wine, side by side, from near identical machine-made and mouth-blown glasses to see the difference. A number of independent wine professionals have perceived a marked difference in the fullness of the aroma and especially the length and intensity of the finish from mouth-blown glasses. The better the wine, the bigger the difference.