// Definition
A centuries-old extraction technique adapted for cannabis terpene isolation in which plant material is heated with steam, causing terpenes to volatilise at temperatures significantly below their normal boiling points. The interaction between water vapour and oil-based terpenes reduces their effective boiling points by roughly one-third, allowing gentle recovery of essential oils.
// From the Episode
Mark Scialdone provided detailed chemistry explaining the phenomenon: water-immiscible terpene molecules experience dramatically lowered boiling points in the presence of steam because the total vapour pressure of the mixture equals the sum of the individual vapour pressures. He connected this principle to why moisture content in flower affects rosin pressing yields — the water in the bud, when heated above its boiling point, essentially steam-distils the essential oils onto the parchment paper.