Hydrosols, also known as floral waters, hydroflorates, flower waters or distillates are products from steam distilling plant materials. Hydrosols are like essential oils but in far less of a concentration. When a distiller brews plant material with water in a large cooker the steam fills the pot and, as it rises, it causes the glands of the plants to burst and release the oils and essence of the plant into the steam. The oil rises through a condenser and collects in a separate vessel.
The science of distillation is based on the fact that different substances vaporize at different temperatures. Unlike other extraction techniques based on solubility of a compound in either water or oil, distillation will separate components regardless of their solubility. The distillate will contain compounds that vaporize at or below the temperature of distillation. The actual chemical components of distillates have not yet been fully identified, but distillates will contain essential oil compounds as well as organic acids and other water-soluble plant components. Compounds with a higher vaporization point will remain behind and will include many of the water-soluble plant pigments and flavonoids.