Hydrosols, what we call them in the States, are made when distillation takes place. Plant material aka biomass in the still, can be set to distill essential oils or hydrosols. Even when distilling for essential oils, there is some hydrosol, however distilling specifically for hydrosol gives greater essential oil in the hydrosol and greater amounts of hydrosol.
In the still, steam rises and is pushed thru the biomass, where it is forced into a narrow tube that is surrounded by another tube where cold water flows thru, forcing the steam to turn into droplets of essential oil and/or water.
Hydrosols are aromatic, containing many water soluble fragrant materials found in the plants they are derived from, holding similar medicinal properties to their essential oil counterpart, but are less concentrated.
More to come.