Steam distillation: Not so simple

True Essential Oils are obtained by slow and gentle steam distillation. The control of the distillation parameters requires more than just experience, it is a true art.
The plants are placed in a closed vat through which a current of steam is passed freeing the aromatic molecules.
The steam which is laden with these molecules then passes through a cooling coil.
At the end of the coil, the water (hydrosol) and Essential Oil is collected in a separator or "essence recipient" which is then separated due to the difference in density as the oil is lighter than the water and floats on the surface (except for some rare oils which are heavier).
Extraction using organic solvents should be banished from our ethics. (One exception in our Essential Oils, jasmine absolute).

Distillation equipment "Alambic"

The quality of the essential oil depends to a large extent on the control of the distillation parameters

It is even better when:

the temperature is as low as possible
the pressure is as low as possible (0.1 to 0.2 bars)
the distillation speed is as slow as possible
spring water is used
the plants are at a good botanical harvest stage
the still and essence recipient are made of stainless steel or (better according to certain people) of copper

Expression (by pressure) is used for certain plants, in particular for citrus fruit

Extraction by expression: it is the simplest process of all, but it is only suitable to fresh aromatic peel, such as the zests of Hesperides (lemon, orange, grapefruit, bergamot, sweet lime ...).
Generally speaking expression is carried out using hydraulic presses.
Rather than talking about "Essential Oils" we use the term "Essences".