Navigate the challenging waters of the world of botanical extracts, distillates, waters, hydrosols, and essential oils in cosmetics with this quick guide. Learn to differentiate between plant derivatives to improve your skin care.
The difference between essential oils / botanical extracts / distillates / waters / hydrosols
The term 'essential oils' refers to aromatic substances derived from plants by steam distillation or solvent extraction. Hydrosols and floral waters are the condensed water derived from the distillation process. They all smell different because their chemical compositions are entirely distinct. Sometimes, floral waters or distillates are actually the residual waters collected after washing the flowers, stems, and leaves before processing them. In rare cases, some suppliers even try to sell just water combined with an essential oil and a solubilizer (what a pain!).
It's not that one essential oil or hydrosol is better. They all have their function; formulators choose one or the other depending on their properties and the desired outcome. Some functional substances are oil-soluble, like vitamin A, while others are water-soluble, like some interesting sugars that are highly hydrating.
Below is a quick guide to plant extraction methods where solvents are used. These are substances that dilute functional molecules, leading to a solution (extract):
Alcoholic: They are very rich in active ingredients, as alcohol, unlike water, is capable of extracting almost all phytocomplexes from raw material. Alcohol, in addition to having superior solvent power, acts as an excellent preservative.
Ethereal: When only ethers like ethoxydiglycol are used in extraction.
Glycolic: Extracted with glycols. Most of them are synthetic, but some natural equivalents exist, such as in the case of butylene glycol or propylene glycol.
Aqueous: Simple extracts based on medicinal herbs. These are classic decoctions and infusions.
Hydroglycerinates: Obtained by maceration in distilled water and glycerin.
Hydro-glycerol-alcoholic: Extracts obtained using a mixture of glycerin, alcohol, and water.
Tinctures: Water and alcohol-based extracts using fresh plants (mother tincture) or dried plants (classic tincture).
Oleolites: Obtained by maceration in vegetable oils.
Dry plant extracts are presented as powdered preparations, but they cannot truly be considered powders. The latter, in fact, are obtained by pulverization, without any solvent extraction.
Enfleurage: A traditional technique used by the perfumery sector to extract essential oils and essences from flowers.
Supercritical fluid extraction: To extract specific substances from plants using supercritical carbon dioxide. Its name refers to the intermediate stage between the gaseous and liquid states, where the solvation and permeability capabilities of the solvent are at their maximum.
Distillation: A very versatile method used for extraction and purification, which involves combining pressure and temperature.
Maceration: The plant is soaked in a container along with a solvent. This type of extraction yields a liquid extract, called a macerate.
Infusion: Where boiling water (the solvent) is poured directly over the crushed plant.
Decoction: Where the plant, along with the solvent, is heated for a period.
Percolation: Where the solvent (by gravity or under pressure) passes through a layer, usually homogeneous, of pulverized plant.
Cold pressing: A vegetable oil that is usually cold-pressed from fruits, nuts, and seeds, as in the case of olive oil.
How botanical extracts are used in cosmetics
Hydrosols, distillates, and floral waters are frequently used in toners or when it is desired to increase the percentage of organic/natural matter in a formula by replacing pure water. Essential oils have many properties, but their use in cosmetic formulas must be approached with great care, as their negative effects (irritation) sometimes outweigh their benefits. This is why they are usually used in small quantities only to perfume the final product or to mask the scent of other ingredients present in the formula.
Personally, when I formulate, I choose botanical extracts that have been exhaustively studied for use on very sensitive and reactive skin. This means selecting not only botanical ingredients with highly beneficial properties for the skin but also opting for the most respectful extraction method for it. Once I am satisfied with the scientific results, I must admit that I usually use botanical extracts at their top possible potency, so the skin benefits from them to the maximum. I love using large doses of what truly works on the skin in my formulas.
