Botanical extracts are highly concentrated aromatic substances derived from plant material. The terminology surrounding these extracts, however, can often be confusing, particularly the distinction between an essential oil and an “absolute.” While both types of products contain the volatile aromatic compounds of a plant, an absolute is a specific, potent form of extract that differs fundamentally in its chemical makeup and the method used to obtain it.
The Chemical Definition of an Absolute
An absolute is chemically defined not as a pure, volatile oil, but as a complex, highly concentrated liquid derived from a waxy intermediate known as a “concrete.” This final product is a viscous, sometimes semi-solid substance that includes more than just the plant’s volatile aromatic molecules.
Unlike true essential oils, which are composed almost entirely of volatile compounds, absolutes contain non-volatile components. These non-volatile elements typically include plant waxes, pigments, and resins, which are co-extracted during the initial phase of processing. Because of the presence of these heavier molecules, an absolute is technically not a pure essential oil.
Solvent Extraction: The Necessary Process
The unique chemical composition of an absolute is a direct result of the specific, multi-stage process required for its creation, known as solvent extraction. This method is necessary for botanicals that are too delicate or have an extremely low yield, such as jasmine, tuberose, or mimosa flowers. The gentle aromatic compounds in these plants would be damaged or destroyed by the high heat and steam used in traditional steam distillation, making the solvent method the only viable option.
Creating the Concrete
The process begins by washing the plant material with a low-polarity, volatile chemical solvent, such as hexane. This solvent dissolves the aromatic compounds along with other lipid-soluble materials like waxes and pigments. The solvent is then removed, typically through a vacuum distillation process at low temperatures, which leaves behind a thick, waxy, aromatic mass called the “concrete.”
Refining the Absolute
The concrete is not the final product; it must be further refined to create the absolute. This second stage involves treating the concrete with a different solvent, usually high-proof alcohol like ethanol. The aromatic compounds are soluble in the ethanol, while the unwanted, non-fragrant waxes remain insoluble.
The mixture is chilled and filtered to remove the waxy solids. Finally, the ethanol is removed through low-temperature vacuum distillation. The final, purified extract that remains is the absolute, having gone through this three-step process of solvent extraction, alcohol washing, and alcohol removal.
Practical Differences and Considerations for Use
The unique extraction process results in an absolute that possesses distinct physical and aromatic characteristics compared to a steam-distilled essential oil. Absolutes are typically much thicker, often appearing as a deeply colored, viscous liquid or a soft paste, due to the presence of heavier, non-volatile molecules. This viscosity contributes to a much more tenacious and longer-lasting aroma, often described as being closer to the scent of the fresh flower.
The concentration and olfactory depth make absolutes highly valued in the world of fine perfumery, where they provide deep, complex base notes that are not achievable with lighter essential oils. For example, Rose absolute is known for its dark, honeyed aroma, contrasting with the lighter notes of Rose essential oil. Because of the labor-intensive process and the large amount of raw plant material required, absolutes are typically the most expensive form of botanical extract.
A key consideration for users is the possible presence of trace amounts of the chemical solvent used during the initial extraction phase. While manufacturers aim to remove all of the solvent, a tiny residue may remain. For this reason, absolutes must always be properly diluted with a carrier oil before any topical application to avoid skin sensitivity. Common examples of extracts almost exclusively found as absolutes include jasmine, tuberose, and narcissus.