What the words on the label mean

This is the most common form and also the one whose GC/MS analysis is easiest to read, because its composition is relatively simple.

Easily confused. A note on the scope of this word. The ISO 9235 standard classes mechanically expressed citrus-peel oils as essential oils too, so by the industry standard essential oils come by two routes: distillation, and cold pressing of citrus peel.

This page treats them as two entries because their chemical profiles differ clearly — the pressed version carries the non-volatile group that the distilled version lacks. That is our convention for readability, not a boundary drawn by the standard. On commercial labels both are called essential oils, and both correctly.

Used directly on the skin without dilution. For some species the hydrosol smells quite different from the essential oil of the same batch, rather than being a faint version of it.

Easily confused. A hydrosol is not essential oil mixed with water. It is a separate product with its own composition, and it spoils much faster because it contains water.

Used for flowers that cannot stand heat — jasmine, tuberose, orange blossom, mimosa. It is the only way to get the real smell of these flowers at commercial scale.

Easily confused. An absolute is not an essential oil and should not be called one. It is thicker and darker, and its analysis contains heavy compounds an essential oil never has.

Rarely sold at retail. Mainly a raw material for producing absolutes, or used in scented waxes and candles.

Easily confused. Because it contains wax, concrete does not dissolve in carrier oil the way an essential oil does. Using it by mistake gives a lumpy, uneven mixture.

Used when you need a composition as close to the raw material as possible, or when the material contains valuable compounds that cannot stand heat.

Easily confused. CO₂ extracts come in two forms: subcritical gives a lighter product, supercritical a fuller one. Labels often do not say which, and the two differ considerably.

Mainly used as a fixative: the non-volatile resin holds the lighter compounds on the skin for longer.

Easily confused. Resinoids are sticky and very hard to clean off equipment. They can also crystallise in the cold, and that is not a sign of spoilage.

Used in food, where both smell and pungency are needed in a single ingredient.

Easily confused. Pepper essential oil has only the smell and no heat; pepper oleoresin has both. This is the most easily confused pair in this table, and buying the wrong one gives an entirely wrong product, not a slightly wrong one.

Soaked in alcohol to draw the smell out of the fat, giving enfleurage absolute. Today it survives almost only at craft and demonstration scale.

Easily confused. Almost never found on the market. If you see the word pomade on a modern product label, it is most likely a trade name rather than a genuine enfleurage product.

Used only for citrus peel. It is the only way to keep the smell of fresh peel exactly as when you squeeze it.

Easily confused. Furocoumarins — bergapten is the one most often mentioned — are why cold-pressed citrus oils are photosensitising while distilled ones are not. The safety page on photosensitivity covers this in detail.

Don’t confuse furocoumarins with coumarin. They are different groups: coumarin proper is abundant in tonka bean and cassia bark, and it does not cause photosensitivity by the same mechanism. Carotenoids are a group of pigments, and they explain why pressed oil is coloured and distilled oil clear.

Used in food and perfumery when a stable citrus smell is needed. It is stronger than ordinary essential oil, so less is needed.

Easily confused. The order of the steps is often told backwards. Folded oil starts from the COLD-PRESSED oil, which is then fractionally distilled under vacuum to draw off terpenes — not steam-distilled first and then folded.

The reason is technical: what is worth folding is the pressed oil, because it keeps compounds the distilled oil has lost. Removing limonene from the pressed oil gives something richer and more resistant to oxidation; doing the same with distilled oil adds little value.

A consequence worth knowing: fractional distillation also removes most of the furocoumarins, so folded oils are usually less photosensitising than whole pressed oils.

Used directly on the skin without dilution, because it is itself a carrier oil. That is its biggest practical advantage.

Easily confused. An infused oil is not essential oil diluted in carrier oil. The concentration of aromatic compounds is much lower, and its analysis is dominated by the carrier oil rather than reflecting the plant.

Brewed to drink. It is not used as an ingredient for other products, because there is no concentrated form.

Easily confused. Genuinely scented tea keeps its smell through several infusions; flavour-sprayed tea is strong in the first infusion and then disappears from the second. It is a test anyone can do.