Hay absolute

Sun-dried grass, sweet tobacco, dry tea, almond, pale honey. Clear coumarin warmth with an earthy tone. A light leathery drydown.

Hay absolute has no dedicated IFRA standard, but coumarin, its key constituent, is restricted by IFRA (2020) per product category. Coumarin is also a labelled allergen in the EU above 0.001 percent in leave-on or 0.01 percent in rinse-off products.

Composition varies with grass species and cutting season. Store dark, sealed and cool.

Hay's odour comes mainly from coumarin. When grass is cut and dried, glycosides in the leaf break down and release coumarin. Fresh grass therefore barely has this smell; dry hay does.

An absolute is made in two steps. The raw material is extracted with a non-polar solvent such as hexane to give a waxy concrete. The concrete is then washed with ethanol, chilled to precipitate waxes, filtered and freed of alcohol. What remains is the absolute.

The grass mix used is usually rich in sweet vernal grass (Anthoxanthum odoratum). Some producers add other herbs. With no single species, each producer's absolute has its own profile.

In perfumery hay absolute bridges aromatic herbs and amber. It plays a role in fougères, tobacco accords and pastoral structures. William Henry Perkin synthesised coumarin in 1868; Fougère Royale (Houbigant, 1882) is the first well-known fragrance built on synthetic coumarin.

Because coumarin is IFRA-restricted, the maximum amount of hay absolute depends on the coumarin content of the lot. The supplier's certificate of analysis is the basis for calculation.

Hay cutting in Europe usually falls in early to mid summer. The grass must be fully dried before extraction to avoid fermentation.