Orris Concrète Oil

#### Orris (Concrète) Oil. **Orris "Concrète" **(so-called) is not a true concrète according to the definitions in Part One of this book. It just happens to be a solid ("concrète") essential oil. It is commercially known as "**Orris Butter**" or **"Beurre d'Iris**". It is produced by steam distillation of the rhizomes of **Iris**** ****Pallida**, one of the most decorative garden perennials. The rhizomes (subterranean stems) are washed, decorticated and dried. They should be stored subsequently, well protected against insect and fungus attack, for three years. The fresh rhizomes are practically odorless. Prior to distillation, the rhizomes are pulverized. Unpeeled orris rhizomes are occasionally used, e.g. in Morocco where the plant is **Iris Germanica **and, more recently, also the **Iris Pallida.** The distillation of pulverized orris rhizomes demands much experience and involves quite a few problems. The extremely small yield of liquid oil, the high amount of starch in the rhizomes, the volume of the pulverized material, etc. all create problems for the distillers. Production of orris (concrète) oil takes place in France and Morocco, to a lesser degree in Italy where the bulk of the botanical material is still produced. Smaller amounts of the oil are distilled in England and the U.S.A. The distilled oil solidifies in the receiver to a wax-like, cream-colored mass known as **Orris**** ****Butter**** **or **Orris**** ****Concrète.**** **It is solid because of its high content of myristic acid, a white, stearin-like substance (see also **Ambrette Seed Oil).** Orris (concrète) oil melts at about body temperature, and has a woody, fatty-oily but distinctly violet-like odor, with a fruity undertone, sweet- floral, warm and tenacious. When freshly prepared and well stored, it should not possess perceptible notes of myristic acid or decomposition products thereof (acid or unsaturated-fatty notes, rancid notes, acrylic notes, etc.). The concrète oil is not soluble in ethyl alcohol at room temperature, and the myristic acid also causes trouble directly because of its acidity when compounded with other perfume materials. Consequently, myristic acid is considered undesirable from a perfumery point of view, although it has certain advantages (fixation of the delicate odor of the irones, etc. It can be shipped in aluminium cans which are unbreakable and thus prevent loss of material; some consumers want to produce the absolute according to their own specific methods and needs). **Orris (Concrète) Oil **is used in perfumery as such when the presence of myristic acid is not prohibitive, e.g. in soap perfumes where the weak acid only acts as a fixative. Incidentally, the methyl and ethyl esters of myristic acid are often used as blenders in violet type perfume bases. The isopropyl ester is high-boiling and odorless and is a popular solvent for cosmetic products, or a co distiller for absolute oils. The high cost of orris (concrète) oil limits its application to a certain degree, but even small percentages of this exquisite material lends very fine effects to various perfume types other than the old-fashioned violet: mimosa, cyclamen, freesia, orchid, robinia etc. as well as other delicate floral. A true **Orris**** ****Concrète**** **is also produced, and it has become an increasingly popular intermediate in the production of Orris Absolute. The orris rhizomes are extracted with petroleum ether to yield a dark amber colored, viscous extract which is free from myristic acid. This "concrète" which looks more like a resinoid, is then extracted with ethyl alcohol to yield an absolute of orris. Benzene can be used in place of petroleum ether; it gives a higher yield (see **Orris**** ****"Resinoid"**, following monograph), but it is darker, and the last traces of benzene odor are very difficult to remove. Petroleum ether can be obtained in a higher grade of purity (free from higher boiling, ill-smelling components) and rarely leaves any residual odor. The annual world production of **Orris (Concrète) Oil **is in the order of magnitude of one metric ton.