Enfleurage is the traditional method used to extract the finest quality essences from delicate flowers, such as Rose and Jasmine. It is a laborious and therefore costly process, which accounts for the high price of these oils, or absolutes.
Sheets of glass are coated with fat, usually purified lard or beef fat, and freshly picked petals are sprinkled over the fat. The glass sheets are stacked in tiers in wooden frames, and the essence from the petals is absorbed into the fat. The faded petals are removed and fresh ones spread over the fat for many days, sometimes as long as three weeks in the case of jasmine, until the fat can absorb no more essential oil.
The fat is then collected and cleaned of any debris, such as stale petals or stalks. At this stage it is called a pommade. The pommade is then diluted in alcohol and shaken vigorously for twenty-four hours to separate the fat from the essential oil. Oils produced by this method are known as 'absolutes', and are very concentrated in character. Their perfuming power and therapeutic properties are very strong indeed, and far smaller amounts are needed to give the same effect as with distilled oils. Some absolutes, such as Rose, solidify at normal room temperatures and return to a liquid state when the bottle is gently warmed by being held in the hand for a few moments.
An alternative method of enfleurage employs sheets of muslin saturated with olive oil. These are stretched on wooden frames, and stacked in racks in the same way as the glass frames. Flower petals are spread over the oil-soaked cloths and renewed each day until the olive oil has absorbed as much essence as it can hold. It is then technically known as 'huile antique' or 'huile Francaise' and can then either be used as it stands as a perfumed body oil, or treated with alcohol to separate the essential oil.
These two methods have been used traditionally in the perfume industry, especially around Grasse, to produce the very highest quality aromatic oils, but only about 10% of essential oils are now produced by this method, as it is so time consuming and expensive. About 80% of Rose and Jasmine oils are now extracted by means of volatile solvents, the remaining 10% being obtained by distillation.