Often the volatile oil content of fresh plant parts (flower petals) is so small that oil removal is not commercially feasible by the aforementioned methods. In such instances, an odorless, bland, fixed oil of fat is spread in a thin layer on glass plates. The flower petals are placed on the fat for a few hours; then, repeatedly, the old petals are removed, and a new layer of petals is introduced. After the fat has absorbed as much fragrance as possible, the oil may be removed by extraction with alcohol. This process is known as enfleurage and was formerly used extensively in the production of perfumes and pomades.