Similar to essential oils, absolutes are concentrate, highly-aromatic, oily mixtures extracted from plants. Whereas essential oils can typically be produced through steam distillation, absolutes require the use of solvent extraction techniques. First, an organic solvent, such as hexane, is added to the plant material to help extract the hydrophobic compounds. This solution is filtered and concentrated by distillation to produce a waxy mass called concrete. The lower molecular weight, fragrant compounds are extracted from the concrete into ethanol. When the ethanol evaporates, an oil—the absolute—is left behind.