Concretes and Absolutes are highly concentrated aromatic materials extracted from plants. The multi-step process includes first extracting the aromatic oil from the plant material with a solvent such as hexane. After the hexane is removed what is left behind is a waxy substance called a concrete. This semi-solid to solid highly fragrant material contains a large amount of pigments and waxes. Due to their waxy texture, concretes are perfect for making solid perfumes. They have a somewhat delicate, yet long lasting aroma and are soluble in both carrier oil and alcohol, though often it is necessary to filter any insoluble waxes and solid material that remains.