When the plant material is too fragile to be distilled, organic solvents - such as hexane, are used to extract the lipophilic materials. This method also extracts the chlorophyll and other plant tissues, creating a vibrant color or thick extract. The solvent is pumped through the plant material, which is packed tightly. The concentrate produced, known as a concrete, is then mixed with alcohol and heated to extract the aromatic compounds of the plant. The mixture is vacuum distilled to remove the alcohol and create an ‘absolute’.