Surfactant molecules can be synthesized to achieve specific solubility characteristics often referred to as the hydrophilic-lipophilic balance (HLB). The capability of a surfactant to modify herbicide penetration is partially attributable to the HLB, with each herbicide-species interaction having an optimum HLB requirement for the surfactant employed. HLB numbers for surfactants are often given on technical information sheets for specific products. They range from 0 to 40 with most of them between 1 and 20. Low HLBs are very oil soluble, while higher HLBs prefer water.