Chapter 3 95 a small degree of hydrophobic substitution in the cationic guar derivatives.43 Synthetic copolymers of acrylamide and a Triquat monomer are postulated to provide improved deposition on hair and improved conditioning performance with respect to wet combing.44 Silicones have become standard ingredients in many conditioning shampoos for the smooth, silky hair feel that they confer. Silicones were introduced to shampoos as 2-in-1 conditioning agents in the 1980s. The introduction of silicones needed to overcome two substantial deficiencies: (i) silicones are well known defoamers, and (ii) silicones are incompatible with typical shampoo compositions and they tend to separate due to their low specific gravity. Initial attempts to stably suspend the silicone included the use of water– miscible saccharides such as corn syrup.45 Later products comprised xanthan gum in the shampoo as a suspending agent and acceptable foaming attributes were conferred on the shampoos by formulating with relatively high levels of alkyl sulfates as the primary surfactant, cocamide MEA as the co-surfactant, and ethylene glycol distearate as a surfactant structuring agent.46 In the actual application there is a technical contradiction involved in the deposition of silicone conditioning components from a detersive, cleansing system the detersive system is designed to remove oil, grease, dirt, and particulate material from the hair and the conditioning agent has to be deposited on that same hair in one process. As a result, large excess amounts of silicone are used to ensure deposition and one consequence of this is that large amounts of the expensive conditioning silicone can be rinsed away rather than deposited on the hair. Cationic polymer/anionic surfactant coacervates enhance the deposition of silicones on hair and, consequently, increase the efficiency of conditioning shampoos.47,48 Volatile cyclic siloxanes confer the desired silky initial feel, but these materials are difficult to formulate in consistent homogenous formulations and they tend to spread uncontrollably over hair and skin.49 This effect can be controlled with polymeric silicone gels formed in volatile silicones to provide both the initial silky feel and