Chapter 3 97 were introduced to overcome the insolubility of silicones in shampoo compositions, but this drastically reduced the amount of silicone deposited onto hair and compromised conditioning performance. Clear, silicone-containing conditioning shampoos have been formulated by adding trideceth-2 carboxamide MEA to reduce the silicone droplet size.54 Transparent conditioning shampoos can be formulated by incorporating the silicone as microemulsified droplets, but the small microemulsion droplets tend to be rinsed away rather than deposited during the shampooing process. Moreover, coalescence of the droplets can lead to loss of transparency in the product during storage. Attempts have been made to overcome these challenges by including silicone emulsions with high internal viscosities, typically greater than 100,000 centistokes, but the high internal phase viscosity gives deposited silicone that is can be difficult to remove and this causes buildup with each consecutive shampooing. Such buildup usually reduces the volume of the desired hair style and causes “droop” and flatness. Fortunately, shampoo compositions providing superior conditioning to hair while also providing excellent storage stability and optionally high optical transparency or translucency can be obtained by combining low viscosity microemulsified silicone oil with cationic cellulose polymers and cationic guar polymers having molecular weights of at least about 800,000 and charge densities of at least about 0.1 meq/g.55 Conditioning shampoo formulations that include a silicone microemulsion in a conditioning shampoo containing guar hydroxypropyltrimonium chloride and an anionic detersive surfactant have also been reported to be clear.56,57 If pre-gelatinized starch, such as hydroxypropyl distarch phosphate, is included with polyquaternium-10, transparent conditioning shampoos can be obtained.58 Another way to minimize buildup is to treat the hair with water- in-water emulsions that can be prepared by including cationic polymers with soluble salts in surfactant compositions.59 These water- in-water emulsions provide conditioning benefits with good spread of the conditioning phase on the hair and less chance of buildup.