Chapter 13 421 effect on hair volume and body, while providing enough oil to enhance hair shine, condition, and styling. The level and type of neutralizing agent, for those fixative polymers that require neutralization such as those with a carboxylate group, will tend to affect film properties as well. Organic amines such as aminomethylpropanol (AMP) and triethanolamine (TEA) will have a more plasticizing affect than an inorganic alkali such as NaOH. Organic amines may reduce film hardness and in some cases high humidity curl retention. Besides the fixative, fixative modifying, and gelling ingredients, there are a few other components that are necessary to complete the formulation of a hair gel. These include preservatives, chelating agents, UV absorbers, fragrance and fragrance solubilizers, feel modifiers, and color. One can get the impression from this that formulating a fixative product could get quite complex—and we’ve yet to even mention the processing that goes into making each type of formulation. The formulation challenges become magnified when the product format contains a novel texture. A guiding principle or formulation strategy to keep in mind is to be specific on the profile on the desired product that needs to be made, with respect to both aesthetics and performance, and choose appropriate ingredients that will achieve this. It needs to be stressed that during formulation development, always evaluate performance in parallel with aesthetics. Many a formulator has spent too much time in getting the right type of foam in a mousse or feel in a cream only to discover that the added foaming or feel modifying agents lowered the required performance efficacy. Advances in fixative polymers: The first synthetic resin promoted for hair styling was polyvinylpyrrolidone (PVP) in the 1950s.4 PVP can be incorporated into clear gels due to its excellent water solubility and compatibility with gelling agents such as carbomers. The resultant resin that forms on the hair imparts stiffness to the hair. Very early in PVP’s career, many drawbacks to its resinous film became evident, such as poor humidity