Chapter 13 425 with a secondary resin at a lower level to help with one or more hair attributes. One strategy to obtain the correct blend of polymers to achieve multifunctional benefits is to use an experimental mixture design technique. An example of this was demonstrated by M. Philbin, et al.11 Polyvinylformamide and two viscosity grades of polyvinyl alcohol were blended at specific ratios specified by a design of experiments (DoE) computer program. After data collection of the key hair attributes and multiple regression analysis, the optimal range of ratios of the three polymers was identified to provide the best clarity in the gel, curl compression, high humidity curl retention, and reduction in flaking compared to PVP. The identification of this “sweet spot” was an alternate way of obtaining the correct multifunctional benefit by using a resin blend instead of blending the appropriate monomers in a newly synthesized copolymer. The formulator can utilize this blending technique to not only achieve a full range of performance properties but also to help with compatibility, reduce the cost of a formula due to the use of an expensive ingredient through blending with a cheaper material, or to add another property in which that one polymer is deficient. When polymers become structurally more complex, applications research may reveal other features of the resinous film besides styling—either physical properties given to the formulation or new performance attributes. As an example, some fixative polymers have been found to have a dual role of providing fixative as well as rheological attributes. One such polymer is acrylic acid/VP cross- polymer. Like carbomers, it is based on cross-linked polyacrylic acid and it will form clear shear thinning gels that can suspend particles due to its yield value. Because of the copolymerization with VP, the polymer also has hold properties.12 Another example is polyacrylate-14 which is a lightly cross-linked acrylate copolymer of C 1-4 alky(meth)-acrylate, (meth)acrylic acid, and a proprietary mixed hydrophobe package. This polymer can form clear shear thinning gels and have a host of hair styling benefits such a high humidity