An SMC low profile resin system is a mixture, generally consisting of unsaturated polyester, thermoplastic low profile additive, and styrene. Typically, the amount of each component in the resin has been established by evaluating the performance of a series of blends having different levels or ratios of thermoplastic and unsaturated polyester. Using this method to identify the optimum composition is often highly subjective and inefficient. Since the resin is a mixture, the levels of the components cannot be varied independently; an increase in the level of one component results in a corresponding decrease in the percentages of the other components.