The automotive industry's need for thinner, smoother and tougher low profile sheet molding compound (SMC) composites for the evolving body panel parts of the 1980s has prompted the development of Union Carbide Low Profile Additives XLP-4514 and XLP-8521. Composites utilizing these additives have provided Class A surface characteristics at 80 mils thickness and above on developmental deck lid tools. Also improved surfaces on commercial parts such as a variety of models of grill opening panels, truck hoods, etc. have been observed. These studies were conducted using computer assisted experimental designs and results-analysis to ensure valid conclusions.XLP-4514 was engineered for use with modified rigid resins currently employed widely with Union Carbide Low Profile Additive LP-40A. XLP-8521 provides Class A surface with new, proprietary tougher resins as well as yielding composites with both superior surface and composite toughness.