Bulk Molding Compound (BMC) is a mineral filled, fiberglass reinforced polyester (vinyl ester and phenolic) based molding compound. BMC is a thermosetting material that undergoes an irreversible cross-linking reaction when exposed to the heat and pressure of the thermoset molding process (i.e. ambient delivery of material to a heated molding surface). A somewhat tacky, dough-like mass in its unmolded state, BMC is converted to an infusible, solid state using injection, compression and transfer methods.

BMC provides a competitive alternative to die cast and drawn metals, sheet molding products and engineering thermoplastics. Notable BMC properties include resistance to creep and discoloration when exposed to heat and load, notched impact performance, high modulus and surface durability (resistant to reagent/stain, chemical, scratch and ultra violet attack). BMC can be formulated to meet specific a performance profile. This unique customization allows for the elimination of costly additives and reinforcements where possible. This "cafeteria approach" to material development sets BMC apart when evaluating price versus performance properties.