Preform and hot-fill blow-molded container having reinforced finish

In a preform used to make a blow-molded container having a reinforced finish capable of maintaining stability during and after hot-fill processing, the finish having a top surface, an inner peripheral surface extending from said top surface defining an inner finish diameter, and an outer peripheral surface extending from said top surface defining an outer finish diameter, the outer peripheral surface having a thread for cooperating with a cap to seal the container, the finish having a width at said top surface defined by a distance from the inner peripheral surface to the outer peripheral surface, the improvement comprising an insert permanently attached to the finish and forming a portion of the top surface of the finish, said insert being ring-shaped, made from plastic having greater rigidity than the finish, and positioned entirely above the threads, said insert having an inner diameter at least as large as the inner finish diameter and an outer diameter no greater than the outer finish diameter, and said insert having a width between said inner diameter and said outer diameter which is less than the width of the finish at said top surface.