As a molded product cools, it tends to shrink. This is a natural reaction of plastic. The molecular structure of the resin usually determines the amount of shrinkage. Using gas assist, the mold is never completely filled; gas pressure and time complete the fill. The part is uniformly packed out, eliminating the differentials of pressure within the cavity, which promotes a large reduction in postmold shrinkage and warpage. The evenly applied gas pressure can help eliminate many of the problems inherent to conventional injection molding.