The above analysis regarding shrinkage pertains to in-place dimensional changes in the plastic moldings.When moldings distort or bend out of plane,then war page is occurring.In some applications, the dimensional changes due to war page can far exceed the shrinkage.Worse.war page can be more difficult to predict and correct.While an exhaustive analysis is outside the scope of this book,some practical guidance is provided for mold design.While all war page is due to differential shrinkage,the sources of the differential shrinkage vary.The simplest cause of differential shrinkage may be a temperature gradient through the wall thickness of the molding.