For these three reasons, all molds will benefit from the procedures described below. A Class 'A' finish is a perfectly polished high luster surface free of porosity and scratches of any kind. The term originated in the marine and automotive industries. Examples of such a finish can be found on high quality boat hulls and automobiles. However, those finishes are achieved through two different procedures.
Cars have primers and paint systems sprayed over medium quality metal surfaces.
The paint flows into a self-leveling thin film and requires polishing to achieve a true Class 'A' surface. The boat hull, however, receives its finish directly from the mold itself. If the mold has a Class 'A' finish all the parts produced in it will also have the same high quality surface. Construction of quality molds can decrease final finishing time and increase overall part quality. A Quality Mold Surface Begins At the Plug Stage.