Plastics are materials that under certain conditions have a convenient and useful range of plasticity. In general, something must be done to the material to bring it into the plastic state for purposes of molding; and, in general, something quite different must be done to make it again non‐plastic. The first step in processing the material is termedplasticizing, the last is in some cases termed curing, but may, perhaps in general, be more appropriately termeddeplasticizing.