Theoretical aspects of impregnation sealing are reviewed to give a basis for practical discussion. A brief history of the evolution of impregnation techniques is offered. Specific applications covered are impregnation of both die cast and powder metal components for pressure and fluid retention, plating and other surface finishes, and increased machinability. Actual case histories are cited. Processing techniques as related to components on a production basis are discussed and guidelines established. Equipment developments and process refinements are explored.