A process for impregnating at least one porous part with an impregnant comprises: (a) immersing at least one porous part in a fixed volume of impregnant, (b) measuring at least one parameter indicative of the effective volume of the impregnant as the impregnant impregnates the porous part(s), and (c) interrupting impregnation when the measured parameter(s) indicates a desired level of impregnation is achieved. An apparatus for impregnating porous parts comprises a vessel for holding at least one porous part and a fixed volume of impregnant, and at least one device for measuring the change in effective volume of the impregnant within the vessel.
