Method for obtaining a pressurized hydraulic seal by making and applying a reticular seal element to a sliding member slidable in a housing cavity for housing an apparatus and configured for controlled recirculation, mixing and frontal expulsion of chemically reactive polymer components, said reticular seal element being conformed for preventing the transfer from and to slots, provided on said member, for the recirculation of the reactive resins, the method comprising the steps of: - a0) obtaining, in the cylindrical part of the surface of said sliding member, housing seats for said reticular seal element, said housing seats being shaped as recesses that extend according to a closed reticulation distribution around said recirculation slots to contain and fix said reticular seal element, - a1) shaping these housing seats with sections suitable for retaining said reticular seal element, exerting a friction force that is greater than that arising from the free surface sliding of said reticular seal element with respect to the housing surface in which said member slides, in which for making said sealing gasket element: - a2) a precursor element of said seal gasket element is obtained from an elastoplastic material, by shaping said precursor element with a grid structure having a reticular shape corresponding to said housing seats, - b) positioning said precursor element around the recirculation slots for the resins of said sliding member at the housing seats, - c) exerting on said precursor element, by one or more temporary clamping and preliminary deformation elements (C0, C1, C2, C3; C4), a compression action for radial contraction and longitudinal adaptation that are suitable for pressure inserting, adapting by deformation to the shape of the housing seats and coupling by deformation said precursor element in one or more housing seats provided on said sliding member so as to apply by deformation and obtain the coupling of said seal gasket element with said housing seats, - d) removing progressively said one or more temporary clamping elements (C0, C1, C2, C3; C4) to release sequentially successive parts of said seal gasket element and releasing progressively the surface of said sliding member and, - e) progressively introducing the parts freed in succession of said sliding member into said housing cavity to enable the seal gasket element to expand gradually radially through the effect of the spring-back, sealingly adhering by surface pressure to the inner surface of said housing cavity. - a0) obtaining, in the cylindrical part of the surface of said sliding member, housing seats for said reticular seal element, said housing seats being shaped as recesses that extend according to a closed reticulation distribution around said recirculation slots to contain and fix said reticular seal element, - a1) shaping these housing seats with sections suitable for retaining said reticular seal element, exerting a friction force that is greater than that arising from the free surface sliding of said reticular seal element with respect to the housing surface in which said member slides, in which for making said sealing gasket element: - a2) a precursor element of said seal gasket element is obtained from an elastoplastic material, by shaping said precursor element with a grid structure having a reticular shape corresponding to said housing seats, - b) positioning said precursor element around the recirculation slots for the resins of said sliding member at the housing seats, - c) exerting on said precursor element, by one or more temporary clamping and preliminary deformation elements (C0, C1, C2, C3; C4), a compression action for radial contraction and longitudinal adaptation that are suitable for pressure inserting, adapting by deformation to the shape of the housing seats and coupling by deformation said precursor element in one or more housing seats provided on said sliding member so as to apply by deformation and obtain the coupling of said seal gasket element with said housing seats, - d) removing progressively said one or more temporary clamping elements (C0, C1, C2, C3; C4) to release sequentially successive parts of said seal gasket element and releasing progressively the surface of said sliding member and, - e) progressively introducing the parts freed in succession of said sliding member into said housing cavity to enable the seal gasket element to expand gradually radially through the effect of the spring-back, sealingly adhering by surface pressure to the inner surface of said housing cavity.