The vacuum impregnation process seals internal leak paths to make it leak free and suitable for use. In the course of sealing castings against porosity, the parts would be processed through the following four stations:

1. Impregnation
The impregnation stage is the first part of the porosity sealing process. Air is evacuated from the porosity under dry vacuum and a liquid sealant is drawn into the porosity, filling any voids and leak paths.

2. Drain
Once the sealant has filled the porosity the components are rotated to drain excess sealant.

3. Cold Wash
After the excess sealant has been drained, the components are rotated under a wash water solution to remove any excess sealant from external component surfaces.

4. Hot Cure
Finally, a hot cure cycle is used which polymerises the sealant, turning it from a liquid state to a solid polymer, sealing porosity and leak paths within the component.