De-mold by pulling off the plaster impregnated cheesecloth and the alginate. The plaster will still be a bit soft allowing you to clean up any flashing or mold deformities. You can fill any holes with Spackle and use a plaster rasp to smooth the edges.
Figure 18. De-molding may require that you first pull apart the plaster shell to remove the casting. But often you get lucky by slipping your fingers between the plaster cast and the alginate and with a steady pull, removing the cast while leaving the entire mold in tact as this image shows.
Once you demold, there will almost also be a few areas requiring clean-up. You can do this with a sharp knife or a plaster rasp. But, once satisfied with the look, wait 48-hours before painting or sealing with a clear polyurethane matte coating.
Figure 18. De-molding may require that you first pull apart the plaster shell to remove the casting. But often you get lucky by slipping your fingers between the plaster cast and the alginate and with a steady pull, removing the cast while leaving the entire mold in tact as this image shows.
Figure 19. VIOLA! A beautiful face cast.