Next comes applying sealant tape between the two mold halves and bolting them together. Then a tiny hole is drilled in the mold. A vacuum pump sucks the air out of the chamber. Users pour resin into the resin reservoir and open the cocks. Due to atmospheric pressure, the resin flows into the mold through tubes in the rotating shaft that holds the mold. The material’s viscosity keeps it from escaping out of the tiny hole (which lets any air between the bladder and the mold escape).