Resin Casting Equipment

The pressure pot is a chamber in which the molds sit while surrounded by compressed air. The pressure of the air at 80 PSI squeezes the air bubbles into suspension while the liquid resin turns into a solid casting, eliminating the problems of air bubbles in the finished part.

The molds are placed into the pressure pot through the opening on top. Liquid resin is poured into the molds either before or after they are placed into the pot. The oval lid is tipped so that it will fit through the opening, lowered down, then twisted and raised up so as to create a seal. Compressed air is then allowed into the pot through a valve, forcing the lid up against the bottom of the opening ring. The black part of the lid is a rubber gasket.

The compressed air comes from a compressor into the pot out through the air diffuser—shown in cutaway view—circulating the air around the bottom.

After the resin has hardened, another valve is opened to release the air to the outside atmosphere, and the lid is removed. The molds are retrieved and opened up.

The vacuum chamber is used to remove the air—or deair—the silicone rubber used for making the molds. Once the air is eliminated the liquid rubber can be safely poured over the master sculpture without danger of any bubbles ending up in the finished mold.

The lid is acrylic plastic, 1" (2.5cm) thick, through which the operator can see how the deairing process is progressing. Between the lid and the drum is a ring of crepe foam, which serves to create a seal when the lid is sucked down by the vacuum. The steel drum consists of a lower storage chamber, and an upper working chamber. The vacuum pump draws air out of the storage chamber, through the valves and into the pump.

The bucket of rubber is placed into the working chamber, and by opening one valve, the air in the upper chamber is partially sucked out by the vacuum in the lower chamber. The pump continues to run until the upper working chamber reaches full vacuum.

While under vacuum the rubber mix grows in size as the air bubbles increase, finally collapsing when full vacuum is reached and the air bubbles break on the surface. By opening the lowest valve, the outside air is allowed back into the upper chamber, releasing the suction on the lid and allowing the operator to lift it and remove the bucket of rubber.

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