SIP's are most often manufactured in a traditional factory. Processing equipment is used to regulate pressures and heat in a uniform and consistent manner. There are two main processing methods which correspond to the materials used for the SIP core. When manufacturing a panel with a polystyrene core both pressure and heat are required to ensure the bonding glue has penetrated and set completely. Although a number of variations exist, in general, the foam core is first covered with an adhesive and the skin is set in place. The three pieces are set into a large clamping device and pressure and heat are applied. The three pieces must stay in the clamping device until the glue has cured.