Close mold resin infusion
This is where closed-mold manufacturing comes into play. The process is resin infusion and it is already in use by leading-edge boatbuilders. Resin infusion, also called vacuum infusion, is the ticket to modern fiberglass boat construction. The show begins with a mold cavity containing the dry fiberglass laminates, as well as Kevlar or carbon fiber if used. The dry laminates are covered with a special bag material, which is then sealed to the mold flange. Flow media is installed that serves as a conduit to direct the resin that will enter the mold via a series of tubes connected to a manifold. A hull is a complex part with a dozen or more lay-up schedules and several different core types, and these factors are taken into consideration because they affect resin flow.
Accordingly, there can be 5 or more resin inlets and these are monitored during the process as the resin is pulled through the mold under vacuum. When the valves on the manifold are opened, the catalyzed resin flows freely, wetting the laminates under the bag. There is no sound and no smell as the resin flows through the tubes. However, it is fascinating to watch the laminates turn from white to red as the resin is vacuumed through; it actually resembles blood leaking out from underneath a bandage.