The closed mold Vacuum Infusion Process (VIP) is attracting a growing following from spray-up fabricators wanting to meet the EPA's MACT (Maximum Achievable Control Technology) standards for hazardous air pollutant emissions, which took effect in 2006.
VIP, a generic term for any molding process that uses vacuum as the driving force for saturating a laminate, is a closed mold system with the laminate sealed prior to and during saturation. It is therefore cleaner, safer and more environmentally friendly than open molding processes. It also uses less resin and labor than spray-up, though resins for VIP cost somewhat more. To make a vacuum infused composite, dry fiberglass reinforcement is positioned on the mold surface. If the laminate is a sandwich construction, the core is added, along with additional top laminate. Once the laminate stack is complete it is sealed and vacuum applied to evacuate the air and compress the fibers. Resin is then allowed into the sealed cavity. The vacuum draws resin through the fibers, allowing just enough resin in to fill the fiber reinforcement.