In a typical hand lay-up, reinforcements are laid into a mold and manually wet out using brushes, rollers, or through other means. An improvement on that method is to use a vacuum bag to suck excess resin out of the laminate. Vacuum bagging greatly improves the fiber-to-resin ratio, and results in a stronger and lighter product. VIP requires a lot of experience in this area and uses many of the same principles. Vacuum infusion builds upon these principles, providing further improvements to the lamination process.