Vacuum bag

The process of covering a composite layup with plastic sheeting (figuratively, a bag) that is sealed around the edge and using a vacuum pump to remove all air from the inside. This compresses the plastic sheet around the composite, squeezing out the excess resin and leaving a compact, light layup. Vacuum bagging produces a very good quality layup; it would take a lot of skill to produce a layup of equal quality without vacuum bagging.