High Quality Content by WIKIPEDIA articles! A vacuum bag is a bag made of strong rubber-coated fabric or polymer film, open at one end, and used to bond or laminate materials. In some applications the bag encloses the entire material, or in other applications a mold is used to form one face of the laminate with the bag being single sided to seal the outer face of the laminate to the mold. The open end is sealed, and air is drawn out with a vacuum pump. As a result, uniform pressure approaching one atmosphere is applied to the surfaces of the object inside the bag, holding parts together while the adhesive cures.