A vacuum is applied between the sheet and the lay-up. The entrapped air is mechanically workded out of the lay-up and removed by the vacuum, and the part is cured with temperature, pressure, and time. Also called bag molding. VENT - A small hole or shallow channel in a mold that allows air or gas to exit as the molding material enters. The tendency of a material to resist flow.
Porosity is an aggregation of microvoids.
Voids are essentially incapable of transmitting structural stresses or nonradiative energy fields. The condition of an impregnated roving or yarn in which substantially all voids between the sized strands and filaments are filled with resin. The period of time during which a liquid resin or adhesive, after mixing with catalyst, solvent, or other compounding ingredients, remains usable. Also occurs in vacuum bag molding when the bag is improperly placed, causing a crease. These fiberglass 101 how to pages have moved to their own home.