Lay dry fiber into a mold, seal it under a plastic film, and let the atmosphere do the work. Vacuum infusion turns the 101 kPa of pressure sitting on top of all of us into a precision manufacturing tool. The setup is deceptively simple. Dry reinforcement (glass, carbon, or aramid) is stacked in the mold, then covered with a stack of consumables: peel ply, a distribution mesh, spiral feed tubing, and a vacuum bag sealed to the tool with tacky tape. A pump evacuates the air. Once the bag pulls down hard and holds vacuum, a feed line is opened and degassed resin is pulled through the preform by the pressure differential alone. That flow is not random. It obeys Darcy’s law: • Q = (k·A/μ)·(ΔP/L) • k is the permeability of the fiber stack • μ is the resin viscosity • ΔP is the pressure drop driving the front This is why infusion resins are formulated with low viscosity and long pot life. The resin has to travel the full length of the part before it gels, and the engineer controls tha...