An auto windshield is comprised of three separate layers of glass that have been laminated together. When a rock from the road hits an auto windshield, it breeches the top layer of glass causing an air gap between the plastic middle layer and the top (outer) layer. Debris and glass shards from the top layer of glass are propelled inward. Windshield repair attempts to clear away as much of the debris as is possible and then fill these air gaps by injecting a clear acrylic resin into the damaged area. Alternating vacuum and pressure cycles are used to continuously remove air and debris trapped in the damage area so that the resin can flow further and further into the break, eventually filling it.