General Plastics typically uses multiple pour-in-place processes when filling nuclear packaging impact limiters or over packs with LAST-A-FOAM ® FR-3700 series of material. It may be necessary to conduct two or three pour increments to fill a cavity of just a few cubic feet in some units, while other larger units demand more than a dozen pour increments of 500 lbs. per pour to fill more than 450 ft³ for a single unit. The advantages of this multiple-pour process are that it controls the exothermic heat, reduces the internal pressures produced throughout the foam expansion and limits density variation throughout the filled unit. This process results in knit lines or pour layer boundaries between the layers of foam.