Abstract: A process and apparatus for manufacturing a blowable glass fiber insulation product is disclosed. The product (104) resulting from the process and apparatus is also disclosed. This process includes the steps of cutting unbonded glass fiber matting (102) and lengths of twisted glass fiber yarn (101) raw material into pre-determined relatively large size pieces. The pieces are mixed together and the mixture is fluffed to decrease its density. The mixture is then hammermilled into relatively smaller size pieces suitable for use as blowable insulation. In accordance with the apparatus according to this invention, a cutter (20) cuts glass fiber matting (102) and lengths of twisted glass fiber yarn (101) into relatively large size pieces which are mixed and then fluffed and further cut in a fluffer (40). A hammermill (60) is used for reducing the mixture into relatively smaller size pieces suitable for use as blowable insulation.