Polytek Poly Fiber II (1 Gal) Add to polyurethane liquid rubbers to thicken for brush-on application or to liquid polyurethane plastics to thicken for making mold shells or layup castings The level of thickening can be easily controlled to make thins gels to thicker pastes Great for use with Poly 74-Series rubbers to make them brushable Can also be used to thicken Polygel rubbers further