Fumed silica is mainly used in unsaturated polyester to make resin gel coats and putties. Almost all thixotropic agents used in resin gel coats are fumed silica. fumed silica can make the product much more uniform and reduce shrinkage. It is more in line with the design requirements; on the other hand, because the fumed silica increase the thixotropy, it can reduce the flow and dripping of resin, reduce the waste of resin.