molding compounds where they make good penetration of the glass fibers extremely difficult u201d to the contrary this invention uses thixotropes in smc to make light weight parts moldable at low pressures among the thixotropes useful in the composition used to make the molded part of this invention are the preferred thixotrope used in the process of this invention is fumed silica the fumed silica is available from degussa corporation ridgefield park n j as aerosil 200 hydrophilic fumed silica having a bet surface area of 200 u00b1 25 m 2 g as measured by din 66131 from cabot corporation boston mass as cab o sil m5 with similar characteristics or from wacker chemie adrian mich as hdk fumed silica in the molding industry as described in the asm international engineered materials handbook u201c composites u201d thickeners include calcium and magnesium oxides and hydroxides they initiate the reaction that transforms the mixture of smc ingredients into a handleable reproducible molding material usually 0 25 to 3 5 of the smc formulation is thickener it is the final ingredient added to the resin mix and it begins the chemical thickening process immediately thickening agents useful in this invention are alkaline earth oxides or alkaline earth hydroxides magnesium oxide is the preferred thickening agent optionally fillers may be used in this invention useful fillers include calcium carbonate kaolin clays and hollow glass spheres the preferred filler is calcium carbonate maleic anhydride 599 parts 6 11 moles and propylene glycol 510 parts 6 71 moles were reacted at 200 u00b0 c in the presence of hydroquinone until an acid value of 30 was reached the.