synthetic materials having a relatively highly elastic or tough surface layers layers of plastic sheets 14 and non woven fiber fabrics 12 which contain no binder bonding agent agglutinant or cement are alternately placed on top of one another and then compressed in a compression mold 15 under heat by means of a compression molding plug 16 through the number thickness sequence selection of material or the like of the layer the characteristics of the pre finished plates can be predetermined and the finished sealing element obtains qualities that can be adjusted to the respective case of application a structure according to fig1 11 can be achieved for example through thicker fiber free top layers and through decreased proportion in fiber volume in the center compared to the remaining cross section of the sealing element whereby said structure ensures on one hand an excellent damping quality of the sealing element while having sufficient rigidity and it ensures on the other hand that no near surface fiber breaks occur with subsequent expansions of cracks caused by the compressive impact stress on the surface according to fig8 fabrication of essentially strip shaped semi finished materials may be performed by continuous compression molding in a double belt press 17 whereby a plastic sheet 14 and a piece of fiber fabric 12.