Methods and apparatuses are disclosed for applying activatable melt flowable materials to substrates made from synthetic materials. The methods are concerned with formation of appropriate flowable materials, control over the manner in which the flowable materials are applied, treatment of the substrates prior to application of the flowable materials and the selection of the optimum combination of materials for the substrates and the flowable materials. The methods may be particularly suited for applying flowable materials to surfaces to produce components found in automotive, aerospace including trucks, busses and tractors and marine vehicles.