PVC Foaming Shoes Additives are a new generation of products that can be used to produce a variety of foamed products. The main component of these products is microspheres, which are tiny spheres made from a variety of materials including glass, ceramic or polymer. Microspheres have a very high surface area to volume ratio, which makes them ideal for use in foaming applications. When mixed with a suitable blowing agent, microspheres can be used to produce lightweight foams with excellent physical and mechanical properties.