SOLAREZ 3M Microballoons Solarez 3M Microballoons These microscopic glass spheres added to resin systems make a lightweight, easy-to-sand putty for minor surface filling of cracks, holes, etc. Used in lower concentrations, they "extend" resin by fluffing it up and reduce shrinkage, they also have very good compressive strength. They differ from "Q-Cell" in that microbaloons are more consistent in size.