1. Scientific Foundations of Hollow Glass Microspheres 1.one Composition and Microstructure 1.1.one Chemical Composition: Borosilicate Dominance Hollow glass microspheres (HGMs) are mostly made up of borosilicate glass, a material renowned for its very low thermal expansion coefficient and chemical inertness. The chemical make-up typically features silica (SiO₂, 50-90%), alumina (Al₂O₃, https://demo.jcow.net/images/viewstory/88298