One. Scientific Foundations of Hollow Glass Microspheres one.1 Composition and Microstructure one.one.1 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, fifty-90%), alumin... https://demo.jcow.net/images/viewstory/88298