Hollow Glass Microspheres (K20, Density 0.20 g/cc)

Hollow glass microspheres grade K20 offer a true density of 0.20 g/cc, providing the practical balance point between maximum weight reduction and processability in medium-pressure composite applications. With thicker glass walls than the ultra-light K1 grade, K20 microspheres exhibit significantly higher isostatic crush strength (typically 1000–2000 psi), enabling their use in hand lay-up laminates, closed-mold RTM, vacuum infusion, and SMC/BMC compression molding without significant sphere breakage.

In a filled resin system, K20 microspheres at 20 vol% reduce composite density by approximately 15–20% compared to an unfilled system, while adding minimal viscosity. The spherical geometry of hollow glass microspheres produces lower compound viscosity than equivalent-volume irregular mineral fillers such as CaCO3 or talc, maintaining good processability even at high volume fraction loadings.

K20 microspheres are widely used in FRP boat hulls and deck structures (weight reduction for performance or fuel economy), automotive structural composites, aerospace fairing and non-structural panels, and wherever a combination of low density, low resin shrinkage, and good surface quality is required. The glass chemistry is compatible with all thermoset resin systems. Surface modification with silane coupling agents is available to improve adhesion to the resin matrix.