Levasil CC151 is an alkaline, aqueous dispersion of colloidal silica that is approximately 15% solids by weight. The silica dispersion is sterically stabilized and the amorphous silica particles carry a negative surface charge. The silica particles are discrete, have a smooth, spherical shape, and are present in a narrow particle size distribution. The particles have also been surface modified with an epoxy silane. “Hydroxyl number” for 2-pack systems; 0.45 mole OH/kg product. The physical appearance of the dispersion is a clear liquid, slightly more viscous than water. Levasil CC151 is produced for world-wide distribution.