AbstractWettability plays an important role in a number of industrial applications. Often it becomes desirable to control contact angles (wettability). For this purpose, two techniques for altering the contact angles of glass beads are described. These involve chemisorption of Silicones or Hexamethyldisilazane (HMDS) on glass surfaces.The results of measured contact angles on treated glass beads indicate that by carefully controlling the treating procedure, it is possible to obtain the desired wettability.