A professional who operates pebble mill to grind emery, rouge, and other abrasives and separates them according to fineness by water suspension method. Respnsibilities include:

• Examines abrasive under microscope to determine grinding time required, and grinds abrasive in pebble mill.
• Turns valve to allow ground particles and water to flow into agitator tank.
• Presses button to start agitator which stirs particles into suspension.
• Stops machine and determines by microscopic examination when particles of particular grade have settled below tank outlet.
• Opens stopcock to allow particles remaining above the outlet to descend into vat.
• Repeats separation process for other grades, regrinding as required.