A professional who tends equipment that cooks animal fat, and filters and bleaches oil. Respnsibilities include:

• Cooks fat in steam-jacketed kettle.
• Turns valve to admit rendered oil to agitator tank.
• Starts agitator, and turns valve to heat tank.
• Dumps specified amount of fuller's earth (bleaching agent) into tank.
• Turns valves to transfer oil through filter drums into storage tank.
• May add preservative solution to lard in mixing tank and press button to blend ingredients.
• May be designated according to material handled as Oleo-Hasher-And-Renderer (oils & grease).