An International Correspondence Schools instruction paper (Serial 472) on burr picking, the first mechanical operation applied to scoured and dried wool to remove burrs, twigs and other vegetable matter before carding. It describes the Parkhurst, Sargent multiplex, single burr-cylinder and Goddard (Curtis and Marble) burr pickers, covering feed-rolls, picking and burr cylinders, burr guards, brushes, beaters, blowers, drives, speeds and capacities. It also gives burr wire types and advice on setting, cleaning, oiling, safety and the gauze room.