On doffer brushes and burnishing tools ... of the ones I have, the doffer brush is a little affair not much bigger than a flicker, but with long, deep, coarse-looking teeth. Great for picking up fibers off the drum carder to clean it. The burnishing tool is the same shape as, and maybe slightly larger than, a wool hand card, but with fine teeth (like my cotton carder's fine teeth) but fairly long besides -- same length as the doffer's I guess. I was told to hold the burnishing tool atop the carder as it was going (a PG supercarder) to temper the batt a bit -- push it into the teeth so you can get more in -- and also to help keep the drum carder's teeth sharp (burnished, thus the name). There's a brush-type attachment I've seen on some drum carders, but mine is definitely more a hand-card looking type of thing, from Patrick Green, it came with my PG Super Carder.
(posted by me this day on livejournal\spinningfiber)