My buddy runs a chimney sweep outfit up in Tacoma and he had the SAME thing happen. He was stubborn about it too, swore by the hand brush for years because thats how his old boss trained him. Then he got a nasty 3rd degree glaze job on a wood stove and the wire brush just polished it shiny instead of taking it off. He borrowed a rotary setup from another sweep and had the whole thing done before lunch. Now he wont even load the manual brush on the truck for creosote calls. Saves his shoulders too, he was complaining about his rotator cuff for months before that.