Tried the plastic sheet trick on a nasty flue in an old house in Salem last week
Had a 1920s colonial in Salem with a flue that was caked so bad my usual 6 inch brush barely made a dent, and I was about to tell the homeowner it needed two trips. I taped a sheet of plastic over the firebox opening, cut a small slit for the rods, and the draft pulled all the loose soot straight up the chimney instead of into the living room, cleaned the whole thing in one visit. Anyone else use the plastic trick, or do you just bring a bigger shop vac and deal with the mess?
Problem with just taping the plastic is you still get soot falling back down when you pull the rods out, so what I started doing is cutting the slit as tight as possible and then taping a second smaller sheet over it. That way the rods slide through but the seal stays mostly closed the whole time.