Went back to my 8 inch round brush after trying that fancy flat wire one, night and day difference on a 40 year old flue
Picked up one of those flat wire brushes at a supply shop in Albany last month thinking it would scrub faster on a badly glazed flue off a wood stove. Used it on two jobs and it just smeared the creosote around instead of lifting it, and the flat head kept grabbing on the damper frame. Went back to my old 8 inch round poly brush on a set of rods and the same flue came clean in about 20 minutes with way less mess on the drop cloth. The round brush gets all the way around the tile and the flat one only really hits two sides. Anyone else find flat brushes are only good for certain flues, or did I just use it wrong?
Did you check the flue size before buying that flat one, because on a 6 inch liner you might have been fighting the wrong shape the whole time? Round makes sense on square tile but I never see guys talk about matching brush shape to the actual flue, they just grab whatever is on the shelf.