I have two stoves in the house both Vermont Castings and a Lopi in the garage. Metal 6" flue pipe on all. I clean my chimney each year but don't use a brush. I go up on the roof and drop my cleaning appliance down and raise it up and down 20-30 times. My cleaning appliance is an old pair of jeans where I cut the leg off and filled it with smooth (rounded) river stoves. I tie wrapped the ends and attached a rope. Doesn't scratch and is smooth but still rubs the soot off the sides. I'll post a picture one of these days. FYI - tried a cat once but the noise was horrible - just kidding.