Heard a guy at the supply house say wire brushes wreck flues and now I'm second-guessing everything

I was picking up some 8-inch liner last Tuesday and this older sweep was telling the counter guy that wire brushes scratch the terra cotta and cause more buildup over time. He claimed poly brushes are the only safe bet for clay liners. Anyone here actually switch away from wire and notice a difference?

2 comments

2 Comments

spencerl321mo ago

Good question because I've heard the same thing from a few old timers but never really tested it myself. Have you ever pulled a brush out and actually looked at the clay after a few passes to see if you're leaving visible scratches? Pretty sure the real issue is whether you're using a brush that's way too aggressive for the liner, like a heavy gauge steel wire on old soft terra cotta. Seems like it would depend a lot on how much soot and glaze is already on there too, you know?

wren6521mo ago

Always run your hand over a piece of old terra cotta before you start. Some of that stuff is so soft and crumbly it feels like sandstone, and a stiff wire brush will absolutely chew it up. I switched to a poly brush on a really old flue a few years back, and it still got the heavy creosote off without leaving those deep parallel scratches you see with metal. Anything that smooths out the glaze and turns the clay surface rough is just giving soot more places to grip onto.