Duct Tape Isn't for Ducts, after All
“We tried as many different kinds of duct sealants as we could get our hands on,” says Sherman, of Berkeley Lab’s Environmental Energy Technologies Division. “Only duct tape failed . . . often quite catastrophically.”
I shouldn't be surprised. A few months ago I tried using duct tape to seal the exhaust duct from my dryer when it kept coming apart. It didn't work as a sealant but it did succeed at attaching both parts of the duct to the wall.