Duct Tape Is Amazing, Just Not for Sealing Ducts

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Of all the inventions crafted through the ingenuity of man, duct tape may be the most indispensable.

Have a wart that you want eradicated? Duct tape. Need a bag of chips sealed? Duct tape. Want to get in a punishing workout? Duct tape. Procrastinated on your Halloween costume? Duct tape. Is the fender of your lunar rover damaged? Duct tape.

481px-Duct_tape_apollo17.jpgBut despite all the amazing things duct tape can do, there's one surprising thing that it can't do: seal ducts.

That counter-intuitive tidbit of information was uncovered fifteen years ago in the summer of 1998. Max Sherman, a physicist working at Lawrence Berkeley National Laboratory, led a study testing the effectiveness of a variety of duct-sealing materials. He and his partner, Iain Walker, set up a wall of joined ducts, all with leaky joints, and sealed each joint one by one with thirty-three different sealants. The contestants included clear plastic tape, foil-backed tape, mastic (a high grade construction adhesive), injected aerosol sealant, and many varieties of duct tape. All were put through both a stress test -- where the ducts were heated to temperatures up to 187 degrees Fahrenheit -- and an aging test -- in which hot and cold temperatures were flushed through the ducts and fluctuated every five minutes for up to three months. A sealant was failed if the joint leaked ten percent of the air it leaked before being sealed.

"Of all the things we tested, only duct tape failed. It failed reliably and often quite catastrophically," Sherman said in1998.

Before your devilish mind wanders too far with Sherman's use of the word "catastrophically," no duct tapes burst into flame. All they did was fall off, sometimes after just a few days, which is sort of dramatic as far as duct sealing goes, I suppose. 

Since the study, not much has changed: duct tape is still useless for sealing ducts. A lot changed for Sherman, however. He became a "duct tape hero" in the eyes of his children, but a duct tape villain to groups who idolize the sticky adhesive -- yes, they exist. Early after the study's release, Sherman's wife was loosely concerned over her husband's notoriety.

"She has forbidden me from opening any packages sealed with duct tape, meeting with duct tape manufacturers unchaperoned, or having anything to do with the state of Montana," Sherman joked.

Oh, and in case you were wondering, the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) recommends fire-resistant tapes with long lasting adhesives for sealing ducts.

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