Duct Tape... Uses and Abuses
Loving duct tape means never having to say you're sorry... when it fails!
I was, at one point in my career, a duct tape addict. I would lash together lumber, repair hammers, fix my trusty wooden tool box... ad infinitum. Then, in my travels through thousands of homes, I came to see the weakness in duct tape as some repairs done with it days, weeks or months before began to fail. The weakness in duct tape's armor is due to three factors... poor adhesive quality, heat and ultraviolet light.
The adhesive used on duct tape is tenacious. If you've ever torn off a piece and had it touch itself, you know the meaning of sticky! Straight to the garbage can for that strip, yessirree. But as strong as this adhesive is, it is not really permanent like a setting-type adhesive. And some "bargain basement" duct tapes are not worthy enough to wrap fish!
Heat can soften duct tape adhesive, making it lose strength. If there is weight or stress on the repair, this softening can cause the tape to slip and the joint or attachment to fail. This can be prevented by use of a secondary fastener such as a clamp or strap. A classic example of this faux pas happened to a customer of mine a number of years ago...
A repair person was called in to troubleshoot and repair a dryer vent line which no longer blew to the outside. All visible connections seemed to be OK, so he had to cut the wall open behind the dryer to assess the situation. What he found was a failed junction between two pieces of plastic duct hose connected together at eye level by a 12" long piece of 4" round aluminum ducting with duct tape alone as the fastener!
I suppose he thought that the last guy just didn't use enough tape, so he wrapped the connection in what appeared to be half a roll of duct tape... with no other fasteners... and closed the wall back up. It took about six months for the repair to fail. I'm amazed it lasted that long! The heat from the clothes dryer caused the connections to separate as the tape softened, until the two sections of pipe totally separated from each other within the newly repaired and painted wall. Darn..
The repair guy, of course, has never been heard from again.
I don't have the trust in duct tape I once had. So as a rule, unless I am looking for a temporary repair, I always find a way to supplement the strength and air-sealing properties of duct tape with a more permanent fastener!
Using duct tape outside...
No, I didn't forget about the effect of ultraviolet light on duct tape, Randy. If you don't know Randy, he is the editor of the Feather River Canyon News, and a while back he reminded me of the problems in using duct tape outside for anything but temporary repairs... especially when exposed to the sun. He likened it to a "a powder-coated set of threads with dried up adhesive." Enough said!
However, I understand that there are some newer duct tapes that are UV-resistant, making them more suitable for outdoor use. For example, both Gorilla Tape and Scotch® All-Weather Tape are outdoor-friendly. Be sure to read the label before purchasing and duct tape for outdoor use.