The other day I received a press release from Shurtape titled “The Secret of Making Duct Tape”. How could I not open something like that?
According to the press release, lamination is the most common method for manufacturing duct tape, and involves the continuous combination of film, cloth and adhesive. Laminated duct tapes are flexible and conform to a variety of surfaces—making them best for use on curved and uneven surfaces. The other way to make tape is by co-extrusion, which involves melding polyethylene, cloth, and adhesive in a single high-temperature process. Co-extruded tape is thinner, stronger, and lays flatter than laminated tape, and won’t delaminate when subject to stress and weather.
Co-extruded tape can be identified by the dimpled appearance of its surface; with laminated tape you’ll see the texture of the fiber it contains. Shurtape is one of two U.S. manufacturers of duct tape that use the co-extrusion process for at least some of its products. An infographic they produced on choosing tape can be seen below.
Not wanting to take the manufacturer’s word for how great co-extruded tape is, I searched the web and found a number of interesting items on the subject, including a presentation by the Missouri State Highway Patrol Crime Lab on how to identify different types of tape, a video of the production process (see below), and a 2013 test of various brands and types of duct tape by Doug Mahoney—a carpenter who occasionally writes for Tools of the Trade. He performed an impressive series of tests, including ones for strength, adhesion, and resistance to weather.
Doug’s overall favorite for general use was Duck Max Strength, which he described as “best overall because of its strong adhesive and high material strength. Though it still manages to be flexible enough to wrap around corners and is easy to tear in a clean, straight line.” His favorite for long-term exterior use is Sticky Ass Tape, which he said is “harder to rip and isn't as flexible, but it's very effective for outdoor uses like temporarily fixing a hole in your gutter”. The story includes comments on several other brands and a detailed description of how duct tape is made.