The Engineering of Duct Tape
696,502
Published 2024-05-21
Video summary
00:00 Titles/Introduction
Bill explains that duct tape was invented in the 1940s to seal ammunition boxes, but now is used to temporarily fix many things.
00:21 Duct tape on Apollo 13
Bill notes that duct tape was used to repair a carbon dioxide filter on the Apollo 13 Moon mission in 1970. The improved filter was needed because an explosion destroyed part of the life support system.
00:35 The basic functions of tape
Tape is designed to do three things: a) adhere with light pressure, b) stay in place, yet c) be removable.
00:53 Components of duct tape
By dissolving duct tape in the solvent toluene, Bill separates duct tape into its three components: plastic backing, adhesive, and cloth reinforcement.
01:32 Properties of Tape Adhesive
Bill contrasts the adhesives used in tape with glue to highlight the unique properties needed for tape adhesive. He shows that Elmer’s glue, a typical household adhesive, dries by evaporating solvent until it becomes solid. He notes that this would not work for duct tape. Instead, tape’s adhesive never hardens because it must adhere when pressure is applied (rather than dry to adhere like Elmer’s glue), hold tight, then let go when the tape is peeled from a surface.
02:11 Tackifier
Bill explains that the stickiness of duct tape comes from a substance called a tackifier, which is a substance that is sticky like syrup. He demonstrates that a tackifier alone isn’t enough for tape: a tackifier can affix something lightweight, but fails with heavy loads. This is unlike duct tape, which can hold at least a 5 pound/2.3 kilogram weight.
02:46 Viscoelasticity
Bill notes that the adhesive for tape is a tackifier mixed with a viscoelastic substance. A viscoelastic substance is a substance that can be, depending on the rate at which it is deformed, liquid-like, solid-like, and which can exhibit elastic behavior. He demonstrates this with a familiar viscoelastic substance: Silly Putty. He shows Silly Putty flowing, fracturing, and bouncing — that is, behaving like a liquid, a solid, and exhibiting elastic behavior.
03:46 Close up of tape being applied
A close up of a piece of tape being applied to a glass surface illustrates how tape’s adhesive displays liquid-like and solid-like behavior. When applied it behaves like a liquid: light pressure causes the adhesive to flow and “wets” (i.e., spreads over) the surface, which allows it to stick to a surface. Once applies the adhesive behaves like a solid to support weight and keep the tape in place.
04:13 Cloth reinforcement
Bill mentions that the weight is held up by the cloth reinforcement. He examines close up the cloth reinforcement used in tape.
04:51 Close up of tape peeling
Bill shows that when tape peels off a surface it exhibits elastic behavior, although sometimes some of the tape’s adhesive can stick to the surface. This is cohesive failure. When this happens the adhesive is behaving like a solid.
06:22 Why gaffer’s tape doesn’t leave residue
Bill explains how gaffers tape and sticky notes peel off a surface without leaving residue.
07:07 Release coating
Bill describes the silicone-based release coating on tape’s plastic backing, which allows it to be formed into a useful roll. This adjusts how much tape sticks to itself. If it sticks too tightly, a user could not remove the tape from the roll; if too loose, then the tape would telescope — he demonstrates the latter with a defective roll of tape.
08:37 Tape adhesive developed by the engineering method
Bill explain briefly that while chemistry is important to synthesize the adhesives, their development is done by the engineering method. The engineering method is described in his book The Things We Make (isbn 978-1728215754 hardcover / 978-1728280455 paper).
09:36 Rolling ball test
Bill demonstrates the rolling ball test to quantify the stickiness of a tape’s adhesive. This is one of many empirical methods used by engineers to engineer tape.
10:15 Where duct tape should not be used
Bill ends this video with a caution: Duct tape — surprisingly! — should never be used on ducts.
10:33 End Credits
All Comments (21)
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this feels like one of those really old 70s educational videos, perfectly scripted and produced to contain exactly the visual and information required to get a better understanding. no fluff, no bloat, just perfection.
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He's alive!
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Gonna tell my kids this is Technology Connections' father.
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What I love about Bill's videos is there is no fat. Its straight to fascinating, factual content. Really is one of the few channels i virtually stop what i am doing whenever a new video gets released!
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7:46 my whole life described perfectly: setting the balance between too tacky and not tacky enough
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Your videos are the main reason I chose to become an electrical engineer. The magnetron, quartz clock, atomic clock, transistor, accelerometer, CCD, and harmonic analyzer videos, really inspired 11 year old me to go down the path of engineering. I am now halfway through a degree in Electrical engineering, with a specialization in systems and controls. I am incredibly grateful for these videos, and all the potential engineers you’ve created.
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"as we've just seen, controlling the stickiness of tape is of utmost importance" You know you've created a valuable YouTube channel when you can say a sentence like that unironically and it becomes an aha moment for the whole audience. Well done
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I remember back when I was in high school watching these videos in awe and thought they were excellent material. Fast-forward a few years later, I’m attending UIUC as an engineering student and I ran across you on one of the bus lines. Forever grateful for that conversation we had, and glad you’re making more videos again!
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Makes me proud to be an engineer. We may not understand everything, but we find a way to make it work.
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Well I’m genuinely happy knowing this guy is still alive, for me this is one of the OG educators on the internet
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this video is so thrilling, i cant explain it. Bill's presentation is similar to what we were watching in school on VHS tapes. Peak of educational presentation - no other youtuber compares.
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I'm a mechanical engineer turned dentist, and Holy crap this video is so far up my alley. Obvious why it's interesting to an engineer, but as a dentist there is so much engineering that goes into designing all the composite resins, acrylics, etc we use for fillings and cementing crowns, repairing dentures, etc etc. Great video!
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As the old adage states, “if it shouldn’t move, use duct tape, if it should move, use WD40” I think we know what the next companion video should be. Awesome to see you back, always incredibly informative
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I'm a grown man, but if you adopt me, I'd be happy to listen to every single story you have to tell.
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Hey it's engineerguy! I bought your book what must have been a decade ago. It's a real pleasure to see you still releasing fresh videos.
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This video is so high quality and well put it made me spend 11 minutes glued to the screen.
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I graduated in Materials Engineering in the 80's and I can say that this single 10 minute video is worth about a semester of courses.
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That parting dad joke, or should I say, engineer joke, was the cherry on top. Quality content as always!
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I was so excited when I saw a new upload, welcome back! The ending of this was comedy gold, its almost like they avoided saying "Duct" in the list.
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"don't use it on a duct" is very true. Once we tried to fix a temporary air bag duct as it eventually disintegrated in in use with duct tape and the tape held even less than the bag when air was pushed through with enough force. Constant motion from turbulent air just detached the tape and small dust particles in air made sure lost stickiness.
