Making A Giant Zipper To Explain How They Work

0:00 (zipper whirring)- How does a zipper actually work?

0:03 Like try to push down on a zipper from above and it probably won't budge,

0:08 but if you just use the pull tab, suddenly it's buttery smooth.

0:11 So how does it do this?

0:12 We've made more zippers than there are stars in the Milky Way.

0:16 You probably used one 10 times today without even noticing,

0:19 except the only time you do is when one breaks.

0:22 I'll show you what to do when this happens,

0:24 but what is actually going on inside this thing?

0:27 I mean, obviously the teeth come together inside the slider,

0:30 but it turns out there is a surprising amount of engineering to this thing.

0:33 All of this is too small to see on a real zipper, which is why we made this one.

0:39 This is a video about the surprising genius of zippers.

0:45 What is that?

0:46 This is a device that basically started it all.

0:50 The idea was just to take a bunch of hooks and eyes

0:54 and try to put them together in some fashion to make them quote,

0:58 "automatic", unquote.

0:59 [Gregor] The hooks seemed very sharp,

1:00 like I don't think I'd want this on my fly.

1:02 No, no.

1:03 Oh, definitely not there.

1:04 (Robert laughing)- By the 1800s, clothes were typically fastened using laces,

1:09 buttons, brooches, and hooks and eyes.

1:12 These got the job done, but they all shared the same flaw.

1:15 If you had a series of these fasteners on a piece of clothing,

1:18 well, you have to close them one by one.

1:20 Most people were satisfied with the state of affairs, but one man,

1:24 American engineer, Whitcomb Judson, thought the world deserved something better.

1:28 The idea, primarily,

1:30 it appears to be that he would put them in shoes and people who

1:33 had to lace up would be able to do it in one quick motion.

1:37 So that was the device that he had in mind, and it didn't work.

1:44 Judson was a pretty bad inventor.

1:46 Most of his patents had never gotten much traction, but he was a great salesman.

1:51 In 1893 at the Chicago World's Fair,

1:54 he presented this fastening device as the next big thing,

1:57 claiming that in no time at all this would replace buttons and laces,

2:01 and not just on shoes, but on all sorts of garments.

2:04 A few wealthy investors actually believed it.

2:06 So with their backing, the Universal Fastener Company was born.

2:11 A decade later, the company managed to carve out a small niche,

2:14 primarily selling its fasteners for women's skirts.

2:17 "A pull and its done!" said their ads, but that was a lie.

2:21 Judson's fastener design was a mess.

2:23 It jammed constantly.

2:25 And because it was delicate and made from rust prone steel,

2:28 it actually had to be removed from the garment before you could wash it.

2:32 So literally unsewn from your skirt.

2:35 Moreover, if a single hook and eye were out of place,

2:38 the whole fastener became unstable,

2:40 so simply bend over and the whole thing could pop open.

2:44 Naturally, the Universal Fastener Company had very few repeat customers,

2:48 and they fell into debt.

2:51 But in 1906, a new engineer joined the team,

2:55 25-year-old Gideon Sundback, who had just moved to the US from Sweden.

2:59 Why does someone like Gideon Sundback with a good

3:02 degree in electrical engineering decide to join this failing company?

3:07 Well, it's a great story.

3:09 [Gregor] See, one of the managers

3:11 at the company had-- An absolutely drop-dead gorgeous daughter.

3:15 (Gregor chuckles) And that daughter came into the eye of Gideon Sundback,

3:21 and he was completely smitten.

3:22 So he ends up working for the fastener manufacturer so

3:27 that he can cozy up to that daughter and they marry.

3:31 [Gregor] For the next few years,

3:32 Sundback made minor improvements to Judson's hook and eye design,

3:36 but none were ever enough to make the product truly functional.

3:39 Then soon after giving birth to a daughter, his wife Elvira, fell ill and died.

3:46 [Robert] And Sundback was absolutely devastated.

3:49 So the romantic tale is that he threw himself into his work

3:53 at that point out of fighting the grief from the loss of his wife.

3:58 This dark period in his life led to a major breakthrough.

4:03 Sundback realized that this (paper crinkling) was never gonna work.

4:07 So after years of tinkering, he submitted a patent of his own.

4:11 This is a patent from 1914, but if you take a look,

4:15 it is nearly identical to a zipper from today.

4:19 Sundback's modern zipper starts with two rows of teeth,

4:23 and the teeth are shaped so that they're wider

4:26 at the end than the opening on the other side.

4:29 So if you try to push them together, it's pretty hard.

4:33 Now, this is especially true on a real

4:35 size zipper where it's practically impossible.

4:39 But if I add this slider to the bottom and try pulling on the pull tab here,

4:50 suddenly it's effortless.

4:52 So how does it do it?

4:54 Well, I can remove the cover from the slider

4:56 to reveal that it's just a Y-shaped cavity.

5:00 That's it.

5:01 See, as you zip up, the Y-shaped cavity

5:04 tilts the teeth at just the right angle so

5:07 that the tooth has enough space to slot

5:10 into its groove without bumping into the tooth above.

5:14 And as you zip down,

5:16 this wedge shaped piece separates the teeth, allowing you to unzip.

5:22 This results in one awkward design quirk.

5:24 At the top, no zipper is ever fully zipped up because the wedge is always there.

5:29 It has to remain between the teeth.

5:31 Now, Sundback's original design was a little different to this big guy.

5:35 It sported rectangular teeth with a bump on the top called the nib,

5:39 and an equivalently shaped indent on the bottom called the scoop.

5:43 That way, when the teeth would align,

5:44 each nib would fit neatly into its neighbor's scoop,

5:47 forming a strong connection.

5:50 But there was a problem, even though Sundback had a new design and a patent,

5:54 manufacturing a zipper like this in the 1910s was very impractical.

5:59 Each of the tiny teeth needed to be precisely shaped for the fastener to work,

6:03 but at the time, there were simply no tools around that could do this reliably.

6:08 So he had to come up with some extraordinarily clever machineries that allowed

6:14 them to automate the production of the zipper from the very beginning.

6:18 Sundback's machine worked like this.

6:19 It took Y-shaped wire made from a nickel alloy as an input.

6:23 First, it sliced pieces off the wire to serve as individual teeth,

6:28 and then it stamped the scoop and nib into each tooth.

6:32 Finally, the machine would clamp the two arms of the Y-shape

6:35 together onto a piece of fabric called the tape.

6:38 This tape held all the teeth in place, and it was the part of the zipper

6:41 that would later get stitched onto clothes and other products.

6:45 Sundback's machines worked wonders.

6:48 Even in their earliest forms,

6:49 they could already make 150 meters of zippers per day,

6:54 and these zippers were incredibly strong.

6:56 That's because for a tooth to become unpaired,

6:59 it needs to get some distance between itself,

7:01 and its neighbors, enough for the nibs on either side to pop out.

7:04 But since the machines spaced the teeth so precisely,

7:08 there was simply no room for that to happen.

7:10 Now, you might think you could just

7:11 stretch the zipper vertically to separate the teeth,

7:14 but the zipper tape itself is made from strong inelastic fabric.

7:17 So even if the garment itself is stretchy,

7:20 the teeth are connected to the tape which is designed not to stretch,

7:23 so they won't come loose.

7:25 But there is a way for this mechanism to fail.

7:27 If even a single tooth falls off, well,

7:30 then its neighbors have enough space to come loose,

7:32 and then their neighbors come loose,

7:34 and this causes a cascading effect, and the whole zipper pops open.

7:39 This isn't something you had to worry about with buttons,

7:41 which can only fail one at a time.

7:44 But even with this flaw,

7:45 Sundback's employers thought this patent was a gold mine.

7:49 So the Universal Fastener Company decided

7:50 to launch the product under their new name, 'The Hookless Hooker'.

7:55 They abandoned that name pretty quickly and decided

7:57 to call it 'The Hookless Fastener' instead.

7:59 This new fastener was a successful product, but not a mainstream one.

8:03 Its first applications were pretty niche.

8:05 You'd find it on money belts, essentially the fanny packs of the 1910s,

8:09 as well as tobacco pouches and rubber boots.

8:12 Now, those rubber boots were particularly important.

8:15 They were manufactured by the B.F.

8:17 Goodrich Company.

8:18 When they got a hold of the device, they were convinced that, yes,

8:22 this will give us a leg up on our competitor.

8:25 We will introduce this automatic fastener, but we need a name for it.

8:30 [Gregor] Then the company's president had an idea.

8:32 Well, you know, it worked really well.

8:34 They're pretty nice.

8:35 You can just sort of...

8:36 It just goes sort of zip when you're closing it and when you're opening it.

8:40 So, B.F.

8:40 Goodrich came out in the early 1920s with their zipper boots.

8:46 The boots were such a hit that the name zipper

8:48 transcended the shoe and became the name for the fastener itself.

8:51 Soon, consumers wanted the zipper on everything.

8:57 By the 1930s, the Universal Fastener Company became very, very successful.

9:02 They got a new name, too: Talon, since their fasteners had a secure grip,

9:07 it was kind of like the talons of an eagle.

9:09 Talon's new zippers were way sturdier than Judson's hook and eye design,

9:13 because their parts were way simpler,

9:15 and they were also made out of rust resistant nickel alloy instead of steel,

9:19 which meant you could leave them on in the wash.

9:22 By the way, if you are putting

9:23 something with a zipper inside the washing machine, you should always zip it up.

9:27 That will prevent the zipper from snagging on your other clothes,

9:29 and it'll also protect the zipper itself.

9:32 Now, even though zippers rapidly became popular,

9:35 there was pushback among the older and more conservative consumers,

9:39 especially about putting them on the fly.

9:41 And urban legends began to spread.

9:44 One of the most famous ones is the myth

9:46 of the fellow who has come to his fiance's parents for dinner,

9:50 he's seated down at the table, he looked down and realized,

9:54 "Oh my God, I haven't zipped up my fly," so he zips it up.

9:58 But then when he gets up a few minutes later to leave the table,

10:02 he has caught the tablecloth in the fly of his trousers,

10:05 and so ends up sending the entire table

10:08 tumbling after him as he gets up and leaves.

10:14 I'm still a bit confused by...

10:16 zippers are more expensive, more temperamental than buttons and laces,

10:19 and anyways, they become huge regardless of that.

10:23 Well, now you see the heart of the mystery.

10:25 The novelty of a zipper itself was something that took hold of people.

10:30 People wanted to be modern,

10:32 and it came to be closely identified with being modern.

10:37 I found it very interesting that looking at World War II,

10:41 the zipper manufacturer in Germany was one of the protected industries,

10:47 despite the fact that it used fairly precious metal,

10:50 metals that were very important for munition and the like.

10:53 But the zippers were protected because

10:55 they were closely identified with modern prosperity,

10:59 with the idea that if we can have zippers then everything must be okay.

11:05 But a more obvious reason for the zipper's

11:07 popularity is that it's just so easy to use.

11:10 How much quicker is a zipper than a series of buttons?

11:13 I have a jacket that has both, so let's time it.

11:14 Three, two, one.

11:22 There we go.

11:27 I mean, it's a pretty great example of how

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12:41 And now back to zippers.

12:44 Fast forward to today,

12:45 Sundback's design is still the one we most associate with zippers.

12:48 Besides the classic metal variant, which was sturdy and reliable,

12:52 zippers also started being produced from plastic,

12:54 which was cheaper and more flexible.

12:57 But you'd probably be surprised to know that these two

12:59 zipper types aren't the most common zipper in the world.

13:02 In fact, the world's most popular zipper doesn't have teeth at all,

13:06 and it's this thing.

13:08 (dramatic music) Okay, at first it just looks like other zippers,

13:11 but if I pull out the threads,

13:13 you can see that everything here is just a single weird piece of plastic.

13:18 Imagine you have a coil of plastic that you somewhat flatten.

13:21 You can mold the plastic such that one side

13:23 of every loop bulges out more on the top and bottom.

13:27 If you do this a second time with a second piece of plastic,

13:30 you'll notice that you now have ridges that fit perfectly together,

13:33 much like zipper teeth.

13:35 Stitch these two coils onto fabric, then add a slider,

13:39 and bam, you have a functional zipper.

13:41 This is known as a coil zipper.

13:43 It showed up around the 1940s as a cheap alternative to the original design,

13:47 and now you can find it everywhere,

13:49 especially on things like suitcases and backpacks where

13:52 the zipper needs flexibility to maneuver around corners.

13:56 Coil zippers also have another benefit.

13:58 Since all of their teeth are one interconnected piece of plastic,

14:02 there's no way for a single tooth to fall off,

14:04 so that itself cannot cause that cascading failure.

14:09 But there was still a problem zippers had to solve,

14:11 and that was that they were kind of too good,

14:13 especially zippers that have been used a lot and are

14:15 kind of worn down in the slider, they can...

14:19 just unzip on their own.

14:21 To prevent that, Gideon Sundback himself actually

14:24 designed a locking mechanism like a break.

14:27 Under the piece that connects the pull tab to the slider,

14:30 there is a small metal pin.

14:32 When the pull tab is in its typical resting position,

14:35 one end of the pin sticks through a hole in the bottom face of the slider,

14:39 lodging itself between the zipper's teeth or coils.

14:42 That way the slider is stuck in place.

14:44 But when the pull tab is pulled forward,

14:47 this releases the pin, allowing the slider to move.

14:50 Now you can see that there's like this little

14:52 tiny gap through which you can see light,

14:54 and that's because the zipper stop is now engaged.

14:57 But if I grab the pull tab and start pulling,

15:00 you can see that because of the way that it's shaped,

15:02 it's actually gonna end up pushing that part up,

15:05 even though I'm pulling to the side, and that's gonna disengage.

15:09 You can try to pull apart the fly on your pants,

15:11 but unless you actually grab the pull tab and pull it down,

15:14 it is not gonna open.

15:16 These locking mechanisms aren't on every zipper,

15:18 but they're more common than you might think.

15:20 I counted up 65 zippers in this room in total,

15:23 33 of those 65 had stopping mechanisms, which is over 50%.

15:28 Which is also something I never noticed on a zipper.

15:31 But as I was hunting for zippers in my room.

15:33 I noticed something else,

15:34 on pull tab after pull tab there's no mention of Talon,

15:38 but I kept finding the same three letters instead: YKK, YKK, YKK.

15:43 YKK.

15:44 Even on clothes and objects from completely different brands.

15:48 If you look at your zipper now, you'll probably see the same thing.

15:51 So at first, I thought this might refer

15:53 to a particular style of zipper or something,

15:55 but then I Googled it, and it turns out that YKK is a company,

15:58 the biggest zipper company in the world.

16:00 If Talon has the original patent rights and they own the original zipper,

16:05 how don't I have a single Talon zipper in my room,

16:07 and how did YKK end up dominating the zipper world?

16:11 Well, Talon pretty much ruled the zipper market until the 1930s, but in 1934,

16:17 Sundback's original patent expired,

16:19 so the playing field was wide open to competitors.

16:23 That same year, Japanese businessman, Tadao Yoshida,

16:25 founded a new fastener company, the Yoshida Manufacturing Corporation, or YKK.

16:33 It began as a single workshop in Tokyo where each zipper was made by hand.

16:37 Then in 1945, that workshop was completely destroyed by allied bombs,

16:42 but Yoshida was undaunted.

16:44 He rebuilt the plant, and after the war,

16:46 he started buying zipper making machines from the US.

16:49 They improved the machine, particularly they improved the speed.

16:53 [Gregor] They then also decided to switch to manufacturing

16:56 everything in-house from the zippers themselves to the machines,

16:59 to even the boxes that the zippers were shipped in.

17:02 And YKK emphasizes quality above everything else.

17:07 So they make a real point of saying that if you have a YKK zipper,

17:11 you can depend on it utterly.

17:13 And that turned out to be an enormously successful sale tactic.

17:18 [Gregor] Around 1980, YKK surpassed Talon as the world's biggest zipper maker,

17:23 and by the early 2000s, Talon's US market share had fallen to a mere 7%,

17:28 while YKK's surged to around 45%.

17:31 YKK surpassed the 10 billion annual zipper unit sales last year.

17:37 I mean, that's a very impressive number.

17:38 Like 10 billion is crazy.

17:40 It's equivalent to more than 3 million kilometers in length.

17:45 It could be like around like 80 trips around the world.

17:50 [Gregor] And not all of these are regular everyday zippers either.

17:54 So this is an airtight, watertight zipper,

17:56 and this relies on rigid metal to metal sealing,

18:00 where nickel teeth are forced tightly together against

18:03 a rubber tape providing an extreme pressure resistance.

18:06 I mean, that looks like a mean zipper.

18:07 What's an extreme use case for a zipper like this?

18:10 Deep sea diving, submarine escape suits.

18:13 Submarine escape suits sound really cool.

18:16 In case of an emergency evacuation of a submarine,

18:18 you need a suit that can balloon up

18:20 with air to counteract the pressure of the deep ocean,

18:23 and that can provide buoyancy helping you shoot up to the surface.

18:26 But you also need to be able to put it on super quickly.

18:30 And the best option seems to be this suit

18:32 with a giant watertight and airtight zipper on the front.

18:36 Airtight zippers like these even made it onto spacesuits.

18:40 And that's the zipper.

18:41 It's this surprisingly genius invention that no one really asked for.

18:48 I hate when this happens.

18:51 I think a zipper slider may get stuck if fabric becomes caught in the chain.

18:56 So if dirt or debris enters in the zipper,

19:00 the best fix is to carefully remove any trapped fabric or debris,

19:05 or move the slider gently.

19:08 Okay, so carefully removing stuff from the zipper.

19:10 Yeah, yeah.

19:11 Because my first reaction is just like, try and jam over the slider.

19:15 So you're saying I shouldn't do that?

19:16 Yeah, no.

19:18 Move it carefully.

19:20 Carefully!

19:22 And if there isn't any visible debris causing the zipper to get stuck,

19:25 you can try lubricating the area with graphite

19:27 from a pencil in order to get the slider moving again,

19:30 because it's a great dry lubricant.

19:32 But probably the most annoying zipper problem is when

19:34 a zipper unzips on both sides of the slider.

19:37 This usually happens when the slider becomes worn or bent,

19:40 and can no longer apply enough pressure

19:42 to properly interlock the zipper elements as a result.

19:46 So the zipper chain separates behind the slider.

19:50 A worn down slider is something you might be able to fix at home.

19:52 Just take some pliers and crimp the slider together from the sides.

19:56 That will make the inner cavity more narrow, just like when it was new,

19:59 which should make it bring the teeth together again.

20:01 Just don't crimp it too tightly.

20:04 I just can't get over the fact

20:05 that the first patent Gideon Sundback submitted was around 1914,

20:09 and in those 112 years so many other

20:13 devices that we've invented have been completely transformed,

20:17 got better, got faster, cheaper,

20:19 but it seems like the zipper is mostly just the same.

20:23 So it's just that Sundback's design was that good?

20:26 It's that good.

20:27 (Robert laughing) I don't have any better explanation.

20:30 It really is.

20:31 It's that good.