(zipper whirring)

- How does a zipper actually work?

Like try to push down on a zipper

from above and it probably won't budge,

but if you just use the pull tab,

suddenly it's buttery smooth.

So how does it do this?

We've made more zippers

than there are stars in the Milky Way.

You probably used one 10 times today without even noticing,

except the only time you do is when one breaks.

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

but what is actually going on inside this thing?

I mean, obviously the teeth come together inside the slider,

but it turns out there is a surprising amount

of engineering to this thing.

All of this is too small to see on a real zipper,

which is why we made this one.

This is a video about the surprising genius of zippers.

What is that?

- This is a device that basically started it all.

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

and try to put them together in some fashion

to make them quote, "automatic", unquote.

- [Gregor] The hooks seemed very sharp,

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

- No, no.

Oh, definitely not there.

(Robert laughing)

- By the 1800s,

clothes were typically fastened using laces, buttons,

brooches, and hooks and eyes.

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

If you had a series of these fasteners

on a piece of clothing,

well, you have to close them one by one.

Most people were satisfied with the state of affairs,

but one man, American engineer, Whitcomb Judson,

thought the world deserved something better.

- The idea, primarily,

it appears to be that he would put them in shoes

and people who had to lace up would be able to do it

in one quick motion.

So that was the device that he had in mind,

and it didn't work.

- Judson was a pretty bad inventor.

Most of his patents had never gotten much traction,

but he was a great salesman.

In 1893 at the Chicago World's Fair,

he presented this fastening device as the next big thing,

claiming that in no time at all

this would replace buttons and laces, and not just on shoes,

but on all sorts of garments.

A few wealthy investors actually believed it.

So with their backing,

the Universal Fastener Company was born.

A decade later,

the company managed to carve out a small niche,

primarily selling its fasteners for women's skirts.

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

Judson's fastener design was a mess.

It jammed constantly.

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

it actually had to be removed from the garment

before you could wash it.

So literally unsewn from your skirt.

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

the whole fastener became unstable,

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

Naturally, the Universal Fastener Company

had very few repeat customers, and they fell into debt.

But in 1906, a new engineer joined the team,

25-year-old Gideon Sundback,

who had just moved to the US from Sweden.

Why does someone like Gideon Sundback

with a good degree in electrical engineering

decide to join this failing company?

- Well, it's a great story.

- [Gregor] See, one of the managers at the company had-

- An absolutely drop-dead gorgeous daughter.

(Gregor chuckles)

And that daughter came into the eye of Gideon Sundback,

and he was completely smitten.

So he ends up working for the fastener manufacturer

so that he can cozy up to that daughter and they marry.

- [Gregor] For the next few years,

Sundback made minor improvements

to Judson's hook and eye design,

but none were ever enough to make the product

truly functional.

Then soon after giving birth to a daughter, his wife Elvira,

fell ill and died.

- [Robert] And Sundback was absolutely devastated.

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

at that point out of fighting the grief

from the loss of his wife.

- This dark period in his life led to a major breakthrough.

Sundback realized that this

(paper crinkling)

was never gonna work.

So after years of tinkering,

he submitted a patent of his own.

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

it is nearly identical to a zipper from today.

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

and the teeth are shaped so that they're wider at the end

than the opening on the other side.

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

Now, this is especially true on a real size zipper

where it's practically impossible.

But if I add this slider to the bottom

and try pulling on the pull tab here,

suddenly it's effortless.

So how does it do it?

Well, I can remove the cover from the slider

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

That's it.

See, as you zip up,

the Y-shaped cavity tilts the teeth at just the right angle

so that the tooth has enough space

to slot into its groove

without bumping into the tooth above.

And as you zip down,

this wedge shaped piece separates the teeth,

allowing you to unzip.

This results in one awkward design quirk.

At the top, no zipper is ever fully zipped up

because the wedge is always there.

It has to remain between the teeth.

Now, Sundback's original design

was a little different to this big guy.

It sported rectangular teeth

with a bump on the top called the nib,

and an equivalently shaped indent

on the bottom called the scoop.

That way, when the teeth would align,

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

forming a strong connection.

But there was a problem,

even though Sundback had a new design and a patent,

manufacturing a zipper like this in the 1910s

was very impractical.

Each of the tiny teeth needed to be precisely shaped

for the fastener to work, but at the time,

there were simply no tools around

that could do this reliably.

- So he had to come up

with some extraordinarily clever machineries

that allowed them to automate the production

of the zipper from the very beginning.

- Sundback's machine worked like this.

It took Y-shaped wire

made from a nickel alloy as an input.

First, it sliced pieces off the wire

to serve as individual teeth,

and then it stamped the scoop and nib into each tooth.

Finally, the machine would clamp the two arms

of the Y-shape together onto a piece of fabric

called the tape.

This tape held all the teeth in place,

and it was the part of the zipper

that would later get stitched

onto clothes and other products.

Sundback's machines worked wonders.

Even in their earliest forms,

they could already make 150 meters of zippers per day,

and these zippers were incredibly strong.

That's because for a tooth to become unpaired,

it needs to get some distance between itself,

and its neighbors,

enough for the nibs on either side to pop out.

But since the machines spaced the teeth so precisely,

there was simply no room for that to happen.

Now, you might think you could just stretch the zipper

vertically to separate the teeth,

but the zipper tape itself is made

from strong inelastic fabric.

So even if the garment itself is stretchy,

the teeth are connected to the tape

which is designed not to stretch, so they won't come loose.

But there is a way for this mechanism to fail.

If even a single tooth falls off,

well, then its neighbors have enough space to come loose,

and then their neighbors come loose,

and this causes a cascading effect,

and the whole zipper pops open.

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

which can only fail one at a time.

But even with this flaw,

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

So the Universal Fastener Company

decided to launch the product under their new name,

'The Hookless Hooker'.

They abandoned that name pretty quickly

and decided to call it 'The Hookless Fastener' instead.

This new fastener was a successful product,

but not a mainstream one.

Its first applications were pretty niche.

You'd find it on money belts,

essentially the fanny packs of the 1910s,

as well as tobacco pouches and rubber boots.

Now, those rubber boots were particularly important.

They were manufactured by the B.F. Goodrich Company.

- When they got a hold of the device,

they were convinced that,

yes, this will give us a leg up on our competitor.

We will introduce this automatic fastener,

but we need a name for it.

- [Gregor] Then the company's president had an idea.

- Well, you know, it worked really well.

They're pretty nice.

You can just sort of...

It just goes sort of zip when you're closing it

and when you're opening it.

So, B.F. Goodrich came out in the early 1920s

with their zipper boots.

- The boots were such a hit

that the name zipper transcended the shoe

and became the name for the fastener itself.

Soon, consumers wanted the zipper on everything.

By the 1930s, the Universal Fastener Company

became very, very successful.

They got a new name, too: Talon,

since their fasteners had a secure grip,

it was kind of like the talons of an eagle.

Talon's new zippers were way sturdier than Judson's hook

and eye design, because their parts were way simpler,

and they were also made out of rust resistant nickel alloy

instead of steel,

which meant you could leave them on in the wash.

By the way, if you are putting something with a zipper

inside the washing machine, you should always zip it up.

That will prevent the zipper from snagging

on your other clothes,

and it'll also protect the zipper itself.

Now, even though zippers rapidly became popular,

there was pushback among the older

and more conservative consumers,

especially about putting them on the fly.

And urban legends began to spread.

- One of the most famous ones is the myth of the fellow

who has come to his fiance's parents for dinner,

he's seated down at the table,

he looked down and realized,

"Oh my God, I haven't zipped up my fly,"

so he zips it up.

But then when he gets up a few minutes later

to leave the table,

he has caught the tablecloth in the fly of his trousers,

and so ends up sending the entire table tumbling

after him as he gets up and leaves.

- I'm still a bit confused by...

zippers are more expensive,

more temperamental than buttons and laces,

and anyways, they become huge regardless of that.

- Well, now you see the heart of the mystery.

The novelty of a zipper itself was something

that took hold of people.

People wanted to be modern,

and it came to be closely identified with being modern.

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

the zipper manufacturer in Germany

was one of the protected industries,

despite the fact that it used fairly precious metal,

metals that were very important for munition and the like.

But the zippers were protected

because they were closely identified with modern prosperity,

with the idea that if we can have zippers

then everything must be okay.

- But a more obvious reason for the zipper's popularity

is that it's just so easy to use.

How much quicker is a zipper than a series of buttons?

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

Three, two, one.

There we go.

I mean, it's a pretty great example

of how a more automatic approach

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And now back to zippers.

Fast forward to today,

Sundback's design is still the one

we most associate with zippers.

Besides the classic metal variant,

which was sturdy and reliable,

zippers also started being produced from plastic,

which was cheaper and more flexible.

But you'd probably be surprised to know

that these two zipper types

aren't the most common zipper in the world.

In fact, the world's most popular zipper

doesn't have teeth at all, and it's this thing.

(dramatic music)

Okay, at first it just looks like other zippers,

but if I pull out the threads,

you can see that everything here

is just a single weird piece of plastic.

Imagine you have a coil of plastic

that you somewhat flatten.

You can mold the plastic such that one side

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

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

you'll notice that you now have ridges

that fit perfectly together,

much like zipper teeth.

Stitch these two coils onto fabric, then add a slider,

and bam, you have a functional zipper.

This is known as a coil zipper.

It showed up around the 1940s as a cheap alternative

to the original design,

and now you can find it everywhere,

especially on things like suitcases and backpacks

where the zipper needs flexibility

to maneuver around corners.

Coil zippers also have another benefit.

Since all of their teeth are one interconnected piece

of plastic, there's no way for a single tooth to fall off,

so that itself cannot cause that cascading failure.

But there was still a problem zippers had to solve,

and that was that they were kind of too good,

especially zippers that have been used a lot

and are kind of worn down in the slider,

they can...

just unzip on their own.

To prevent that,

Gideon Sundback himself actually designed

a locking mechanism like a break.

Under the piece that connects the pull tab to the slider,

there is a small metal pin.

When the pull tab is in its typical resting position,

one end of the pin sticks through a hole

in the bottom face of the slider,

lodging itself between the zipper's teeth or coils.

That way the slider is stuck in place.

But when the pull tab is pulled forward,

this releases the pin, allowing the slider to move.

Now you can see that there's like this little tiny gap

through which you can see light,

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

But if I grab the pull tab and start pulling,

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

it's actually gonna end up pushing that part up,

even though I'm pulling to the side,

and that's gonna disengage.

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

but unless you actually grab the pull tab

and pull it down, it is not gonna open.

These locking mechanisms aren't on every zipper,

but they're more common than you might think.

I counted up 65 zippers in this room in total,

33 of those 65 had stopping mechanisms,

which is over 50%.

Which is also something I never noticed on a zipper.

But as I was hunting for zippers in my room.

I noticed something else,

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

but I kept finding the same three letters instead:

YKK, YKK, YKK.

YKK.

Even on clothes and objects

from completely different brands.

If you look at your zipper now,

you'll probably see the same thing.

So at first, I thought this might refer

to a particular style of zipper or something,

but then I Googled it,

and it turns out that YKK is a company,

the biggest zipper company in the world.

If Talon has the original patent rights

and they own the original zipper,

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

and how did YKK end up dominating the zipper world?

Well, Talon pretty much ruled the zipper market

until the 1930s,

but in 1934, Sundback's original patent expired,

so the playing field was wide open to competitors.

That same year, Japanese businessman, Tadao Yoshida,

founded a new fastener company,

the Yoshida Manufacturing Corporation, or YKK.

It began as a single workshop in Tokyo

where each zipper was made by hand.

Then in 1945, that workshop was completely destroyed

by allied bombs, but Yoshida was undaunted.

He rebuilt the plant, and after the war,

he started buying zipper making machines from the US.

- They improved the machine,

particularly they improved the speed.

- [Gregor] They then also decided to switch

to manufacturing everything in-house

from the zippers themselves to the machines,

to even the boxes that the zippers were shipped in.

- And YKK emphasizes quality above everything else.

So they make a real point of saying

that if you have a YKK zipper, you can depend on it utterly.

And that turned out

to be an enormously successful sale tactic.

- [Gregor] Around 1980,

YKK surpassed Talon as the world's biggest zipper maker,

and by the early 2000s,

Talon's US market share had fallen to a mere 7%,

while YKK's surged to around 45%.

- YKK surpassed the 10 billion annual zipper

unit sales last year.

- I mean, that's a very impressive number.

Like 10 billion is crazy.

- It's equivalent

to more than 3 million kilometers in length.

It could be like around like 80 trips around the world.

- [Gregor] And not all of these are regular

everyday zippers either.

- So this is an airtight, watertight zipper,

and this relies on rigid metal to metal sealing,

where nickel teeth are forced tightly together

against a rubber tape

providing an extreme pressure resistance.

- I mean, that looks like a mean zipper.

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

- Deep sea diving, submarine escape suits.

- Submarine escape suits sound really cool.

In case of an emergency evacuation of a submarine,

you need a suit that can balloon up with air

to counteract the pressure of the deep ocean,

and that can provide buoyancy helping you shoot up

to the surface.

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

And the best option seems to be this suit

with a giant watertight and airtight zipper on the front.

Airtight zippers like these

even made it onto spacesuits.

And that's the zipper.

It's this surprisingly genius invention

that no one really asked for.

I hate when this happens.

- I think a zipper slider may get stuck

if fabric becomes caught in the chain.

So if dirt or debris enters in the zipper,

the best fix is to carefully remove any trapped fabric

or debris, or move the slider gently.

- Okay, so carefully removing stuff from the zipper.

- Yeah, yeah.

- Because my first reaction is just like,

try and jam over the slider.

So you're saying I shouldn't do that?

- Yeah, no.

Move it carefully.

- Carefully!

And if there isn't any visible debris causing the zipper

to get stuck,

you can try lubricating the area with graphite from a pencil

in order to get the slider moving again,

because it's a great dry lubricant.

But probably the most annoying zipper problem

is when a zipper unzips on both sides of the slider.

- This usually happens when the slider

becomes worn or bent,

and can no longer apply enough pressure

to properly interlock the zipper elements as a result.

So the zipper chain separates behind the slider.

- A worn down slider is something

you might be able to fix at home.

Just take some pliers

and crimp the slider together from the sides.

That will make the inner cavity more narrow,

just like when it was new,

which should make it bring the teeth together again.

Just don't crimp it too tightly.

I just can't get over the fact

that the first patent Gideon Sundback submitted

was around 1914,

and in those 112 years so many other devices

that we've invented have been completely transformed,

got better, got faster, cheaper,

but it seems like the zipper is mostly just the same.

So it's just that Sundback's design was that good?

- It's that good.

(Robert laughing)

I don't have any better explanation.

It really is. It's that good.