All language subtitles for S02E07 - Carpets; Drinking Water; Laser Eye Surgery; Acoustic Guitars (576p AMZN WEB-DL x265 Garshasp)_track4_[eng]

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Narrator:
Today on "How it's made,"

Carpets,

Drinking water,

Laser-eye surgery,

And acoustic guitars.

People use the words "Rug"
And "Carpet" interchangeably,

But they're not the same thing.

A rug covers
Just part of the floor.

A carpet goes wall to wall.

Today most carpets on the market
Are made of synthetic materials.

The first step
Is to make the carpet yarn.

They start by feeding bales
Of nylon or polyester fiber

Into the opening
And blending machine.

The carding machine then
Untangles the individual fibers,

Lining them up in neat rows,

Then gathering them
Into wider bands.

The bands go into cans.

From the cans,

They go into a machine
Called a drawing frame...

Which draws out five threads

To make one rough, loose thread.

That thread goes onto spools.

Then they twist threads
From two spools

To make a stronger
And thicker thread.

Next they twist
Two of those threads together

To form a two-ply yarn.

To ensure
The two plies don't untwist,

The yarn goes through
A heat-setting machine

At almost 270 degrees
Fahrenheit.

The continuous heat
Permanently sets it,

Much the way a curling iron
Sets hair.

After 45 seconds
Of heat-setting,

The yarn is rewound on spools.

Those spools then go
To the tufting department,

Where the carpet-making begins.

A standard 144-inch-wide carpet

Is made from
1,440 spools of yarn.

Each spool
Feeds into a plastic tube,

Which feeds into
The tufting machine,

Where the 1,440 lines of yarn

Feed 1,440 tufting needles.

The needles stitch the yarn

Into a canvas backing
Made of polypropylene.

With slow motion,

You can see the yarn
Being hooked on the canvas

Then cut underneath
Into carpet pile.

Up to 12 needles
Work each inch of canvas.

The result is a pile carpet
In the standard 12-foot width.

Next they dye it.

For multicolored carpets,

They use a machine
Called a chromojet.

It works much the way
A computer ink-jet printer does,

Forcing streams of dye
In different colors

Into the carpet fibers.

The more complicated
And colorful the design,

The more often the machine
Passes over the carpet.

For solid-color dyeing, there's
A mixer in each dye reservoir

To keep the color even.

They soak the carpet
For four hours

In a hot bath of dye and water

Heated to
212 degrees fahrenheit.

Another method uses heat and
Air pressure in an autoclave.

What the bath method does
In four hours,

This method does
In just 30 minutes

And with more carpets at a time.

Once the dyeing is finished,

They apply a water-based glue
To a polypropylene backing

Then put the backing over
The original canvas backing,

Locking the carpet fibers
In place.

Then it's on to what's called
The marriage roll,

A roller press that marries
The two backings together.

After a quick run
Through an oven

To make the water
And the glue evaporate,

They cut the finished carpet
Into rolls.

A standard roll
Is 100 feet long.

Narrator: researchers have
Invented a pollution-free car

That runs on hydrogen.

The research team
Modified the standard car engine

To burn hydrogen
Instead of gasoline.

Now they have to figure out

How to prevent the hydrogen tank
From blowing up in a collision.

Drinking water that's fresh,
Clean, and crystal-clear

Is something many of us
Take for granted.

We might not give it
A second thought,

But between the source
And our tap,

A lot happens
To make that water fit to drink.

Our water
May come from mother nature,

But it's far from pristine.

It starts its journey
To the treatment plant

Through a water-intake pipe.

On the wall of that pipe,
About 6 1/2 feet down,

Is a 6-inch hole.

Covering that hole
Is a metal grill

Designed to keep out large
Debris, such as tree branches.

The water flows
To the pumping station,

Where it goes through
A preliminary screening.

A giant revolving screen removes
Fish, garbage, and grass.

Once they remove the debris,

A low-pressure pump moves the
Water into the treatment plant.

The untreated water,
Called raw water,

Is dirty and smelly.

They first add a powerful form
Of the chemical element carbon

Called activated carbon.

It absorbs contaminants
Such as solvents and pesticides.

That rids the water of bad taste
And odor.

From there,

The water then goes through
A series of mixing tanks.

The first tank holds a chemical
Called aluminum sulfate.

It acts as a coagulant,

A substance
That thickens liquid into globs.

In the raw water,

The aluminum sulfate forms tiny,
Sticky globs called flocks.

Bacteria, mud,
And other impurities

Stick to those flocks.

Then the flock-filled water

Moves on
To the second mixing tank.

The second tank holds
A chemical called polymer,

Which is essential to
The next step of the process,

Called sedimentation.

Five pipes inject the water with
Superfine particles of sand,

Called microsand.

The polymer coats the sand,
Making it sticky.

The grains of sand then stick
To the flocks in the raw water,

Weighing them down even more.

The water then flows into
A settling tank,

Where the flocks,
Because they're heavier,

Settle to the bottom.

You can see the result
In this demonstration.

The water is finally clear,
But it's far from drinkable

Because it's still full
Of bacteria, viruses,

And other organic matter.

So, on to the next step --
Filtration.

The water flows
Onto the top of the filter

Then trickles downward,

Passing through a layer
Of anthracite, a type of coal,

Then through a layer of sand.

This filters out
Any remaining particles,

Which then flow to the middle.

But the water is still teeming
With bacteria and viruses,

So it has to be disinfected.

They add 1.9 milligrams
Of chlorine

For every 4 cups of water,

Enough to kill off those germs
And bugs.

Then they add a mineral
Called silicate

To prevent calcium buildup
From blocking our water pipes.

The treatment plant

Sends water samples
To a government inspector,

Who continuously monitors
The water supply

To ensure it meets
Safety standards.

The amount of chlorine
Remaining in our drinking water

Is 20 millionths of an ounce
Per liter.

The chlorine gas the plant uses
Is highly toxic.

Should any leak out,

Emergency teams would have to
Evacuate a 6-mile radius.

So the plant stores
The drums of chlorine

In a high-security area.

It's taken about 45 minutes

To turn raw water
Into treated water.

Now these electric motors

Will pump it through underground
Pipes, right to your tap.

Narrator: short-sightedness,
Far-sightedness, and astigmatism

Are all due to light
Not focusing precisely

Onto the retina.

Surgeons can correct this
By using a laser

To reshape the curvature
Of the front surface of the eye,

Called the cornea.

The surgeon operates
On one eye at a time.

He cleans the eye, the lid, and
The lashes with antiseptic...

And administers anesthetic drops
To freeze the eye and lid.

He opens the lid wide
With a speculum

Then rinses the eye
With a saline solution.

Everything's frozen, so the
Patient doesn't feel a thing.

Next -- antibiotic drops
To prevent infection.

Before every operation,
The surgeon tests the equipment.

He fires the laser
On a metal plate

To test its energy level.

The surgeon administers
A few more anesthetic drops...

...Then inspects
The microkeratome,

The device he'll use
To lift a very thin layer

From the outer surface
Of the eye.

He also measures
The patient's cornea

Using an ultrasonic instrument.

The cornea must be
A minimum thickness

For it to be safely reshaped.

The surgeon uses the speculum
Again to prop the lid open.

Then he begins the operation.

He marks the eye
With sterile ink,

Reference marks he'll use later.

Next he positions a metal ring
Around the cornea.

The ring is attached
To a suction pump

So it clings to the eye.

Like holding a tomato steady
While you slice it,

It holds the eye steady while
The surgeon cuts the tissue.

The surgeon lubricates the eye
With sterile water

Then mops up the excess water
With a small, absorbent sponge.

Then he takes the microkeratome

And slips it into grooves
In the metal suction ring.

In a matter of seconds,
The device moves across the eye,

Cutting open a flap of tissue,

The same way a carpenter's plane
Shaves a layer of wood.

The surgeon uses
A sterile sponge ring

To keep tears
From contaminating the cornea.

He folds back the flap
Of tissue, exposing the cornea.

He mops up the excess liquid...

...Then starts up the laser.

Meanwhile, a tiny sponge
Keeps the flap moist.

The laser, an invisible light,

Fires in pulses --
50 pulses per second.

Each pulse vaporizes an area
Of corneal tissue

100 thousandths
Of an inch thick.

The laser has been
Computer-programmed beforehand

So it knows exactly
How to reshape the cornea

To give most patients
20/20 vision.

In less than a minute,
It's done.

The surgeon removes the sponge

And then using those little
Ink marks he made earlier

As reference points,

Folds the flap back
To its original position.

If the flap isn't precisely
Where it was before,

The patient
Will have distorted vision.

Using a syringe that flushes
The area with sterile water,

The surgeon carefully
Smoothes the flap

The same way
You'd smooth out a tablecloth.

Then he removes the sponge ring.

Within 45 seconds,

The negative pressure inside the
Cornea sucks the flap back on.

The flap literally seals itself.

With a sponge, the surgeon
Dabs up any excess water.

He applies antibiotic drops
As a preventive measure

Then inspects
The microkeratome again

Before moving on
To the other eye.

He takes the speculum off,
Tapes the eye closed,

Then performs the same operation
On the other eye.

When that's done, the surgeon
Uses a high-powered microscope

To make sure the flaps
Are wrinkle-free.

The patient wears protection
Shields until the next morning

Then overnight for a week.

Narrator: the best guitars come
From trees about 800 years old,

Trees with enough rings
In their trucks

To provide wood with a tight
And straight grain,

Wood flexible enough to vibrate,

Yet strong enough to withstand
The pull of the guitar strings.

The guitar traveled
From north africa to europe

With the moors, who invaded
Spain in the 8th century.

In time, the guitar became
The signature instrument

Of spanish flamenco music

And the trademark
Of the singing cowboy.

In the 1930s,

The acoustic guitar debuted
As a jazz instrument.

By the 1960s, as the electric
Guitar took over rock 'n' roll,

The acoustic guitar remained a
Staple of the folk-music scene.

They use spruce or cedar

Because those woods are
Lightweight and vibrate well.

Using a 30-ton press
That works like a cookie cutter,

They punch out
The shape of the guitar.

The size of the sound hole

Affects how the guitar
Will sound --

The larger the hole,
The more treble,

The smaller the hole,
The more bass.

Then they glue on a wood inlay
Decoration called a rosette.

Next they make
The sides of the guitar.

They first immerse wood pieces
In boiling water

For about 15 seconds...

...Then place them in a
Heated press to make the curve.

The press applies heat
From both the top and the bottom

For about a minute.

Then they connect the two sides

With blocks of wood made of
Either mahogany or poplar.

One is glued and clamped at the
Bottom, the other at the top.

Then they glue on
And clamp a wooden lining

Which will connect the sides
To the top and back.

Those little cuts give it
Flexibility around the curves.

Then with a hand router,

They carefully notch the lining
To receive four wooden braces

To support
The back of the guitar.

Strategically placed braces
Help the top of the guitar

Withstand the tension
Of the strings.

They also equalize
Sound frequencies

By controlling vibration
Differently at different spots.

After a vacuum press makes
The bracing adhere evenly,

They glue on the top and bottom.

The body of the guitar
Is now assembled.

It goes into a press, then
A drying rack for several hours.

Next they glue on
A plastic binding

To protect the guitar's edges.

Then comes a fine sanding.

Next a machine
With a special sensor

Measures the precise angle

At which the body
And neck of the guitar

Will later be attached.

The angle is critical
For sound quality.

It drills the holes and sands
The pieces accordingly.

Next they apply lacquer --

Four to eight coats,
Depending on the finish.

The fingerboard
Is made of rosewood or ebony.

The metal frets separate the
Halftones on the musical scale.

An adjustable rod
Goes inside the neck.

This lets the neck
Adapt to the different tensions

That different types of strings
Require.

They glue the fingerboard
On the neck...

...Then vacuum-press it
To make sure it adheres evenly.

Next they install
The machine heads

On which the strings
Will be wound.

The rod in the neck slips into
A groove on the body.

The neck is then bolted and
Clamped until the glue dries.

Next they glue on the bridge,

Securing it with temporary
Screws and a clamp.

Then they glue on
The headstock nut,

A hard, plastic piece
That spaces the strings evenly.

Next comes the saddle,
Then the bridge pins,

Which lock the strings
In the bridge.

Finally they string the guitar
Using an electric winder.

Because of
All the glue-drying time,

It takes three weeks
To make a guitar.

The wood will become suppler
The more the guitar is played,

So as the guitar ages,
The better it will sound.

If you have any comments
About the show,

Or if you'd like to suggest
Topics for future shows,

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