All language subtitles for S04E06 - Brushes and Push Brooms; Blackboards; Smoked Salmon; Zippers (576p AMZN WEB-DL x265 Garshasp)_track4_[eng]

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

Brushes and push brooms...

...Blackboards...

...Smoked salmon...

...And zippers.

Nothing scrubs or sweeps quite
Like a good, sturdy brush.

Cleaning brushes
In north america

Date back to about the 1830s.

Their bristles were usually made
Of wire twisted into wood.

Today we have many different
Bristle materials,

Both natural and synthetic.

The first factory manufactures
The brush block --

The hardwood base
That holds the bristles.

It's usually made of maple,
But sometimes oak or beech.

After cutting the planks
To the required width,

They use a special wax crayon
To mark lines

On both sides of any cracks
Or knots in the wood.

A laser then reads the marks,

Guiding a saw
To cut out the faults.

At the same time,

The saw chops the planks
Into block-size lengths.

The next step
Is called "Molding."

A series of saws
Trims the blocks

To the required thickness.

Now they contour the pieces,

Using a machine appropriately
Called a shaper.

The machine revolves,

Running the block's outside edge
Against a cutting head.

This profiles half the block.

Workers then turn it around

And line it up
For a second pass

To profile the other half.

There's a different shaper
Machine for each model.

This type is known
As a dauber --

A brush for waxing shoes.

For the cuts to be accurate
And smooth,

It's essential that
The machine's cutting heads

Remain sharp
Despite repeated use.

That's why they're made
Of carbide,

A material stronger than steel.

Workers run certain models
Against an extra cutting head

To carve a groove
In the block's edges.

The groove gives your hand
A better grip on the brush.

These 2 1/2x24" blocks
Will become push brooms --

Those wide, rectangular brooms

Janitors use to sweep floors.

The blocks go
To an automated machine

That drills a hole
Through the middle

And carves two grooves
In the underside.

These are for the steel adapter

That will hold the broom's
Wooden handle.

Rounded push brooms
Sweep more easily in corners.

To produce those,

Workers take the rectangular
Push broom blocks

And round the corners
Against a cutting head.

At another factory,
The blocks go onto a machine

That pierces holes
For the bristles,

Using a computer-guided drill.

This particular model
Of push broom needs 240 holes.

It takes barely a minute
To drill them all.

Next, the blocks go to the
Bristle-installation machine.

Bristles can be made
Of horsehair, vinyl,

Plants or tree leaves,

Or synthetics
Such as polypropylene.

The bristle-installation machine
Is fully automated,

As we see here in slow motion.

It takes about 40 strands
At a time, folds them in half,

Then inserts and staples them
Into a hole.

Here's what that
Bristling action looks like

At actual speed.

The machine fills four holes
Per second.

The factory uses
This same process

Regardless of the style of brush
Block or type of bristle.

Computer software
Guides the machinery

To follow the correct pattern,

Making possible a sweeping array
Of brushes and brooms.

Narrator: chalk one up
For the blackboard.

This trusted teaching tool
Goes back centuries,

Yet still remains the focal
Point of the classroom.

Today's blackboard --

Or chalkboard,
As it's also called --

Hasn't changed that much
In appearance,

But the materials
Used to make it have changed.

Our lesson begins
At the blackboard factory,

With thin sheets
Of galvanized steel.

These will eventually form

The front and back surfaces
Of the blackboard.

They arrive at the factory

Already precut
To standard sizes --

6, 8, 10, or 12 feet.

First stop is a machine that
Blasts the sheets with acid.

This removes any dirt

That would prevent paint
From adhering to the surface.

As the sheets exit the cleaner,
Powerful fans dry them off.

The paint is a type
Of acrylic enamel

Designed especially
For blackboards.

The factory adds
A powdered mineral formulation

To make it dry
To a rougher texture.

This helps chalk adhere better.

Traditional slate blackboards
Were naturally black.

Today's steel-surface boards
Come in several colors.

The most popular, though,
Are black and green.

Some companies use colored
Porcelain instead of paint.

Here, spray guns apply
Three coats of paint,

One after another,

With no drying time in between.

For the paint to harden
Properly, it has to be heat-set,

So the sheets go into an oven

At 420 degrees fahrenheit
For 10 minutes.

A strong fan cools them off
As they exit the oven.

Next, a worker
Sprays contact cement

On the backs
Of two painted sheets.

One sheet will form
The front of the board,

The other, the back.

Sandwiched in between

Will be what's known
As the blackboard's core.

It can be made of materials
Such as particleboard

Or, as we see here,
1/2-inch-thick fiberboard.

Workers feed
The three assembled layers

Through a high-pressure roller.

It forces out any trapped air
And bonds the layers tightly.

They make the blackboard's frame

Out of one long strip
Of aluminum molding.

It has a stainproof
Satin finish.

They make a series
Of 45-degree-angle cuts.

This enables them
To bend the strip

Around the board's perimeter,

Creating neat corner seams.

Workers file down and polish

Any sharp edges
Left by the cutting.

After verifying that
It's perfectly square,

They fasten the frame,

Using either rivets or screws,
Depending on the model.

Then, they attach an aluminum
Rail along the bottom

To hold the chalk and erasers.

This model happens to be

A reversible
Mobile blackboard --

The type typically rolled
Into conference rooms.

It has a few extra components --
A pivot mechanism,

Enabling the board to be flipped
To the other side...

And a latch system

For tilting the board
To different angles.

The blackboard stand is made
Of painted steel tubing.

It rolls on rubber-
And chrome-plated steel castors.

The factory takes samples
From the production line

And subjects them to rigorous
Quality-control testing.

These tests ensure

That the painted surface
Is glare-free

And can withstand everything
From chemical solvents

And extreme humidity

To heavy impact
And hard scratches.

The company has even designed
This special machine

To conduct a killer
Durability test.

It applies 100,000
Chalk and brush strokes,

Using the typical amount
Of pressure a person would use.

For the production batch
To make it to market,

Surface wear on the sample

Has to amount to less than
1/100 of a millimeter.

And that's not all.

The paint finish
Must still be matte.

A writing test
Has to produce chalk lines

That are clear and dark enough,

And the writing has to erase
Cleanly and easily.

Narrator:
For thousands of years,

Smoked fish was a survival food.

People would cure their catches

By salting them
And hanging them to dry

Or by smoking them
Over an open fire.

This enabled people
In cold climates

To stockpile nutrient-rich fish
For those long winter months.

Today we smoke fish primarily
To enhance its flavor.

This is wild sockeye salmon

That was gutted and frozen
On board the fishing trawler

To preserve maximum freshness.

The smokehouse defrosts the fish

For over 15 hours
In running water

That's just 2 degrees
Above freezing.

This slow, cold water thaw

Helps prevent bacteria
From forming.

Next step, filleting.

First, they slice off
What's known as the collar --

The fish version of a neck.

Then, they cut each fish in half
Lengthwise,

Separating two fillets

From what's called
The control bone --

The fish equivalent
Of a spinal column.

The tail is attached to it.

They feed the control bones
Into a machine

That strips off any
Remaining scraps of flesh.

The machine grinds these bits
Into minced salmon,

Which is used to make
Salmon pie.

They trim the fillets
Using a razor-sharp knife,

Slicing off the fins,
Any excess fat,

And any control-bone fragments
Left behind.

After this, the fish will be
Ready for curing --

A preservation process
That also enhances taste.

Workers coat the fillets in
A mixture of salt and 26 spices,

Then let them sit for roughly
An hour and a half.

This short cure time

Will limit the salmon's
Salt content to less than 1%.

To stop the curing process,

They rinse off the coating
With cold water,

Then glaze the fillets
With maple syrup

To neutralize
Any remaining salt residue.

Some companies
Use a less costly mix

Of boiled water and brown sugar.

The fillets go into
A huge smoke oven.

Workers load its combustion
Chamber with sawdust --

Maple-tree sawdust for
The first 8 hours of smoking,

Cherry-tree sawdust
For the next 8 hours,

And apple-tree sawdust
For the last 8 hours.

This particular sequence

Is a major factor
In flavoring the fish.

They douse the fire with water
To generate smoke.

This process
Is called "Cold smoking,"

Because the oven temperature
Is 50 degrees fahrenheit --

Significantly lower than
The industry norm of 77 degrees.

Smoking at this
Lower temperature

Takes at least 24 hours --
3 times longer than the norm --

But the company says
It produces a moister product.

When the fillets
Come out of the smoke oven,

They're thoroughly cooked

But still have the consistency
Of raw fish.

Workers remove the fin bones --
40 fin bones per fillet --

Located between
The head and fin.

The fillets then go through
A skinning machine,

Which neatly slices off the skin
Without removing any flesh.

Then, it's into a freezer
At 27 degrees fahrenheit.

This firms up the fillets,
Making them easier to slice.

The manual slicing machines
Cut them into pieces

About 1/10 of an inch thick.

Workers weigh out the amount
They're packaging --

In this case, 2 1/2 ounces.

They place each portion
On a tray

Made of aluminum-coated
Cardboard.

Aluminum blocks the fat
From seeping through.

To kill off
Any remaining bacterial,

They vacuum-pack the wrappers,

Then deep-freeze them
For about an hour

At negative-31
Degrees fahrenheit.

They store and ship
At a milder zero degrees --

The temperature
Of your home freezer --

Where this preservative-free
Smoked salmon

Stays fresh for a full year.

Narrator: zippers
Can be found on clothing,

On bags, even on footwear.

The zipper started out as
A closure mechanism for boots

And tobacco pouches.

The fashion industry
Didn't put them on clothing

Until the 1930s --

Some 80 years
After the invention

Of this fabulous fastener.

An american, elias howe,
Was the first to patent

A zipperlike clothing fastener
In 1851,

But he never ended up
Marketing it.

It wasn't until 1893
That another american,

Whitcomb judson,
Designed a similar device,

Called a clasp locker.

He eventually hired a canadian
Engineer, gideon sundback,

To simplify the original
Complex design,

Which had never really
Taken off.

In 1917, judson and sundback
Patented the modern zipper.

Zipper teeth are made of metal,
Plastic, or nylon.

The fabric part of the zipper
Is called the tape.

It's usually polyester,

But sometimes cotton
Or fireproof fabric.

To make metal zippers,

The factory feeds a long,
Continuous roll of tape

Into what's called
The teeth machine,

Along with a long roll of metal
Ribbon known as "Flat wire."

As we see here in slow motion,

The machine cuts off
A tiny piece of flat wire,

Forces it through a die
That forms into a tooth shape,

Then clamps it onto the edge
Of one side of the tape.

The machine does all this at
A rate of 45 teeth per second.

These zipper teeth are aluminum.

Sturdier zippers
Are made of stronger metals

Like brass and nickel.

Depending on the model,

Teeth can range in width

From about 1/10 of an inch
To 4/10 of an inch.

The wider the teeth,
The thicker they have to be.

Workers now feed two tapes
With metal teeth

Into what's called
The joining machine.

The teeth interlock,

Meshing the two halves of what's
Now a continuous zipper.

From there, it's into
A cleaning machine,

Which washes the zipper,

Removing any shards of metal
Left behind

By the tooth-cutting process.

After drying the zipper,

The machine applies
A coat of hot wax.

This lubricates the teeth

So the slider will glide
Over them smoothly.

Next stop
Is the gapping machine.

It removes a 2-inch-long section
Of teeth at regular intervals.

They'll later cut the tape
At these gaps,

Dividing the continuous zipper
Into several shorter zippers.

There are two main types
Of zippers.

Closed-end zippers are the kind

Whose two halves don't separate
At the bottom when opened --

Purse zippers, for example.

These need a part
Called a bottom stop --

A thick piece of flat wire

Positioned at the base
Of the zipper.

When you unzip,
It stops the slider

And prevents the two halves
From separating.

Open-end zippers are the kind

Whose two halves doseparate
At the bottom when opened --

Jacket zippers, for instance.

At the bottom of these zippers,

A machine applies
A clear reinforcement strip.

This stiffens the tape

So that the next machine
Can apply the pin and box.

The pin is that vertical piece
Of metal

On one half of the zipper

That you have to align
In the box on the other half

Before you can pull the slider
To zip up.

The next machine
Installs the slider.

Watch in slow motion
As it opens each gap

And hooks a slider
Onto the track of teeth.

The next machine inserts
What's called the top stop --

A thick piece of flat wire

That stops the slider
At the top of the track

When you zip up all the way.

The machine then slices the tape
At each gap,

Separating the finished zippers.

Plastic zippers are made quite
Differently than metal ones.

The tape is the same,

But the teeth are made
From plastic pellets.

A machine melts them,

Then injects the liquid plastic
Into a mold

That's the shape of a strip
Of zipper teeth.

The mold cools almost instantly,
Hardening the plastic.

The machine then stamps
The teeth onto the tape,

Automatically gapping
The desired zipper length

At the same time.

The excess plastic in the middle
Is remelted.

There's no joining machine

To mesh the two halves
Of plastic zippers.

Workers do this manually

So that they can inspect
The plastic teeth

To make sure
They're well formed.

Then, automated machines install
The remaining components.

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