How A Master Knife Sharpener Saves Broken Knives

[upbeat music] Nice and sharp.

Today we're gonna be going over everything you need to know

about repairing your knives at home.

Tools I use for sharpening

and repairing knives are whetstones.

With the whetstones you can match the angle of your knife.

Before you use your stones, you need to prep them.

All you need to properly use them is tap water, right here.

The stones I'm soaking are the rough stones

and the medium stones.

And when you soak it in water at first

you'll see like, air bubbles start to form

and you wanna basically wait

till all the air bubbles have settled down.

That's when you know your stone is fully saturated

and ready for you to use for sharpening.

As you can see, I didn't soak the finishing stone

because those are a little bit more delicate

and if I soak it in water for too long

it can actually crack,

and I've cracked a few

'cause I've left it in water overnight.

Come in the next day [laughs] and I see two pieces.

Before we actually sharpen it,

I want to make sure that I don't miss any chips

so I like to take the piece of paper

and cut through from heel, all the way to the tip.

[paper rasps] And every time it catches

I know that's exactly where a chip in the knife is.

So I wanna make sure that I see and inspect

and make sure I'm aware of where all the chips are

so I don't miss anything when I grind it out.

The paper test shows that this has microscopic chips.

Obviously, there's some that's very noticeable

but there's a lot of little ones all along the edge.

So I wanna make sure I don't miss any of that

when I grind on the rougher stone.

A lot of times people try to sharpen the knife

and fix the knife in one shot.

But I always say it's best to think of it

as two separate processes.

So the first thing we're gonna focus on

is just grinding out the chips.

For that I'm gonna use the rougher stone I have.

This is the 220 grit rough stone.

I have here just the stone base.

This is just gonna secure the stone

and give a little bit more grip.

It also adds a little bit of height

from the table so it makes sure that my knuckle

clears the table when I'm sharpening.

This is not required to sharpen your knife

but I just like to have a little extra height.

The goal right now is to just grind metal

这所有的芯片都消失了。

So the first side I'm gonna do

is just work on my left side, facing down.

When I do this, my thumb is on the spine,

my index finger is on the heel.

Three fingers around the handle

for a nice firm grip.

I want to have full control of the knife

when I'm doing this.

This right here, is a double beveled knife,

which means that I have to sharpen

[knife scrapes] and grind both sides.

This particular knife is sharpened symmetrically

so I wanna make sure that I grind

the same amount on both sides

to keep everything even.

I'm just gonna use a very steep angle.

I like to hold a knife around four o'clock or five o'clock

in terms of position so I'm not wobbling around.

'Cause if I wobble around

the angle's constantly changing,

that really affects the outcome of the edge.

My right hand is really focusing

on the angle of the knife

and moving the knife up and down.

My left hand is really applying all the pressure.

When I flip over, I'm gonna change my grip a little bit.

My thumb is gonna be on the heel,

my index finger on the spine.

And just like before, I hold the knife

at a four o'clock or a five o'clock position.

I'm applying a good amount of pressure

with my left hand.

I'm pressing firmly, but I'm not pressing

with all my might because that could be dangerous.

If I slip, I can really hurt myself.

I actually prefer sharpening, standing,

'cause I can use my body weight

and that's gonna make it easier to grind faster,

apply a good amount of pressure.

So every now and then I'm gonna wipe the knife

and check to see my progress.

And you can see already

that the chips are starting to come out.

There's only a few more pieces left.

[knife scrapes]

So you see me constantly wiping my blade

'cause a lot of times,

if you have a high carbon steel knife,

it can actually rust as you're sharpening.

If you leave the knife on the table

with a few drops of water,

you'll see a little particles of rust.

If you cut anything acidic

you can actually see discoloration almost immediately.

So with high carbon steel,

the key is constantly wiping your blade

even as you're sharpening, even as you're using it.

This particular one is stainless

so I don't have to worry about it.

But since I'm so used to it,

I just like to constantly wipe my knife.

So as I'm sharpening on the stone,

the stone is actually wearing down.

And to make sure that I have this flat even, surface,

even as I'm sharpening,

I like to periodically stop and use a stone fixer.

If your stone looks like a half pipe,

it's gonna be very hard to repair.

So to avoid that, I always say,

try to use this as frequently as you can.

So I worked on the stone a little bit with the fixer,

I can just continue grinding my knife.

[knife scrapes]

And I think we're good to go.

Now that I've grinded all the chips out,

this knife is just a little bit smaller,

but for usage, for function,

it's not gonna make a difference and it's barely noticeable.

We can move on to the sharpening

and creating an edge on this knife.

For that, I'm gonna use the same stone,

this is the rough stone that I've been using.

So I like to take two pennies,

stack them up and place them on the stone.

And what I do is I lay the spine of the knife

onto these pennies,

and that's gonna give you a rough guideline

on what the angle should be.

By working on the two pennies on the backside

I'm creating a plane on that side.

I'm gonna do the same amount on the other side,

and those two planes intersecting

will create a perfect edge.

I'm gonna place my two fingers right on that very tip

and I'm gonna press firmly as I pull straight down.

When I go back up, I'm actually not applying pressure.

I'm gonna release pressure as I go back up,

apply pressure as I pull, coming back towards me.

And when I go back up, I move my fingers slightly over.

And I continue to work my way down the knife in sections.

[knife scrapes]

If I apply pressure towards the edge,

my knife can actually cut into the stone.

I'm gonna flip over,

and do the same thing for the other side.

However, this time the edge is facing me.

I start at the bottom of the stone,

place two fingers right on the tip,

and I apply pressure as I push away.

Come back down,

push away.

The angle that I'm using,

I'm making sure it's the same angle

as I did on the other side.

So two pennies under the spine

is gonna give me the proper angle.

So as you sharpen these two planes

and they start to intersect,

what's gonna happen is the very edge

is gonna start to curl over

and it's gonna create what's called a burr.

This burr or little ridge

is something that you can feel

just by touching the flat part of your knife

and running your fingers off.

And you wanna feel that burr or ridge catch on your finger.

If you don't feel that

your knife is just not sharp yet.

Depending on how dull your knife is,

this process can take five minutes,

this process can take half an hour.

So you just have to be patient

and keep feeling and keep checking for that burr.

Once I've gotten the burr to form on both sides

I'm ready to move on to my second stone,

which is gonna be the medium stone.

With the medium stone,

what I'm gonna do is actually repeat

相同的过程,会开始改善the edge.

You're gonna start to see this sediment buildup.

There's this almost like mud.

You wanna make sure you see that

'cause that sediment is basically

a mixture of the stone and the metal

that's being taken off of your knife.

This sediment's actually helping you

sharpen more efficiently

so you don't wanna wash all that off.

If your stone starts to feel dry

you can splash some water on it.

I'm gonna be constantly checking

for the burr or form evenly

from the tip, all the way to the heel.

And once I get it on one side

I wanna make sure that I get it on the other side as well.

A final step is to use this finishing stone,

and this is gonna really refine the edge

and get your knife nice and sharp.

Just a reminder, this one was the dry stone.

So the way we use a finishing stone

is by splashing water on it

before you go ahead and sharpen.

I'm gonna also use this little dressing stone,

or in Japanese, it's called a nagura stone.

I'm pre-creating a little bit of grit

so that it's gonna really help

with the polish on the knife.

At this point, your knife is fairly sharp,

we've already worked through two stones.

And when you have a sharp edge on your knife,

一把锋利的边缘so delicate

so you have to be a little careful.

A finishing stone like this is actually

[knife taps] very hard.

And if you take this sharp edge,

press it really hard against this finishing stone,

you can actually crush the edge that you just created.

The key to using a finishing stone

is to press a lot lighter

than the previous two stones.

I'm using the weight of the knife

and the weight of my hand to work on the knife.

I'm not pressing any harder than that,

but other than that, all the same techniques apply.

And even though I'm pressing very lightly

you can see the sediment's increasing.

There's much more, now that I started sharpening.

Because the stone is so fine

you're not gonna be able to feel for any burrs.

So what I like to do is take the knife,

pinch the edge of the blade, and run my fingers off.

And I wanna make sure when I do this,

I don't feel anything catch.

If I feel something catch

that means there's still a burr remaining,

so I'm gonna work just a little longer

until the edge has nothing on it.

The other thing I'm looking for

is for the edge to get really nice and shiny.

It's gonna look almost like a mirror finish

if you shine it in the light.

I usually work on a finishing stone

for five minutes, maybe 10 minutes if I have time.

But the longer you work

and get that edge nice and polished,

the smoother your edge will be.

We should be good to go with this knife.

You saw all the chips catching on the piece of paper

so I'm gonna make sure that I didn't miss anything.

So heel to tip all the way down, it's much cleaner cut.

In the beginning, this knife was really badly chipped.

It wasn't very sharp.

I used three stones,

the rough stone to grind out the chips

and set the new bevel.

The medium stone to refine

and the finishing stone to really polish the edge up.

If you were to fix this at home,

this process, from top to bottom,

should have taken around 15 to 20 minutes.

And now this knife is ready for you to use

in your kitchen and cook delicious food.

Lastly, I wanna show you guys my personal knife right here.

I've had this for 13 years,

and this knife has gone with me

to many Michelin restaurants and culinary schools.

And this knife used to be a 9.4 inch chef knife.

As you can see, this is now,

about a six inch utility knife

but it still gets it very sharp.

And the reason why I wanna show this to you

is because if you take care of your knives,

these knives can last you many, many years.

So if you feel that you're not able to fix

your own knife, that it's too far gone,

you can always send it to me at Korin,

and I'll be more than happy to fix your knives for you.