Talk to me about....kitchen knives.

[Odds]

The sharpener you've been using will scratch the edge in order to keep it sharp, although each time you do this it'll wear away the steel by breaking off particles of metal, rather than smoothing them from the blade: a bit like chipping off flakes of flint from a stone axe.
Sheffield knows a thing or two about it.
Banging your hand on the back of the knife will send a shock through the metal, making the molecules vibrate within the core of the blade. If the metal is aligned correctly they'll dance alongside each other but when you give them a shock you can create a misalignment within the metal that'll develop a hairline crack, leading to a break.
This happens all the time in aircraft as the constant changes in temperature and pressure can make the smallest fault in metal split open over time. They look huge under a microscope. Looking for Gas and Blow holes in metal is a weary task but an absolutely vital component of quality control in automotive and aircraft parts. Same principle in blades, i imagine.

 

[Mottie]

The sharpener you've been using will scratch the edge in order to keep it sharp,

Are you talking about the sharpening steel or that blade sharpening contraption? I only used that once on a different knife and didn’t like the finish so I persisted with the steel. Just a up to dozen swipes on the steel before each use.

 

[Odds]

A bit of both, really. I still have my grandfather's carving knife, worn down at the precise angle he used to sharpen it on his butcher's steel.
That blade sharpener would do more harm than good to your expensive knives.
The thing is, that knife needs an oil/water medium along the blade edge while the sharpener does his thing with the stone. I mean, you wouldn't drill into steel without lubricant to help the bit along, would you?

 

[carmanmemoranda]

I was always taught to only sharpen a knife once or twice a year or more if it is blunt, mostly from misuse.

But a steel is not always the right thing, it does depend on the blade

This Tool Does Not Actually Sharpen Your Knife. Here’s What a Steel Really Does

If you watch food competition shows, you’ll probably see a competitor or chef expertly running their knives over that steel tool pictured above. In fact, you might even own one of those steels if you have a big knife set or knife block. So do you know what that tool is? It sharpens knives...

www.thekitchn.com

 

[ReganAndCarter]

I never knew there was so much to kitchen utensils. Just bought my set of knives for £45 in a wooden block from Makro 11 years ago and used them. They're still sharp. Granted not sharp enough to slice a human hair lengthways - but sharp enough to handle all kitchen tasks.

 

[carmanmemoranda]

I never knew there was so much to kitchen utensils. Just bought my set of knives for £45 in a wooden block from Makro 11 years ago and used them. They're still sharp. Granted not sharp enough to slice a human hair lengthways - but sharp enough to handle all kitchen tasks.

for me it's not the ultimate sharpness that matter, as long as they stay sharp enough. It's the weight, feel, balance that made me decide on my set, Robert welch. I like how they feel, and cut.

 

[Mottie]

I bought them in Dec 2019, it broke yesterday, March 2023

Just to update this. Looks like I’m getting a new one. I got on to who I bought the set from and they said they would deal with it for me. Just received this email from them today:

Hi Steve
I am pleased to advise that Wusthof have agreed to send you one directly.
Please let me have all your current address contact details, including mobile number.
Many Thanks,
Kind Regards
Neil

Thats what I call bloody good customer service - especially after more than three years. I’d definitely buy from them again. https://millyskitchenstore.co.uk/

 

[Bod ...]

Going the Ideal home exhibition Saturday I'll have a good look at the knifes

 

[Justin Passing]

Yes that's good service but there's so much BS about knives it's annoying.
No you do not want a "samurai sword". For a start they go rusty, you want something stainless, on the whole.
Nor do you want something razor sharp, etc etc etc

 

[Lower]

Banging your hand on the back of the knife will send a shock through the metal, making the molecules vibrate within the core of the blade. If the metal is aligned correctly they'll dance alongside each other but when you give them a shock you can create a misalignment within the metal that'll develop a hairline crack, leading to a break.

Molecules vibrate within the core of the blade? Metal aligned correctly?

Where on earth have you heard that?

Mottie’s knife snapped because it had a stress fracture or more likely hadn’t been tempered properly after hardening, was too brittle and it flexed and snapped when he was cutting the crackling.

 

[Brigadier]

Nor do you want something razor sharp

Why would you consider a knife "too sharp"?

 

[Lower]

Why would you consider a knife "too sharp"?

If it’s too sharp the edge is very fragile.

 

[fillyboy]

Why would you consider a knife "too sharp"?

 

[Justin Passing]

That's well known fake, which you can tell if you stop the frames.

If it’s too sharp the edge is very fragile.

Yup.
QI, blades are.

If the angle is too small the blade is weaker than it needs to be; if you polish it down to the last feather at the edge, same thing.
If you try to cut a slice of something tough like a crusty roll with a razor, it'll bend and buckle the edge of the blade and snap it. (You eat the metal feather that broke off.)
-
So you need hardness, toughness, wear resistance, corrosion resistance, then the optimum in edge angles.
You get most of those by alloying, unless you want to use ceramics, which take diamonds to sharpen - not such a biggie these days. You also get the option of coating something tough(steel) with harder ceramic.
I've used glass/sapphire knives for EM prep, diamond knives, and vibratomes, a bit specialist.

 

[Odds]

Molecules vibrate within the core of the blade? Metal aligned correctly?

Where on earth have you heard that?

Mottie’s knife snapped because it had a stress fracture or more likely hadn’t been tempered properly after hardening, was too brittle and it flexed and snapped when he was cutting the crackling.

or a stress fracture caused by smacking the back of the knife?
A sharp knife should not need any force at all to cut meat.