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Forming an Edge

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74 pointsvisviva29 comments

I don't think we need to descend to this level of mysticism when discussing knives.

If you want a knife that is a carefully crafted beautiful object, hand-made by a craftsman with a long legacy and great skill, then feel free to buy a Japanese or handmade American (or whatever) knife. It'll be beautiful. You'll likely love using it, and think about the story often when you do. It's a great thing.

But if you want a knife that's going to be sharp, durable, safe, and efficient, don't feel like you need to believe the hype about steel, or the hype about craftsmanship. Especially don't believe that you need to accept either a knife that is going to require careful maintenance, or a knife that's "soft" or "gummy".

On nearly any objective measure - edge retention, hardness, toughness, wear resistance, corrosion resistance, etc - there are modern steels that significantly outperform low-alloy carbon steel. More specifically, there are modern steels that are significantly closer to any reasonable Pareto frontier of knife steel than low-allow carbon steel (Japanese or not). Many of these steels are corrosion resistant, if not outright stainless. Particle metallurgy steels like S35VN or Magnacut or S30V, while expensive, have incredible properties for kitchen knives of many styles. There are even modern steels like S90V that are so wear resistant that sharpening them without machines can lead to madness.

Low-allow carbon steel (like the mythologized Japanese steels) are significantly easier to work with traditional techniques, and therefore frequently chosen by the people who practice those techniques. That workability comes to come with significant tradeoffs (including corrosion resistance, which is important for both edge retention and every day usefulness).

This article also isn't super clear about sharpness. There's a lot more to edge geometry than is presented here. In fact, edge and bevel geometry is easily more important than steel. Depending what they are cutting through the thickness of the edge may matter, but often the thickness just behind the edge matters just as much.

If you're interested in getting into knives and want to avoid the mythology, I highly recommend Larrin Thomas' book "Knife Engineering". It's a great read on the things that matter, and the tradeoffs in the space.

A while ago I started making my own knives. Now every kitchen knife I own is one I made myself, including heat treating and other possibly mythological processes. On that journey, I've learned a huge amount of respect for the incredible craft that is knifemaking, but also a lot of skepticism for the assertions that connect knife craft techniques to knife performance.

These days I sharpen on a Tormek wet grinder, and touch up with a 1000 grit "splash and go" stone. Sharpening can be an entire hobby of its own, but again you don't need to buy into the mythology to get a knife that's extremely sharp.

When I worked in food service the knives were rotated weekly and came back super sharp. It was really nice- a really sharp knife, properly handled, is a real pleasure to use.

At home, I'm lazy and never have my knives sharpened- yet my one high quality knife is still pretty good after 5+ years of not being sharpened (it no longer cuts skin when drawn across it lightly). I did learn a trick- for most situations, a scalloped knife with with light serrations slices through tomatoes and never needs sharpening.

Farmers market by me sharpens knives for like a dollar a pop, bring everything there a few times a year

To anyone considering getting into knife sharpening:

Usability matters more than perfection. If you're the type of person that would only sharpen knives once a year because it takes half hour to set up your sharpening rig and sharpen your knife, get an electric sharpener instead - takes about 15 seconds. Yes, it's not glorious or Instagram-pretty, but it gets the job done well.

For hand sharpening - look up micro-bevels. They speed up sharpening time considerably (still not as fast as electric sharpeners though).

Maintenance is more important than sharpening - and maintenance should be done almost every time you use the knife and should just take a minute.

> only sharpen knives once a year

If you have a decent quality knife you do only need to sharpen it once a year + give it a few swipes on a honing steel every time you use it.

Hell no. It dépend a lot of the angle of the edge, the steel hardness and how and where you use it. I hone mine every 3 to 4 weeks, and I’m gentle with my Global chef’s knives

I hone mine every time I use it with a steel. Honing is not the same thing as sharpening - op was talking about sharpening.

(For those curious - the sharp edge on the knife tends to bend over time, which makes it worse at cutting. Running it over a honing steel helps to straighten that bend out but doesn't actually remove metal from the blade. The actual edge will stay sharp for much longer and so you only need to properly sharpen (with a whetstone or if you hate your knives one of those awful swipy wedge things) a decent knife once every 6 months - a year.

Sorry, I meant sharpening. Edge dull, even with a high rockwell hardness. And then you will have micro chipping and so on happening… honing every time is the foundation.

My chef's knife is a Elephant-brand carbon-steel sabatier. It gets five strokes each side on a steel, every few times I use it. The steel is ancient and worn; and I'm sure it's never been near carbide or diamond.

Every few months it gets a few strokes on each side on a coticule. I have a coticule because I got into shaving with a straight razor. I have a leather strop for the razors (it's never seen any kind of paste!) My understanding is that stropping is to re-align the edge of the blade, which tends to 'flop over' in use. I don't strop kitchen knives; I don't think the edge is thick enough to flop over. I only strop razors.

Neither stropping (on clean leather) nor steeling should be removing metal; no metal or abrasive particles should be produced, and it's perfectly safe to do it in the kitchen. Sharpening with the coticule does remove metal, but the particles are captured in the watery sludge, and don't escape as dust.

[Edit] My chef's knife is not Elephant; it's Richardson Steel of Sheffield (from before they sold out). I bought an Elephant paring knife, though, and Elephant chef's knives for each of my kids.

Another side of this... if you're on a budget, you can turn a crap knife into a pretty serviceable knife with a very basic setup. I've got a pair of santokus that were about $20 each (one bigger one for meat and large veggies, smaller one for small veggies) and a set of 3 progressively finer sharpening stones from Princess Auto (the Canadian equivalent to Harbour Freight). About once a month I take the two knives and give them about 5 passes on each side, with the bevel set basically at the angle I get if I have a finger in between the spine and the stone. Takes about 45 seconds and they get sharp enough to pass the tomato test.

They don't maintain their edge, but I've had fantastic slicing for a decade now for $50.

Yep, the distinction between crappy knives and good knives is generally more about how long they hold an edge for rather than how sharp that edge is.

Victorinox make knives that are good and cheap though. They're the only brand I know of at that price point that I really wouldn't mind using instead of something quite a bit more expensive like Global.

Assuming a certain baseline quality of steel, the most important thing in a knife is how comfortable the handle is and whether the balance/weight is right for your particular taste and grip.

I've also found Ikea knives to hold an edge as long as my Victorinox knife. They are only stainless, but the alloy they use seems to work quite well.

Sticking with the usability theme -- get a leather strop and some stropping compound! It's so much easier to pass all the sharpness tests and keep an edge on a knife if you use a strop. It doesn't require as much precision due to the way the leather molds to the surface of the edge. Quick, easy, and effective assuming you already have a decently formed edge.

PSA don't sharpen or strop in your kitchen- it's a dirty business. You will have invisible metal shavings (chromium, nickel) that make it into your food and strop compound is made of aluminum oxide and chromium oxide.

> If you're the type of person that would only sharpen knives once a year because it takes half hour to set up your sharpening rig and sharpen your knife, get an electric sharpener instead

This is an obsolete dichotomy. There are excellent modern low-porosity stones that you can get wet and use immediately. For example, resin bonded diamond (e.g. CGS, Venev, Naniwa Diamond), Shapton Glass (unspecified “ceramic”), or diamond-in-nickel (DMT).

The idea of a long progression of expensive stones seems to be almost entirely a myth — there seems to be no actual benefit, and possibly quite a bit of wasted time and increased chance of entirely failing to get a good edge, if you use a zillion different grits. A cheap coarse stone or two and one (expensive) medium-fine stone is plenty, and you won’t touch that coarse stone if your knife is already in decent shape. Throw in a strop loaded with a decent abrasive and you can maintain your knife in a minute or two.

(I use a cheap balsa wood strop loaded with 1 micron CBN suspended in water. Total setup time to strop a knife is however long it takes to get it out of a drawer. WEAR A REAL MASK and work outside while applying the CBN — I seriously doubt that inhaling a fine mist of tiny minerals is a good idea.)

I used to spend hours with all the fancy stones and ceramics and such.

Anymore I just sharpen everything on my belt sander. Takes only a few seconds, and gets you about 80-90% as sharp as the fancier methods.

It may look simple in the diagrams and videos but sharpening is a tough skill to learn and then to master. One thing I learned through multiple woodworking classes is to avoid Japanese waterstones. They are beyond fiddly requiring regular reflattening in swarfy water every couple of dozen strokes of the tool. I spent more time doinking with the stones than actually sharpening. My diamond stones at least let me focus on developing the skill vs. fettling the tool AND then developing the skill. Maybe someday I'll shave the hair on my arms.

As with so many things, Paul Sellers makes it look Bob Ross easy.

https://www.youtube.com/watch?v=GN4yr7vp4I4

https://www.youtube.com/watch?v=Ki8tt-VjwqI

Edits for clarity and links.

Funny anecdote: My mom prefers dull serrated knives. This is because she cuts ingredients over the stove and in her hands - she literally holds the tomatoes and diced them over the pot. A sharper knife doesn't enable this technique so she hates chefs knives.

I also sometimes do this (although not with tomatoes). But my knife for this is very sharp and hook-shaped (I think the english word is "turning knife"). Only thing you have to pay attention to: when cutting "against your thumb", never press your thumb into the knife, otherwise things will get bloody. The technique that works best imho is to e.g. hold a carrot in one hand, knife in the other, thumb fixing the carrot and knife edge cutting in a rotating motion around the carrot's axis beside your thumb.

For those who like sharp knives, but don't want to persue a doctorate in the matter, may I humbly suggest the Catraphone: https://www.catra.org/sharpening-products/catrahone-domestic...

The rabbit hole of knife sharpening goes incredibly deep. But if you're just looking to cut food in your own kitchen, the vast majority of it is overkill. Professionals seem to make a bit deal out of knives, but many professionals use their knife as much in one day as a home cook does in one year.

Most expensive knives are made out of difficult to work with metals. They keep their edge for longer, but:

1 They're harder to sharpen. The longer the knife can hold its edge, the longer it takes to grind out that edge. Higher end knives typically require diamond to sharpen at a reasonable pace, or at all.

2 They chip easier. Just like like glass used for smartphone screens, the better it resists scratches, the easier it shatters. High end knives, if they're not thick, need to be carefully handled, or you'll get a surprising number of nicks and chips in the edge. A sign someone doesn't handle their expensive knives properly is if the pointy tips are chipped off.

3 They rust easier. High end knives often use metals with higher carbon and/or lower chromium content. I learned this the hard way, as I air dry all my dishes, and knives with even 440C will rust if you don't towel dry them after washing. Ultra hard knives that use non-stainless steel need to be kept covered in oil to prevent rust.

If you're just getting into cooking, you don't need much. Mercer Culinary is the go to brand for culinary school students. Their Millennia line comes sharper, harder, and more durable than any grocery store knife, while still being highly rust resistant.

If you want to use a whetstone, avoid the soft "beginner friendly" stones. They need to be soaked in water for like half an hour before you can use them, and they wear out very quickly. The only reason they exist is because they provide more feel or feedback. Instead, I'd recommend a Shapton basic 1000 grit. It's a hard and durable stone that cuts fast, only needs a splash of water, and leaves you a very usable edge. Lower grits are for re-profiling the blade, such as if you've got nicks or chips. Higher grits are for polishing the edge, if you want to shave with it or something.

If using a whetstone seems too difficult, and you want an easier to use, but slower option, look into a Spydero Sharp Maker. I run my knife one pass through this thing before I use it, and it keeps the edge consistently sharp. I use my Shapton whetstones for when I'm sharpening my friends' knives.

Learn to slice instead of just ramming your knife straight down into the cutting board. Of course, some things require a chopping motion, but slicing is safer, and your knife edge will last longer.

Nothing about this article really has to do with a knife. :)

thanks for submitting it.

Off topic, honing keeps the edge from needing to be reformed often

Roughly, edges can roll over, break off, or wear down. Honing helps with the first, but not the other two. Which one happens depends on geometry, steel, and what you've been cutting.

Not quite. Edges can break from excessive rolling and bending which is the usual mode if the steel isn't over-hardened (Excessively hardened steel will not roll over, only break, and is usually impossible to sharpen). You can get breaks from hitting something hard like another metal or ceramic surface, but those accidents you cannot fix with honing. They should be rare if you pay attention. Wear can also be fixed with frequent honing if your hone is either hardened steel (usually the ones with the very fine structures and the dull darker surface) or diamond surfaced, because both are mildly to very abrasive.

tl;dr A meditation on how people achieve knife sharpness by (former? chef) TW Lim. This touches on steel heat treatment and grinding angles. Poetic language. Hosted on ghost (mentioning this in case you are allergic to subscription websites).

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