Now that you know what you are doing, let's talk about how to do it, and that's where the edge comes in; the part of the knife that actually does the work.
You want an edge that is fine enough to cut smoothly and with minimal resistance, but stout enough to not roll or chip during the activity you are engaged in, which depend on edge geometry and stability, respectively.
Edge stability is, to a relative approximation (i.e. this steel is better than that steel), a combination of toughness and hardness, but misleading in absolute terms because toughness varies far more than hardness, and the actual mode of rolling vs chipping is different, so a direct comparison of which is more important will very much depend on the task.
Edge geometry includes various grinds, or bevels, such as Flat, Chisel, Scandi, and Hollow grinds, and the sharpening angle. Flat ground blades have no bevel, so the edge is flat all the way to the spine of the blade. The Chisel grind is only sharpened on one side, leaving one side of the blade perfectly straight. The Scandi grind is a simple bevel on each side, while the Hollow grind is concave, the edge itself is actually curved on each side. There are other grinds, such as Convex, Saber, and Compound, but these are less common in kitchen, pocket, or even hunting or camping knives than they are in axes, swords, or specialty blades.
Sharpening angle depends on the intended use and the properties of the steel; measured in DPS, degrees per side, 10-25DPS is the normal range for various knives, with 16DPS being an inflection point; lower than that, and resistance (i.e. wear) goes down dramatically; above that, edge stability increases significantly.
In practical terms, this means that a stronger (tougher and harder) blade can take a finer edge which will cut more smoothly and therefore wear more slowly than a blade made from a high wear resistance alloy that needs a broader edge to avoid chipping. This is relative to the task, of course; a high wear resistance alloy with a fine edge used carefully (i.e. always cutting straight onto a cutting surface) will hold its sharpness for a very long time, indeed.
For harder, less stable, or inexpert use, however, erring on the side of a tougher alloy with a finer edge is generally, if nothing else, easier to fix by sharpening or reprofiling than a chip in a super-steel.
Sharpening
This could be an entire article, or book, on its own (and it is), but the basic idea remains the same: If there are places on the edge of a blade that could be sharper, you can abrade material away to create a finer edge.
The devil, of course, is in the details, but here are some general guidelines:
Use an appropriate stone; a natural stone, usually made of quartz, is fine for Carbon steel blades, but even regular stainless steels will be more easily sharpened by a ceramic stone, like Aluminum Oxide or Silicon Carbide, and super-steels with harder carbides may be almost impossible to sharpen without a diamond stone.
Wet the stone. Ceramic stones use water, but most natural stones need some kind of oil; mineral oil is best, but baby oil, motor oil, even vegetable oil (although it will go rancid if left on) will work in a pinch. Do not wet diamond stones.
Watch your angle. There are different ways to do this: One is by using a felt-tipped pen or marker to cover the old edge, and make sure that you are removing all of the ink while you sharpen, which will keep you at roughly the same angle as the old edge; there are wedges with different angles which you can hold between the knife and the stone; or there are sharpening systems which let you set the angle for a consistent edge. The pull-through systems are not recommended. The ink method is also useful for determining the existing edge angle.
"Chase the burr." There is some difference of opinion on this subject, but once you understand what is happening, the answer is simple. Tests will show that "pushing" the blade towards the edge across the stone will result in a finer edge... in a given number of strokes, but it is just removing material more quickly, at the risk of damage to both the edge and the stone. Some water-cooled grindstones with firm angle guides are intended to work this way, but it is not the correct technique for any other sharpening method. A sweeping motion, down the edge (opposite from the cutting direction) and up the base to the tip will develop a fine burr.
Strop. Pull the edge lightly across either a stropping block (wood with stropping compound on it) or a piece of leather (the back of a full-grain leather belt in a pinch), several times, alternating sides. This will bend the burr back and forth until it comes loose from the edge, leaving a hard, straight cutting line.
Tools
Here are some examples of different sharpening stones and systems:
This is the system I use on my own knives; convenient, portable, easy to setup, the only issue is trying to set very fine edges on small (narrow) blades, as the clamp can get in the way of the stone.
Less portable with more features, such as preset angles (you have to use a separate angle finder on the Ruixin, although every smart phone has one built in), this is definitely a nicer piece of equipment for set use in a shop.
Stoichiometry is the measurement and calculation of the ratios of different elements in a chemical reaction in relation to their mass. For information about the composition and properties of steel, please refer to the Knife Steel article. This article is largely about how to interpret the different formulae of alloy compositions in terms of the carbides they develop.
This may seem odd to those who either never studied chemistry, or have forgotten what they did study; after all, 1% Carbon by weight is 1% Carbon, right?
Sure, but 1% Carbon, 1% Chromium, and 1% Tungsten by weight are radically different; the individual atoms of different elements have different weights, and so a gram of Carbon represents many more actual Carbon atoms than a gram of Chromium represents Chromium atoms... and chemical compositions are defined by the number of atoms of each element, not their mass.
And that is the information we need: The atomic mass of each element (i.e. how much each atom weighs), the chemical formulae for the different types of carbides that can form, and the composition of the actual alloy in question.
Note 1: For the purposes of this discussion, the differences between carbides and nitrides are largely irrelevant. This is simply about how to interpret the chemical composition of a steel alloy.
Note 2: All values are rounded for convenience; chemical processes are almost never 100% efficient in terms of each element getting where it needs to go, and the actual behavior of complicated systems like steel alloys is often difficult to predict, even for experts in the field.
Atomic Weights
These are the AMU (Atomic Mass Unit) values for the relevant issues; this is a measure of how much a mol of atoms of that element weighs.
"Mol," is a number, like "dozen" (12), "score" (20), or, "gross" (144), but a "mol" is 6.022 x 1023. A dozen grains of sand will hardly be noticeable on your fingertip; a mol of grains of sand is about 17 trillion tons. Atoms are small; write that down.
The most basic atom is Hydrogen, with an AMU of 1.07, that is, a mol of Hydrogen atoms weighs 1.07 grams (it should be 1, since Hydrogen is just a proton and electron, but the isotopes Deuterium and Tritium increase the average mass because they have one or two neutrons).
Here are the relevant elements and their AMU values:
Element
AMU
Carbon (C)
12
Nitrogen (N)
14
Vanadium (V)
51
Chromium (Cr)
52
Iron (Fe - Latin Ferrum)
56
Niobium (Nb)
93
Molybdenum (Mo)
96
Tungsten (W - German Wolfrahm)
184
There are large differences at play, here. Alloy compositions are expressed for the benefit of the actual production of steel, not its analysis, use, or design; "How much of each element needs to go in to get the result I want?" That has to be expressed in mass, weight, because that's how it is measured out in production, even if it creates some inconvenience for those of us who wish to know what it all actually means.
As a result, a given mass of Vanadium represents almost twice as many atoms as the same mass of Molybdenum (hereafter shortened to, "Moly," for convenience), which would be about twice as many atoms as the same mass of Tungsten.
Carbides
Carbides are the hard pieces embedded in the (relatively) softer steel solution, and form as crystals from the various atoms. Importantly, carbide volume is based on the number of atoms involved, not the weight, and this is why the stoichiometric ratio is so important, as it represents the ratio of mass to number of atoms for a given carbide type.
The other major factor is carbide size (refinement); being hard but brittle, larger carbides are more prone to both breaking, themselves, and being pulled out of the steel solution. Smaller carbides are both tougher and leave more solution steel in between them for overall strength.
These are the chemical formulae (element with the number of atoms in each molecule in subscript), stoichiometric ratios, and approximate hardness values for most of the common carbides and nitrides formed in knife steels, along with the base allotropes (crystal formations) of the steel solution, for reference:
Carbide
Stoichiometric Ratio
Hardness
FexC Austenite
-
250V, 23Rc (Min)
FexC Martensite
-
750V, 63Rc (Max)
Fe3C Iron Carbide (Cementite)
14:1
950V, 68Rc
Cr23C6 Chromium Carbide (cubic)
14:1
1000V, 69Rc
MoxC Molybdenum Carbide
16:1 - 48:1
1300V -1900V
Cr7C3 Chromium Carbide (hexagonal)
10:1
1400V
CrN/Cr2N Chromium Nitride
3.7:1 / 7.4:1
1600V
CrV7C3 Chromium-Vanadium Carbide
1.5:10:1
1800V
NbC Niobium Carbide
8:1
2400V
WC Tungsten Carbide
15:1
2600V
VC Vanadium Carbide
4.25:1
2800V
Let's use Chromium Carbide (hexagonal) as an example; it is both commonly desirable, both from being hard and giving other benefits, and easy to deal with mathematically, since the ratio is 10:1 (9.9:1, actually, but rounded to 10).
What this means is that those 7 Chromium atoms weigh 10 times as much as the 3 Carbon atoms; 1% Carbon by weight would ideally want to use 10% Chromium by weight. It doesn't, since it will always tend to form some of the carbides you don't want, if possible, but this tells you, for example, why D2 steel, with 12% Chromium and 1.5% Carbon, is not stainless; there's not enough Chromium left over from forming carbides to make the steel solution reasonably corrosion resistant.
Vanadium carbides are among the most desirable, for both being the hardest generally found in steels and having a very low stoichiometric ratio.
Moly carbides are misleading, since they usually form hybrid carbides with other elements, which are both varied and difficult to predict, and the stoichiometric ratio is very high.
Niobium carbides are interesting because they are both very hard, and form easily in most alloys, with a quite moderate stoichiometric ratio.
Nitrides are quite hard with a low stoichiometric ratio, and so have a powerful effect on wear resistance, but since Nitrogen is a gas, it is hard to get high fractions in an alloy.
You may notice that the hardness scale only uses Vickers for most carbides; this is because the Rockwell scale becomes misleading at higher values, with effective upper limits ranging from 65 to 80 (roughly 800 to 1800 Vickers) depending on the standard. I have chosen to stop at 69Rc, mostly for convenience of comparison to other sources of information.
Discussion of Selected Knife Steels
The following is an analysis of the composition of most commonly available knife steels, with recommendations below that I earn a small commission on, which is the only profit I receive from this project (there will never be any ads, and I will only ever accept sponsorships for items and brands that I fully believe in).
Please buy through the link if you were going to, anyway, so I can make a little money at no cost to you! And in either case, I hope you enjoy and appreciate the work.
Carbon Steels
1070 (0.7C)/1080/1084 (0.8C)/1095 (.95C): With no other carbide forming elements, these steels only ever form Cementite, placing an upper limit on their wear resistance and potential hardness, but they are durable and easy to sharpen, excellent qualities in survival knives.
5160 (0.6C 0.8Cr): The slight amount of Chromium is not enough to form significant carbides, so wear resistance is not improved, but the strengthening effect in the solution steel along with relatively low carbide volume makes this a very tough steel.
52100 (1C 1.5Cr): Still not enough Chromium to form significant non-ferrous carbides, the carbide volume is significant. This steel combines good toughness and hardness.
A2 (1C 5Cr 2V 1Mo 0.3Ni): The 5% Chromium could theoretically use about a third of the Carbon to form Chromium carbides, but of course that never happens, but this is a fairly tough steel with decent carbide volume.
D2 (1.5C 12Cr 1V 1Mo): This alloy has pretty high carbide volume, a lot of which is Chromium carbide for solid wear resistance, it also hardens very well, if not being the toughest steel available.
M4 (1.4C 4Cr 4V 5Mo 5.5W): Now we are getting complicated; that looks like a lot of alloy, and it does wind up with a good bit of VC, MoC, and WC, but it actually has a larger fraction of Iron carbides than D2; Molybdenum and Tungsten carbides have such high stoichiometric ratios, they don't contribute to carbide volume as much for the same mass, and also form in different temperature regimes.
3V (0.8C 8Cr 3V 1.3Mo): A little more straightforward, this is a modern steel, which is reflected in the better balance of Carbon to carbide-forming elements, resulting in a very tough steel with decent carbide volume, much of which is Chromium and Vanadium.
Cruwear (1.1C 8Cr 2.4V 1.6Mo 1.2W): A modern alloy, it gets a good bit of Chromium and Vanadium carbide with significant carbide volume, and still manages to score well in both toughness and hardness.
420 (0.15C 13Cr): The original stainless steel, it has extremely low carbide volume, but a lot of it is Chromium, so the wear resistance is actually better than many plain Carbon steels.
420HC (0.5C 13Cr 0.3V 0.6Mo): The modern update of the classic, the increased carbide volume gives improved wear resistance, and while they are still mostly Chromium carbides, the Vanadium helps refine the carbide size for high toughness while the Moly helps retain corrosion resistance.
440C (1.1C 17Cr 0.75Mo): The last of the classic stainless steels still in common use for knives, this steel has a significant carbide volume, with quite a bit of Chromium carbide.
154CM (1.05C 14Cr 0.4V 4Mo): Developed from 440C, this steel does not actually develop Moly carbides, leaving only Chromium and Iron carbides, but the significant carbide volume gives good wear resistance, while toughness and hardness are moderate.
14C28N (0.62C 14Cr 0.1N): A modern Nitrogen steel, it forms hard nitrides in addition to Chromium and Iron carbides for decent wear resistance in a very tough alloy.
8Cr13MoV (0.8C 13Cr 0.1V 0.15Mo): A modern Chinese alloy developed from 440A, with variations mostly involving the Carbon content, this is a decently tough steel with a moderate carbide content, only slightly refined by the Vanadium addition, it's most salient feature is its accessible price point.
LC200N (0.3C 1Mo 15Cr 0.5N): Another Nitrogen steel, this one biased towards extreme corrosion resistance, which it does well. The low carbide volume is enhanced with Chromium nitrides, but the overall volume is still fairly low, resulting in only moderate wear resistance, but high toughness.
Nitro V (0.68C 13Cr 0.1V 0.11N): Another Nitrogen steel, this is a very balanced alloy. The moderate carbide volume and slight nitride addition result in a decently tough and hard steel with moderate edge retention.
VG10 (1C 15Cr 0.2V 1Mo 1.5Co): A common Japanese knife steel, it has a decent carbide volume with a lot of Chromium, and the Cobalt addition increases hardness for an excellent cutting edge.
X50CrMoV15/1.4116 (0.55C 15Cr 0.2V 0.8Mo): An almost ubiquitous German knife steel, its moderate carbide volume includes enough Chromium for respectable edge retention, while its low hardness allows reasonably easy sharpening.
S90V (2.3C 14Cr 9V 1Mo 0.4W): One of the earlier powder metal alloys, it stretches the definition of the word, "steel," by having more than 2% Carbon content, which should technically make it Cast Iron but for the sinter-forging process, and with a very high carbide volume (>20%), only the extremely high Vanadium fractions keeps the carbide size fine enough to not be unacceptably brittle. Only moderately hard, the wear resistance is of the highest order.
S30V (1.45C 14Cr 4V 2Mo): A 21st century steel, this was one of the first alloys specifically designed for knives. A powder metal steel, the high carbide content is biased towards Vanadium carbides, although significant Chromium carbides are also formed, resulting in good wear resistance, although decidedly mediocre hardness and toughness.
S35VN (1.4C 14Cr 3V 2Mo 0.5Nb): An evolution of S30V, the Niobium addition is rather small, but powerful, and helps make up for the slightly lower carbide content in terms of wear resistance, allowing improvements in hardness and toughness.
S45VN (1.48C 16Cr 3V 2Mo 0.5N 0.5Nb): A further evolution of S35VN, this alloy adds Nitrogen to develop higher hardness at the cost of toughness from higher carbide/nitride volume.
Magnacut (1.15C 10.7Cr 4V 2Mo): The current king of the hill, this ultramodern powder-metal alloy was precisely engineered to balance toughness, hardness, and wear and corrosion resistance with precise alloy fractions for ideal carbide type, volume, and refinement. It brooks no equal in terms of overall performance; in any given attribute, you can find a superior alloy, but only at the cost of one or more other attributes, and to a greater degree.
Magnacut was first released to the market in 2021; S45VN in 2019; S35VN, 2009; S30V, 2001. In absolute terms, Magnacut is about twice as strong as S30V, with similar wear resistance and superior corrosion resistance. In 20 years, the best knife steel available became twice as good.
What will we see in another 20 years? How much better will our materials become? What does that even mean?
Astute students of modern mythology, especially that surrounding knives and steel, may notice that my ratings and comments do not always line up with other available sources of information, despite my claims to have drawn from several of them, and wonder about the discrepancy.
The short answer is that I am approaching the question from the "opposite" side; most guides to knife steel are focused on the production side of the equation, i.e. "How do I balance the properties I want against the theoretical constraints that I know and think I understand," or even, "Which steel should I pick for a given task," which are perfectly valid approaches to the situation.
This project is about the end user; what are the actual, absolute properties of this item in relation to another variation, regardless of the theoretical considerations or ideal balance of properties for a given task. You have a knife; what do you need to know about it to use it safely and effectively for your current needs? We don't always get to choose, and the choices are not always straightforward.
The long answer will be an article of its own.
As an Amazon Associate I earn from qualifying purchases.
“Would you happen to know what month of the year it is?”
“No, I… I truly wouldn’t. I’m sorry pilgrim.”
- Jeremiah Johnson and Bear Claw Chris Lapp, Jeremiah Johnson
A true mountain man has no need of a watch, his schedule is dictated by daylight and season. The order that civilized man imposes on the world - time, space, rights - are meaningless to someone who does what he will, when he will, regardless of what anyone else thinks of the matter.
They have to live in the mountains for a reason, though; a city, a town, even a village composed of such individuals would rapidly descend into chaos. Several years ago, a group of hardcore Libertarian Party activists all moved to a town in New Hampshire, taking it over by outnumbering the original residents, electing themselves into positions of power, and dismantling the local government in the name of minimalist interventionism.
They wound up being overrun by bears; they wanted to be Jeremiah Johnson, but didn't have the chops to back it up.
Now, this is not a political piece, and this should not be taken as either a rejection of government minimalism as a practical philosophy or as an endorsement of uncritical support of authoritarianism.
This is about watches.
Wait, What?
Watches are symbols, representing order imposed on time. The nicer the watch, the more money spent on it, the more you appear to value your time. Different kinds of watches suggest how you spend your time. Size, shape, material, colors, all suggest details, telling you something about the other person... or telling them what you want them to think about you.
Rolex is considered a luxury brand, but their claim to fame is the "Oyster" case, hermetically sealed against dust and water while still allowing adjustment. "My time is important enough to spend extra money to make it slightly more accurate; the gold and diamonds are to make sure you know it."
Timex, "Takes a licking and keeps on ticking," made their reputation on physically tough, accessibly-priced watches. A "working man's" accessory, it suggested a hard-nosed, no nonsense approach to the world.
Seiko and Casio are Japanese brands who revolutionized watches, Seiko with automatic and quartz watches, Casio with digital and multifunctional watches. These became something of a symbol of progressivism, Casio somewhat more active and casual, Seiko more formal, but both suggesting an openness to new ideas.
The "Swatch" brand from the 1980s was an interesting example, as they were explicitly inexpensive and toy-like, suggesting frivolity and a carefree, lackadaisical approach to time. They still make watches, and are still mid-lower tier fashion items, but are significantly more restrained than their earlier models.
Even then, though, it suggested some level of cooperation and organization; "Synchronize Swatches!" was the catchphrase of an otherwise forgettable high school sitcom as they began their planned hijinx and good-natured rivalry with (but ultimately subservience to!) the relevant authority figures.
Modern Watches
Many of us thought that watches were relegated to fashion items with the widespread adoption of the cell phone; why do we need a separate tool to track time when our phone does that, and many other things besides?
Well, if it is features that you want, Capital will provide! Beyond the calculator and stopwatch functions, various gadgets have been added over the years, up to the ability to connect to your cell phone and access its features without removing from your pocket. Health monitor functions, from pedometers to heart, sleep, and stress disorder detection, are commonly available, and some smart watches even support video calling.
Here are some examples of different kinds of watches, with suggestions:
"Four hundred years previously, the state of mechanical knowledge was far beyond our own, and was advancing with prodigious rapidity, until one of the most learned professors of hypothetics wrote an extraordinary book (from which I propose to give extracts later on), proving that the machines were ultimately destined to supplant the race of man, and to become instinct with a vitality as different from, and superior to, that of animals, as animal to vegetable life. So convincing was his reasoning, or unreasoning, to this effect, that he carried the country with him and they made a clean sweep of all machinery that had not been in use for more than two hundred and seventy-one years (which period was arrived at after a series of compromises), and strictly forbade all further improvements and inventions." -Samuel Butler, Erewhon
A quick glance at AI-generated art should disabuse us of the notion that our technology will physically enslave us; the impressive pattern matching and syntax skills demonstrated by our machines is inherently limited by their complete and total lack of semantic reasoning. Yes, it can be guided (although I have not done so for demonstrative reasons), but that is the point: It requires a human master; it literally cannot master us, it needs us to master it, or it has no function or purpose.
At the same time, "Artificial Intelligence," is a tool, an extension of our natural abilities, and like all tools, in using them we remove ourselves, step-by-step, from our full, natural abilities. Imagine being stranded, alone, at night, lost in the forest, with no cell phone, pocket knife, flashlight, compass, map, shoes, clothes... our distant ancestors would think nothing of the situation; that was their daily lives, and they were comfortable and confident in that environment.
Should we reject shoes, because we might need to walk without them, and our feet will not be tough enough? Are we enslaved by our shoes? The ideas are absurd. The danger is in believing that our technology is capable of more than it is, in trusting AI to tasks which it is not suited, depending on it in ways that will result in harm.
Isaac Asimov developed his Three Laws of Robotics in order to protect humans, but clearly, they could not be trusted to properly interpret those laws. "A robot may not injure a human being or, through inaction, allow a human being to come to harm," but what is the difference between an artificially-intelligent robot and a human being? What constitutes inaction or harm? Will they go around taking cigarettes out of people's mouths, or force them to exercise?
The first human to lash a sharp rock to a stick almost certainly injured themselves with it; the leading cause of death for children in 19th century America was falling off a wagon, but then, until the widespread adoption of the automobile, the street was one of the safest places for children to play. The function and purpose of firearms is widely displayed in media, from movies to television to video games, but the lack of hands-on firearm education leads to many injuries and deaths from misuse.
If we will not show due respect and establish proper channels of education for such widespread and clearly dangerous objects, what are we going to do about the more nebulous threats of Artificial Intelligence? An examination of the proposals to deal with social media and the Internet should give us a clue: Don't educate people, don't mitigate the harms, but use the law like a hammer and the problems are just gaps to be nailed down tight.
That never worked for guns; that never worked for speech; and that won't work for AI. We need a new, social understanding of the problems, and a better system for providing the necessary education to safely use technology.
