A lot of people these days seem to think that spending $300 on a knife automatically makes that a superior knife. As though somehow price and value are intrinsically tied. As though they have some sort of correlation! Au contraire my dear, simple people from nowadays. Au contraire. Just like cameras, hands, and family, the best survival knife is the one you’ve got with you. That means a sharpened spoon handle, in the absence of all other knives, IS the best survival knife. You can’t very well use what you don’t even have. But what if you’re given the choice? After all, preparation is 95% of any good survival plan. Given the choice, you’re going to have a variety of good knives from reputable manufacturers to choose from. What about the inevitable anxiety from being overwhelmed by choice? Who is the best knife maker? What’s the best metal to make a knife from? How should the blade be ground? Which thunder god should you battle on the mountain peak to attain your level 100 attack?? Relax. All of these are fair, natural questions that everyone asks at some point in their lives (especially the one about battling a thunder god). Before we get ahead of ourselves, let’s take a look at what makes a survival knife.
What’s A Survival Knife Anyway?
Survival knives are set apart from other types of knives by their robust designs and strong materials. They are not well suited to specialist tasks – you might not enjoy using your survival knife in the kitchen as its short, thick blade doesn’t lend itself well to fine work. You can’t sliver your sashimi or julienne your carrots. That’s not the domain of the survival knife anyway – it’s stuff a kitchen knife can do. What a kitchen knife can’t do though, is put up with a month of abuse in the forest. A survival knife’s blade won’t chip if you butcher a wild pig with it. If it’s made well enough, a survival knife won’t even flinch at taking a branch off a tree to kindle a fire for your roasted wild pig. A survival knife is the absolute generalist tool. Not really perfect at anything other than making two pieces out of one, but good enough to replace most of your toolbox in a pinch. The sharp tip can fit into the head of a screw, so if you need your knife to be you screwdriver it can be. The pommel might be the tang, flattened out to form a butt on the handle. This can be a hammer in your hour of need. The elevator doors might be jammed shut but by gum, you’ve got your survival knife handy. Its thick blade will shrug off being used as a pry bar. At the end of the day you’ll probably wonder what your survival knife can’t do (hint – survival knives are awful at returning your love).
Characteristics of Steel
There’s a lot of hype to cut through when beginning to research a type of steel that you’d like your knife made from. Manufacturers often try to pitch their products as being made from super steels or magical alloys. Essentially, all steels manage a couple of compromises – you get to choose between hardness and toughness, and between corrision resistance and wear resistance. The harder a steel is, the more brittle it is and as a result, the less tough it is. Tougher steel will lose a bit of hardness but survive harsh impact without chipping or shattering. In stainless steels, chromium is mixed into the steel alloy to stop rust. The more chromium, the better your knife will stand up to the weather. The other side of this though, is that chromium makes steel softer. High chromium blades won’t rust, even if their whole operating life is in the ocean. They will lose their edge easily though, which makes everyone sad face and cry.
A summary of the characteristics of a knife blade are strength, toughness, wear resistance, corrosion resistance and edge holding.
HARDNESS / STRENGTH:
The ability to take pressure and not permanently deform. Strength and hardness are directly correlated ; the harder the steel, the stronger it is. Hardness is measured by the industry standard Rockwell Hardness C scale, which is also known variously as the Rockwell scale, HRc, ect. Steel that has been over-hardened may be brittle in action, as it can lack the flexibility needed to survive the knocks of work. Premium knife steels are hardened to 57 – 62 on the Rockwell Hardness C Scale.
TOUGHNESS / DUCTILITY:
Supports impact without damage. Toughness is important for tasks like chopping and any time the blade hits harder impurities in any material. Generally speaking as hardness increases, strength also increases but toughness may decrease. Toughness and hardness are somewhat in opposition to each other, increasing or decreasing in the same proportion as the other increases or decreases. Different heat treatment methods can give steel the same hardness, while leaving it with different amounts of toughness, corrosion resistance, and wear resistance.
The quality that allows a blade to withstand abrasion. When a steel alloy is first melted together, the chromium and carbon atoms join to form chrome carbides. These are very hard particles in the steel. The quantity, type, and distribution of chrome carbides within the steel determine wear resistance. Steel can be compared to concrete with stone aggregate mixed through it. The steel matrix behaves in the same way as cement, suspending the carbides like the stones in concrete. The cement in concrete wears away over time, exposing the hard stones below the surface. These harder stones wear much more slowly than the cement, just as the hard carbides in steel wear away slower than the surrounding steel.
The ability to withstand rust-oxidation is often a priority. Corrosive elements, like saltwater, acid in certain types of foods and micro-oxidation lead to edge loss in a short amount of time. “Stainless” cutlery steels, are defined by Chromium content.
A function of wear resistance, strength, toughness and resistance to corrosion. Wear resistance becomes more important for edge holding when very abrasive materials, such as carpet or rope are being cut. Strength becomes important in whittling hard wood. Corrosion inducing materials affect the edge most quickly.
ABILITY TO TAKE AN EDGE:
Enhanced by finer-grained steels. These sharpen more easily, becoming sharper than coarse-grained steels. Vanadium is used to enhance grain.
While the above characteristics and qualities of knife steel may seem separate and distinct, they can be viewed more simply in these spectra.
The two spectra aren’t meant to be seen as connected to each other. I just wanted a simple way to display the trade-off you face. What you gain in wear resistance, you will lose in corrosion resistance. What you gain in toughness, you will lose in hardness. The converse is true as well. What you cannot have is a blade that is purely tough while at the same time extremely hard. In the same way, you won’t find a magical blade that has the highest wear resistance at the same time as having ultimate corrosion resistance. The materials used in the steel alloys that produce these desirable characteristics oppose each other’s functions. Because everything outside of managerial corporate-speak exists only as a 100% or less value, the more we add of one material, the less room there is for the others. So, what materials go into a modern survival knife?
To understand the construction of any knife, some metallurgical education is necessary. Don’t worry – it won’t hurt. All steels, no matter how fancy, come back to iron and carbon alloyed together. This is a product mankind has been making for at least 25 centuries. Some knife makers swear by steels that were perfected in world war 2, some say that Damascus is the alpha and omega, while others are dead set on some bleeding-edge alloy that was only prototyped this week. It can be a matter of taste, and everyone’s experience and needs differ slightly. But in the end what we need to remember is that this isn’t gene-splicing or space travel. It’s a technology thousands of years old, and there aren’t that many ways to make it novel. It’s iron, and carbon, in a fire.
Let’s take a moment to examine the function of the raw elements used in various types of steel.
- Carbon – This ingredient is essential to steel’s creation; all steel will have some amount of carbon. It is the most important hardening element, but as it is added it can reduce the toughness of the material. Carbon reduces the amount that the knife will wear over time. So, the amount of carbon in the blade tells you a lot about the quality of the steel. Low carbon means there is (.3% or less), medium has between (.4-.7%), and high is (.8% and above).
- Chromium – Combats corrosion. Stainless steel knives will have chromium as a major ingredient, typically at a minimum of 12%. Chromium will also increase the strength of a knife, but adding chromium in large amounts decreases toughness.
- Cobalt – Strengthens the blade.
- Copper – Combats corrosion.
- Manganese – Hardens the blade. If added in high quantities it can increase brittleness.
- Molybdenum – Maintains the steel’s strength at high temperatures.
- Nickel – Adds toughness.
- Nitrogen – This element is sometimes used as a replacement for carbon in steel.
- Phosphorus – Improves strength.
- Silicon – Increases strength. Also, removes oxygen from the metal while it is being formed.
- Sulfur – Increases machinability but decreases toughness.
- Tungsten – Increases wear resistance.
- Vanadium – Increases wear resistance and makes the blade harder.
Survival Knife Blade Types and Designs
The most important part of a survival knife’s design is that the blade and handle should be formed from a single piece of metal with no joints or welds. The handle should not be a separate part of the knife. This is called a “full tang”, and it is essential to the design of a survival knife. The full tang means that the knife has no weak points. If you were to hammer on the back of the blade as you baton through a log, or pry a door open, the knife can take the stress. If the handle is attached to the blade via any other means, or the tang doesn’t extend to fill the entire handle, this is a point of weakness on the knife. For this reason, you can feel safer keeping a full tang survival knife as your primary knife, rather than a folder or cheap partial tang knife.
There are a variety of knife blade shapes; some of the most common are listed below.
1. A normal or straightback blade has a curving edge, and flat back. A dull back lets the wielder use fingers to concentrate force; it also makes the knife heavy and strong for its size. The curve concentrates force on a small point, making cutting easier. This knife can chop as well as pick and slice.
2. A curved, trailing-point knife has a back edge that curves upward. This lets a lightweight knife have a larger curve on its edge. Such a knife is optimized for slicing or slashing. Trailing point blades provide a larger cutting area, or belly, and are common on skinning knives.
3. A clip-point blade is like a normal blade with the back “clipped” or concavely formed to make the tip thinner and sharper. The back edge of the clip may have a false edge that could be sharpened to make a second edge. The sharp tip is useful as a pick, or for cutting in tight places. If the false edge is sharpened it increases the knife’s effectiveness in piercing. The Bowie knife has a clipped blade and clip-points are quite common on pocket knives and other folding knives.
4. A drop-point blade has a convex curve of the back towards the point. It handles much like the clip-point through with a stronger point less suitable for piercing. Swiss army pocket knives often have drop-points on their larger blades.
5. A spear-point blade is a symmetrical blade with a spine that runs along the middle of the blade. The point is in line with the spine. Spear-points may be single-edged (with a false edge) or double-edged or may have only a portion of the second edge sharpened. Pen-knives are often single-edged, non-spined spear-points, usually quite small, named for their past use in sharpening quills for writing. Pen-knife may also nowadays refer to somewhat larger pockets knives which are often drop-points. Some throwing knives may have spear-points but without the spine, being only flat pieces of metal.
6. A needle-point blade is a symmetrical, highly tapered, twin-edged blade often seen in fighting blades, such as the Fairbairn-Sykes commando knife. Its long, narrow point offers good penetration but is liable to breakage if abused. Although often referred to as a knife, this design may also be referred to as a stiletto or (slender variety of) dagger due to its use as a stabbing weapon albeit one very capable of slashing as well.
7. A spay-point (once used for spaying animals) has a single, mostly straight edge that curves strongly upwards at the end to meet a short, dull, straight clip from the dull back. With the curved end of the blade being closer to perpendicular to the blade’s axis than other knives and lacking a point, making penetration unlikely, spay points can be suitable for skinning.
8. A Westernised tanto style knife has a somewhat chisel-like point that is thick towards the point (being close to the spine) and is thus quite strong. It is superficially similar to the points on most Japanese long and short swords ( katana and wakizashi ). The traditional Japanese tanto knife uses the blade geometry of (1). The Westernised tanto is often straight but may also be gently curved. The point is actually a second edge on the end of the blade, with a total edge angle of 60 – 80 degrees. Some varieties may have the back edge angled to the point slightly and sharpened for a short distance from the point.
9. A sheepsfoot knife has a straight edge and a straight dull back that curves towards the edge at the end. It gives the most control, because the dull back edge is made to be held by fingers. Sheepsfoot knives are good for whittling and trimming sheep’s hooves.
10. A Wharncliffe blade is similar in profile to a sheep’s foot but the curve of the back edge starts closer to the handle and is more gradual. Its blade is much thicker than a knife of comparable size.
11. and 12. An ulu (Inuit woman’s knife) knife is a sharpened segment of a circle. This blade type has no point, and has a handle in the middle. It is good for scraping, and sometimes chopping. It is the strongest knife shape. The semi-circular version appears elsewhere in the world and is called a head knife. It is used in leatherworking both to scrape down leather (reducing thickness), and to make precise, rolling cuts for shapes other than straight lines.
Types of Blade Edge Grinds
Now that we understand some common shapes of knives, let’s take a look at common blade edge grinds. The cutting edge is where the magic happens, but there are a variety of ways in which to actually get that edge sharp. The grind on your knife will depend on a number of factors. Cost will be one of them. Cheaper grinds like the hollow grind sacrifice edge strength and the knife’s overall longevity in order the keep the per-unit cost down. Expensive grinds like the convex grind give the blade a longer life, and leave more “meat” in the blade for re-sharpening later on, but require skill and time to resharpen.
1. Hollow ground—A common grind where a grinding wheel is used to create a convex hollow in both sides of the edge. A hollow grind blade can be very sharp, but the edge is easier to damage than other grinds due to its thinness. It isn’t well suited to cutting hard materials like wood, or chopping through bone. Straight razors are hollow ground. This grind is used extensively in mass produced knives, as it can be reproduced quickly and easily.
2. Flat ground—The blade tapers all the way from the spine to the edge from both sides. A lot of metal is removed from the blade and is thus more difficult to grind, one factor that limits its commercial use. It sacrifices edge durability in favor of more sharpness. The Finnish puukko is an example of a flat ground knife, as are most forged-blade kitchen knives. A true, flat ground knife having only a single bevel is somewhat of a rarity.
3. Sabre ground—Similar to a flat ground blade except that the bevel starts at about the middle of the blade, not the spine. It produces a more lasting edge at the expense of some cutting ability.
4. Chisel ground—As on a chisel only one side is ground (often at an edge angle of about 20 – 30°) whilst the other remains flat all the way to the spine. As many Japanese culinary knives tend to be chisel ground they are often sharper than a typical double beveled Western culinary knife. (A chisel grind has only a single edge angle. If a double bevel has the same edge angle as a chisel grind, it still has two edges and thus has twice the included angle.) Knives which are chisel ground come in left and right handed varieties, depending upon which side is ground.
5. Double bevel or compound bevel—A back bevel, similar to a sabre or flat grind, is put on the blade behind the edge bevel (the bevel which is the foremost cutting surface). This back bevel keeps the section of blade behind the edge thinner which improves cutting ability. Being less acute at the edge than a single bevel, sharpness is sacrificed for resilience: such a grind is much less prone to chipping or rolling than a single bevel blade. In practice, double bevels are common in a variety of edge angles and back bevel angles.
6. Convex ground—Rather than tapering with straight lines to the edge, the taper is curved, though in the opposite manner to a hollow grind. Such a shape keeps a lot of metal behind the edge making for a stronger edge while still allowing a good degree of sharpness. This grind can be used on axes and is sometimes called an axe grind. As the angle of the taper is constantly changing this type of grind requires some degree of skill to reproduce on a flat stone. Convex blades usually need to be made from thicker stock than other blades.
Of all the grinds, my favourite is the compound bevel. It doesn’t require unreasonable talent to reproduce. It is strong. It’s even pretty cheap. And most of all, when it comes time to reprofile a knife you can change your dull knife edge into a compound bevel to give it longevity and strength that it might have lacked as a hollow grind.
So you made it all the way to the bottom of the page. Nice work! By now, you’ve picked up a little of everything regarding what goes into a survival knife. I hope you feel more confident about the choice you’re making next time you go shopping. Remember, it doesn’t matter what the forums say – if you like the knife then it’s the best knife for you.
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