Knife

A knife is a sharp object used for cutting things. The most common design for a knife is that of a sharp metal blade attached to a handle by means of a tang. Knives have been used as weapons and tools since the stone age, and various developments include the sword and the machete.

As a verb, to knife is to use a knife to injure or kill by stabbing, slashing, or other use of the sharp edge of the knife as a weapon.

traditional Norse knife (photo )

Together with the fork and spoon it is a very common eating utensil. According to etiquette it is held in the right hand, and the fork in the left.

A knife is such a basic tool that it is helpful in almost any environment.

Knives were among the first tools used by man in the Stone age, originally consisting of a single piece of sharpened flint.

Table of contents

1 Using knives 2 Sharpening 3 Knives to carry 4 Anatomy of a Knife 4.1 Folding Knives 5 Blades 6 Types of knives 6.2 Knife modifications 7 See also 8 Further reading

Using knives

A sharp knife is a safe knife. Dull knives lead to excessive use of force to cut materials, increasing the chance that the blade may slip and that the force will be transferred into your finger or hand. Neither destination is desirable.

Keep the knife clean, dry and sharp. If the blade can rust, oiling it will prevent pitting, tarnish, and rust.

Most knives are not intended as pry bars or screwdrivers. Either use is likely to break off the tip of the blade, or to bend or break the knife horribly. Most high quality knives are also tempered very hard, so that they will retain an edge longer. However, this also makes them brittle, and prying with them is undesirable.

In the woods, use the knife as a tool to make tools, rather than as the only tool. For example, rather than using it as a skewer, use it to cut skewers from a nontoxic wood.

To cut thick wood, chopping with a knife is almost always faster than using a saw on the back of the knife, but if you have no means of resharpening the blade chopping with a knife is a good way to make it useless.

Sharpening

The trick is to control the angle between the stone and knife. It should be constant. A tool is very helpful. Very sharp knives sharpen at 12 degrees. Typical knives sharpen at 22 degrees. Knives that chop may sharpen at 25 degrees. In short, the harder the material to be cut the larger the angle of the edge.

Examples of sharpening tools are the clamp-style systems, which use a clamp with several holes with pre-defined angles. The stone is mounted on a rod and is pulled through these holes, so that the angle remains consistent. Another variant is the crock stick setup, where two sticks are put into a plastic or wooden base to form a V shape. When you pull a knife up the V, the angle is held for you, as long as you hold the blade perpendicular to the base.

Remove a wire edge (burr) if one forms during sharpening. Use a slighly steeper ange with very light pressure to do so. If not removed, it will break off in use, and the knife will instantly become dull. An alternate method of removing a wire edge is stroking it as one would from side to side on a very fine stone, using light strokes. This will flip the burr back and forth as it is ground off.

To feel for a wire edge, drag your thumb or thumbnail from spine to edge. It should come off with no resistance. If you feel a little bit of pull at the edge, you may have a wire burr.

Traditional stones are arkansas stones, which come in soft (coarse) and hard (fine) varieties. These are traditionally used with honing oil, but any oil compound, including olive oil, will do. India stones are also similar to arkansas stones in function and end result.

Ceramic stones are also use very often. Unlike natural stones, they will not wear, and are very often used without any type of oil.

Water stones (both artificial and natural) come in very fine grits. They are stored in water, and develop a layer of slurry which helps polish off the edge. Generally, these are more costly than oilstones. Needless to say, oil should not be used on these.

Oil is used to lift the metal dust, called swarf, off the stone. This is usually recommended for natural stones, but some say that detergent and a brillo pad will have the same effect. Ceramic stones do not need oil, they can be cleaned off with detergent. Diamond stones should NOT be used with oil, rather, they can be washed off with water.

The best sharpening stones are industrial diamonds embedded in plastic or metal. These are more expensive, but still affordable. They cut about twice as fast as other stones.

Stropping a knife is an excellent finishing step. This is traditionally done with a leather strap impregnated with abrasive compounds, but can be done on paper, cardstock, or even cloth in a pinch. It will not cut the edge significantly, but produces a very sharp edge with very little metal loss. It is useful when a knife is still sharp, but has lost that 'scary sharp' edge from use.

Steeling isn't actually sharpening nor honing. All you are doing with a sharpening steel is realigning the edge. Realigning the edge goes a long way in keeping the knife sharp, as often times, a rolled edge will make an otherwise sharp knife dull. There is no reason to remove excess metal if the edge can be fixed with several strokes on a sharpening steel.

Knives to carry

Many authorities recommend carrying a lockback knife, about 4" (10cm) long. It should be one which can be opened with one hand. The main use is a tool, not a weapon.

One authority recommends, for wilderness use, carrying a large knife like a machete or kukri, for chopping wood, serious fighting and heavy camp chores, a 6" knife for dressing animals and use as a spear-head, and to back-up the fighting knife, a lock-back folder for light tasks, and Swiss Army knife for all the little tools.

Most people carry folding knives in a pocket or clipped to their waistband, and carry a fixed-blade knives in a sheath inside their waistband or in a visible belt sheath, both of which typically rely on a belt for support. Most sheaths for fixed knives are made of kydex, a hard plastic material. Other materials, more often used for folding knife belt holsters, include ballistic nylon and leather.

Knives are forbidden on commercial airlines and are among the illegal imports that may be confiscated at airports by customs staff even if packed in luggage. Other restricted areas in the U.S. include court buildings and federal property (the latter of which technically has a limit of 2" for blades).

Knife laws in U.S. cities vary tremendously. In Texas, for example, individuals may carry knives openly or concealed so long as they are single-edged, and are not daggers, switchblades, or gravity knives (balisong legality is questionable... there have been convictions). In some other States, fixed-blade knives are banned, open carry is banned, and sometimes concealed carry of anything except pocketknives is banned. Cities have ordinances further restricting these laws; in San Antonio, TX, it is a violation to carry a folding knife having a locking blade. In some metro areas such as D.C., going into office buildings or museums, or simply loitering, carrying even small 3" folding knives can be problematic.

Knife laws outside the U.S. vary also, but are generally strict. Carrying of knives in public is forbidden by law in many countries. Exceptions may be made for hunting knives, and for knives used for work-related purposes (e.g. chef's knives). Automatic knives (switchblades) are almost universally banned from civilian carry if not possession. Balisongs (butterfly knives) are only slightly less stigmatized, and tend to be treated as switchblades by unfriendly law enforcement agencies. Most Western European nations are very unfriendly toward all knives other than SAKs (Swiss Army Knives, by Victorinox or Wenger) or similarly small tools, which are nonetheless not allowed on planes or in certain other venues. Even multitools like the SwissTool, Gerber multitools, and Leatherman multitools are often frowned upon, due to their having relatively large blades and/or locking ability.

Anatomy of a Knife

A knife has a blade, a tang and a handle. The tang is an extension of the blade into the handle, so that the handle can be strongly attached to the blade.

Some knives have quillions between the blade and the handle, so that fingers cannot slip onto the edge and be cut. Quillions should be rounded so that they do not cut fingers, and strong enough so that they do not bend before the knife breaks. A nice feature is to curve the top quillion so a thumb can be placed on it.

Some knives have a choil, a crack, finger-hole or other space between the edge and the handle. A functional choil is a circular cut-out between the blade and the handle. It's often knurled. A functional choil lets the user grip a knife with the bottom quillion between the index and middle finger. This lets one use the index finger to feel where the edge is cutting. For less-delicate cuts, the index finger is kept safe behind the quillion. Some pocket knives have only a choil, and no quillion, so they can slip easily into a pocket.

A blood groove is a large groove up the side of a blade. According to a popular myth, it lets bleeding occur from an artery without removing the knife. In reality, its only function is to make larger knives and swords lighter; on smaller knives it's purely decorative.

Some knives also have a shoulder in which the blade thickens as it meets the handle. This helped keep the knife from jamming in bone. In kitchen knives, it keeps chopped items from moving back toward the hand.

The handle should be thick enough that one's fingers just meet one's palm when the knife is gripped as tightly as possible. Most knife handles are much too thin, and a knife for serious use may need to have its handle built up with cord and tape. A favorite handle material is a sticky non-slip rubber material called Kraton.

Blades

Blades are either stainless or high-carbon, and there's an inevitable trade-off between performance and resistance to stains and rust. Modern stainless steels include S30V, 154CM, ATS-34, 440C, though even they can be made to rust. Chromium is the major alloying element in stainless steels, it causes them to be 'stainless'.

A more stainless steel is H-1, which is low in carbon while high in Manganese, Nickel, and Sulphur, and contains Nitrogen as well. H-1 is almost impossible to rust in all but the most corrosive envronments. Carbon steels are as their name implies high in carbon, low chromium, are more prone to rust and pitting, and are generally developed with the goal of good edge-holding ability.

As of 2004 there are a variety of exotic steels and other materials used to form blades. Knife manufacturers such as Spyderco and Benchmade typically use 154CM, VG-10, S30V, and CPM440V, as well as several high-speed high-hardness tool steels like D2 and M2. Other manufacturers sometimes use titanium, stellite, talonite, and other cobalt-containing alloys. All three are more ductile than typical stainless steels, but have quite a vocal support group despite concerns about health effects of the latter two alloys' cobalt content. Damascus steel, which is layered and instantly recognizable by its beautiful patterns, is typically used in high-end knife blades and has respectable edge retention. There is typically more demand for stainless steels and exotic alloys in the utility, outdoor, and tactical knife categories than there is in the kitchen knife category.

Kitchen knife blades tend to fall into two categories. Some use stainless steels to prevent users from having to pamper their blades and to be more forgiving on those who put chefs' knives in the dishwasher. Others are high in carbon for edge-holding ability, the presumption being that kitchens are not the wilderness and that chefs are willing to clean knives properly in exchange for better edge retention in economy steels. Forschner/Victorinox makes decent cheap chefs' knives; higher-end manufacturers include Wustoff, Global, and Henckels. Some manufacturers, particularly of kitchen knives, make ceramic blades; these stay sharp longer but due to their hardness chip more readily, and an accidental drop may chip, crack, or shatter the blade.

There are several basically different types of knife blades: normal, spey, clipped, sheeps-foot, tanto and ulu.

A normal (1) blade has a curving edge, and flat back. A dull back lets one use fingers to concentrate force, and makes the knife heavier and stronger for its size. The curve concentrates force, making cutting easier. Therefore, it can chop as well as pick and slice. The single edge is also less expensive to produce than a double edge.

A curved or trailing-point (2) knife has a back edge that curves upward. This lets a lightweight knife have a larger curve on its edge. Such a knife is better for slicing than a normal knife.

A spey (3) blade has two curved edges. The idea is to make a blade that slices in either direction, with a strong sharp point. This is the strongest traditional style of knife. It's used for fighting knives (dagger, switchblades, etc.) because it can cut both directions, has a point and is strong. Many persons believe that the best all-around blade is an asymmetric spey, with the larger curve on the lower side. This is called a dropped spey.

A clipped (4) blade is like a normal blade with a clip off the tip to make the tip thinner and sharper. The back edge of the clip can have a "cut swedge" that can be sharpened to make second edge. The sharp tip makes the blade exceptional as a pick, or for cutting in tight places. If the clip is sharpened, this is an attempt to make a working knife double as a fighting knife. This is another favorite knife shape, although it is not as strong as a spey. The Bowie is an attempt to make a clipped blade that's good for fighting, and as strong as a spey.

A sheepsfoot (5) knife has a straight edge, and a curved dull back. It give the most control, because the back, dull edge is made to be held by fingers. It's good for whittling, including sheep's hooves.

Clip Point blade

A tanto (6) knife is thick, almost a bar. The edge is straight. The point is actually a second edge on the end of the blade, swept back from the point at 80-60 degrees.

An ulu knife is a sharpened half-circle. It's all edge, with no point, and a handle in the middle. It's good for scraping, and sometimes chopping. It is the strongest knife-shape.

A drop-point blade is very similar to a clip point, but it features the black convexed down, rather than having a clip taken out of it. It's handing characteristics and overall form is very similar to the clip-point.

Drop-Point Blade

Types of knives

Solid tang knives are the strongest and simplest type.

A lockback knife is a folding knife with a lock. One should be able to open it with one hand, using a stud or fingerhole to get leverage. If one must carry just one knife, many authorities agree that this is the one.

A hunting knife is normally used to dress large game. It is often a normal, mild curve or a curved and clipped blade.

A stockman's knife is a very versatile folding knife with three blades: a clip, a spey and a normal. It is one of the most popular folding knives ever made.

A pocket knife is a folding knife, without locks. Some brands, such as Victorinox, have a wide variety or tools available.

A classic lady's knife is a small curved knife that folds into a handle and then resembles a silver leaf.

Pure fighting knives are always speys, so that either edge can cut. Modern fighting knives have large curves, to concentrate the force to permit slicing. Classic fighting knives have straight edges and a very strong point.

A machete is a large normal blade, used to chop through brush. Interestingly, some experts are now arguing that a long, very sharp blade is superior to a traditional heavy machete for cutting brush.

Machete

A kukri is a fighting knife with a deep forward curve. In use, it swings into a person. The kukri is also good for chopping. Some shapes actually chop better than a hatchet, because they balance better.

A survival knife is a sturdy knife, sometimes with a hollow handle filled with equipment. In the best hollow-handled knives, both blade and handle are cut from a single piece of steel. The end has an O-ring seal to keep water out of the handle. Often a small compass is set in the inside, protected part of the pommel/cap. The pommel may be adapted to pounding or chipping. Recommended fillings for the handle: a compass (usually in the pommel). Monofilament (for snares, fishing), 12 feet of black nylon thread and two needles, a couple of plastic ties, two barbed and one unbarbed fishhook (unbarbed doubles as a suture needle), butterfly bandages, halizone tablets, waterproof matches.

Knife modifications

Most knives need a fatter handle to fit most people's hands. The handle should get a hole, if it doesn't have one. The handle can have a couple notches to make it easier-to use plastic ties to mount it on a spear.

The tang should be covered on the handle, so that it cannot burn, freeze or shock the knife's user.

The pommel might be modified to be sturdy enough to pound or chip. One can drive a large machine screw in. The sheath should permit one to hold the blade for pounding and chipping.

One side of the blood groove or blade could be polished to make a signal mirror. If this is done, drill a small hole to act as the aiming hole. One aims a signal mirror by looking through the hole, and moving the reflection of the beam through the hole over the target seen through the hole.

A knife with simple surveying instruments is more useful. One standard system puts a sighting hole in the upper quillion to aim over the point. A weighted string draped on a notch is the indicator. A sundial and half-circle degree protractor is marked on the right side of the knife. In the afternoon, sighting the sun, the sundial should show the hours to darkness. On the left side, put two trig scales. Sighting up gives a sine scale, in percent of the distance, to measure height. Sighting down gives a tangent scale, in percent of the distance, to measure the observer's height. A main use of these is for navigation. Another is to estimate rope use, and climbing effort.

Knives designed for specific purposes exist in large numbers. Some examples include butchering, hunting, curing, fishing, woodcarving, cooking and combat.

See also

• Box-cutter knife.

"Knives" is also an episode of the science-fiction television series Babylon 5; see Knives (Babylon 5).