Ivory

See also Ivory carving.. This most likely stems from the fact that it is just not a safe thing to do. So-called hornbill ivory, derived from a bird, is not true ivory but resembles it in some ways. This is especially true in more rural areas where carrying a pocket knife is as common as carrying a set of keys. [1]. In many places in the United States it is considered bad luck to hand an open, folding blade knife to someone. It is sometimes called vegetable ivory, or tagua, and is the seed endosperm of the ivory nut palm commonly found in coastal rainforests of Ecuador and Peru. The puukko is always presented handle first as a sign of trust and friendly intentions.

A species of hard nut is gaining popularity as a replacement for ivory, although its size limits its usability. This is especially true in Finland where various non-governmental organizations, clubs and even government agencies traditionally give a puukko (a Finnish fixed-blade hunting/outdoor knife) as a gift to trusted employers or contacts. Mammoth ivory is used today to make handcrafted knives and similar implements. In some cultures giving a knife as a gift is considered a sign of respect and trust. Trade in the ivory from the tusks of dead mammoths has occurred for 300 years and continues to be legal. Stirring liquids or powders with a knife is considered unlucky; as the rhyme says, "Stir with a knife, stir up strife". Kenya, which saw its elephant populations plummet in the decade preceding the 1989 ban, claims that legalizing ivory trade anywhere in Africa will endanger elephants everywhere in Africa as poachers would attempt to launder their illegal ivory with legal stockpiles. It is common to include a penny, often taped to the blade, with a knife given as a gift which the receiver is to return as "payment".

Yet, a 1999 study done by Oxford University found that less than one percent of the five-hundred million US dollars ivory sales generate ever reach Africans; most of it goes to middlemen and vendors, so the effectiveness of the policy is in question. To avoid such ill luck, the receiver should give a coin in return so as to "pay" for the gift. In 2002 the United Nations partially lifted the ban on ivory trade, allowing a few countries to export certain amounts of ivory. In some countries it is traditionally believed that the giving of a knife as a gift to a friend will cut or sever the relationship. Many African countries including Zimbabwe and South Africa claim that ivory trade is necessary—both to stimulate their economies and reduce elephant populations which are allegedly harming the environment. Knives can be sometimes be customised to the user and/or application:. Since the worldwide ivory trade ban in 1989 there have been ups and downs in elephant populations, and ivory trade as bans have been placed and lifted. Folding knives with locking blades are not considered pen knives and are currently a legal "grey area".

Much of the decline in population is due to poachers during and before the 1980s. A special exception exists for penknives (pocket knives) which are legal without reason for possession. Due to the rapid decline in the populations of the animals that produce it, the importation and sale of ivory in many countries is banned or severely restricted. Sikhs). Additionally, warthog tusks, and teeth from sperm whales, orcas and hippos can also be scrimshawed or superficially carved, thus retaining their morphologically recognizable shapes. sgian dubh), or if it is carried for religious reasons (e.g. A small example of modern carved ivory objects are small statuary, netsukes, jewelry, flatware handles, furniture inlays, and piano keys. chefs) or if it is part of a national costume (e.g.

Tooth and tusk ivory can be carved into an almost infinite variety of shapes and objects. It is however legal to carry a knife if there is a bona fide reason to do so (e.g. The North African elephant population was probably reduced to extinction, due to the demand for ivory in the Classical world. In general, knives carried in public places are legally considered to be offensive weapons and the carrier can be charged with "possession of an offensive weapon". Ivory was often used to form the whites of the eyes of statues. In private almost any kind of knife may be owned with the exception of automatic knives (flick knives, balisongs, switchblades) which are under any circumstances illegal. Both the Greek and Roman civilizations used large quantities of ivory to make high value works of art, precious religious objects, and decorative boxes for costly objects. Knife possession is only legislated in public places.

Paleolithic Cro-Magnon man, during the late stages of the ice age, were the first to carve in ivory (mammoth tusks). include court buildings and federal property (the latter of which technically has a limit of 2.5 inch blades). The three dimensional configuration of the dentinal tubules is under genetic control and is therefore a characteristic unique to the order. Other restricted areas in the U.S. Their length is dictated by the radius of the tusk. In some metro areas such as Washington, D.C., going into office buildings or museums, or simply loitering, carrying even small 3" folding knives can be problematic. These canals have different configurations in different ivories and their diameter ranges between 0.8 and 2.2 micrometres. Cities have ordinances further restricting these laws; in San Antonio, TX, it is a violation to carry a folding knife having a locking blade.

Dentine contains a microscopic structure called dentinal tubules which are micro-canals that radiate outward through the dentine from the pulp cavity to the exterior cementum border. In some other States, fixed-blade knives are banned, open carry is banned, and sometimes concealed carry of anything except pocket knives is banned. The inorganic component of dentine consists of dahllite. 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). Dentine is a mineralized connective tissue with an organic matrix of collagenous proteins. Knife laws vary tremendously. Dentine, which is the main component of carved ivory objects, forms a layer of consistent thickness around the pulp cavity and comprises the bulk of the tooth and tusk. The knife laws of different countries vary, but are generally strict in Western countries.

Odontoblasts line the pulp cavity and are responsible for the production of dentine. Even small knives are forbidden on all commercial airliners and are among the illegal imports that may be confiscated at airports by customs staff even if packed in luggage. The pulp cavity is an empty space within the tooth that conforms to the shape of the pulp. 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. The innermost area is the pulp cavity. Most Western European nations are very unfriendly toward all knives other than small pocket knives and similarly small tools, which are nonetheless not allowed on planes or in certain other venues. Teeth and tusks have the same physical structures: pulp cavity, dentine, cementum and enamel. One exception is Austria, where civilian possession of automatic knives including double-edged automatic OTF ("out The front") daggers is allowed.

The teeth of most mammals consists of a root and the tusk proper. Balisongs (butterfly knives) are only slightly less stigmatized, and tend to be treated as switchblades by law enforcement agencies due to their connection with gang activity. Tusks, which are extremely large teeth projecting beyond the lips, have evolved from teeth and give certain species an evolutionary advantage. Automatic knives (switchblades) are almost universally banned from civilian carry if not possession. Teeth are specialized structures adapted for food mastication. chef's knives). Teeth and tusks have the same origins. Exceptions may be made for hunting knives, and for knives used for work-related purposes (e.g.

Therefore, "ivory" can correctly be used to describe any mammalian teeth or tusks of commercial interest which is large enough to be carved or scrimshawed. Carrying knives in public is forbidden by law in many countries. The chemical structure of the teeth and tusks of mammals is the same regardless of the species of origin, and the trade in certain teeth and tusks other than elephant is well established and widespread. (These thoughts were stimulated by an article posted on rec.woodworking.). . It has the same relative shape for any depth of cut. Plastics have been viewed by piano purists as an inferior ivory substitute on piano keys, although other recently developed materials more closely resemble the feel of real ivory. A wedge shape has the property called "scale invariance".

The word "ivory" was traditionally applied to the tusks of elephants. On the other hand, if the type of use cannot be predicted, it may be better to sharpen it to a wedge and let the first use bend the edge to an appropriate curve. Prior to the introduction of plastics, it was used for billiard balls, piano keys, buttons and ornamental items. Perhaps this sheds light on the function of razor straps and on the practice of using two angle guides to sharpen a knife. Ivory is a hard, white, opaque substance that is the bulk of the teeth and tusks of animals such as the elephant, hippopotamus, walrus, mammoth, etc. This contrasts to the usual practice of trying to sharpen knives to a wedge near the edge. Elk Ivory from the bugling teeth of bull elk. This is a (microscopic) parabola.

Warthog ivory. So, in this case, the ideal cross section is proportional to the square root of the distance from the edge. Hippopotamus ivory. (That explains the strength per weight of aluminum, compared to steel.) If the force is applied at the edge, the bending torque is proportional to the distance from the edge. Narwhal ivory. Both the area taking the force and the lever arm converting force to torque are proportional to thickness, so the bending resistance is proportional to the square of the thickness. Sperm Whale and Killer Whale ivory. Sheets of material are bent by stretching the outside or compressing the inside.

Walrus ivory from the tusks of a bull walrus. Assume the knife is thin and the force is applied at the very edge. Elephant and mammoth ivory from the tusks of bull elephants and mammoths. Making some simplifying assumptions about the forces and the knife edge's ability to resist them may shed some light on ideal sharpening. In this case the knife should resist bending or breaking. If a knife is used as a scraper or encounters hard particles in softer materials or is used asymmetrically, there may be a sideways load near the tip.

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. This fine process can effect alignment of the edge. Other times the final step is done with a steel. It is useful when a knife is still sharp, but has lost that 'scary sharp' edge from use.

It will not cut the edge significantly, but produces a very sharp edge with very little metal loss. 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. Stropping a knife is sometimes a finishing step. Rather expensive are sharpening blocks made with corundum.

Coated hones, which have an abrasive, sometimes diamonds, on a base of plastic or metal are another kind of hone. There are better ways than oil to clean a hone. This is generally bad to do during polishing. Oil is sometimes used to lift the metal dust, called swarf, off the stone.

Oil is not to be used on these. Generally, these are more costly than oilstones. They are stored in water, and develop a layer of slurry which dulls the edge if you hone the blade as if honing into the stone. Water stones (both artificial and natural) come in very fine grits.

Ceramic hones are also common, especially for fine grit size. India is another traditional source for stones. Arkansas is a traditional source for honing stones, which are traditionally (though a poor practice) used with water or honing oil. Honing stones (also called whetstones) come with coarse and fine grits and can be hard or soft describing whether the grit comes free.

If you feel a little bit of pull at the edge or the nail is sightly abraded, you may have a wire burr. It should come off with no resistance. To feel for a wire edge, move your thumb lightly across the edge. This will flip the burr back and forth as it is ground off.

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

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

The composition of the stone affects the sharpness of the blade (finer grain produces sharper blades), as does the composition of the blade (some metals take/keep an edge better than others). In general, the harder the material to be cut the higher the angle of the edge. For an extremely durable edge (such as a chisel or drawknife), sharpen to 30 degrees. Knives that require a tough edge (such as those that chop) sharpen at 20 degrees.

Typical knives sharpen at 15 degrees. Very sharp knives sharpen at 10 degrees. A guide is very helpful. The smaller the angle between the blade and stone, the sharper the knife will be, but the faster it will dull.

Knives are sharpened by grinding against a hard surface, typically stone. However, this may also make them brittle. Most high-quality knives are also tempered very hard, so that they will retain an edge longer. Either use is likely to break off the tip of the blade, or to bend or break the knife beyond repair.

Most knives are not intended as pry bars or screwdrivers. Steel blades rust easily, but oiling will prevent pitting due to oxidation and tarnish. A knife should be kept clean, dry and sharp. Conversely it can be argued that what is dangerous is not knowing how sharp a knife is and thus how much force to use.

Also, a dull or damaged knife will inflict a worse wound than a relatively 'clean' cut from a sharp knife. Dull knives lead to excessive use of force to cut materials, increasing the chance that the blade may slip and the force will be transferred to an unintended destination such as the user or another person or object. A sharp knife is often claimed to be a safer knife. Knives offered to another person should always be offered handle first.

When checking the blood circle it is best to hold the knife by the blade, otherwise you defeat the purpose. In Boy Scout parlance, an area within the radius of the arm and blade length combined is called the "blood circle". By extension, assume that the knife is going to slip, and look where the blade would go. "Always cut away from yourself" is the basic adage to keep in mind while using a knife.

Chopping knives need blunter angles, out to thirty degrees. Slicing knives should have sharper angles, down to ten degrees. 15 to 25 degrees is a good all-around angle. The edge is sharpened at different angles for different purposes.

A good serration pattern will stay sharp several times as long as a straight edge. The points protect the slicing areas from nicks. Serrations on a blade "saw" through the item being cut and stay sharp for a long time. For whittling (artistic wood carving) a blade as short as 25mm (1 inch) is common.

Many knives are specific to a particular activity or occupation:. Some knives, such as the Scottish dirk and Japanese Tanto function in both roles. In general, knives are either working knives (everyday-use blades), or fighting knives. Knives exist in several styles:.

Knives can be categorized based on either form or function. It handles much like the clip-point. A drop-point blade is very similar to a clip point, but it features the back convexed down, rather than having a clip taken out of it. An example is a head knife, used in leatherworking both to scrape down leather (reducing thickness), and to make precise, rolling cuts to form shapes.

It is the strongest knife-shape. It's good for scraping, and sometimes chopping. This sort of blade is all edge, with no point, and a handle in the middle. An ulu (Inuit woman's knife) knife is a sharpened half-circle.

The point is actually a second edge on the end of the blade, with a total edge angle of 60-80 degrees. The edge is straight. The traditional Japanese tanto knife uses the blade geometry of (1). It is superficially similar to the points on most Japanese long and short swords (katana and wakizashi).

(6) An Americanized tanto style knife is thick towards the point. Sheepsfoot knives are good for whittling, including sheep's hooves. It gives the most control, because the dull back edge is made to be held by fingers. (5) A sheepsfoot knife has a straight edge, and a curved dull back.

The Bowie has a clipped blade. If the false edge is sharpened it increases the knife's effectiveness in piercing. The sharp tip makes the blade exceptional as a pick, or for cutting in tight places. The back edge of the clip can have a false edge that can be sharpened to make a second edge.

(4) A clip point blade is like a normal blade with the tip "clipped" to make the tip thinner and sharper. This shape is primarily used for fighting knives (daggers, bayonets) because it can cut in both directions and point in line with the handle. The idea is to make a blade that cuts in either direction, with a strong sharp point. (3) A double edged or spey blade has two edges.

Such a knife is better for slicing than a normal knife. This lets a lightweight knife have a larger curve on its edge. (2) A curved, trailing-point knife has a back edge that curves upward. Therefore, the knife can chop as well as pick and slice.

The curve concentrates force on a small point, making cutting easier. A dull back lets the wielder use fingers to concentrate force; it also makes the knife heavier and stronger for its size. (1) A normal blade has a curving edge, and flat back. There are a variety of knife blade shapes; some of the most common are listed below.

Vanadium, and perhaps molybdenum, also increase corrosion resistance. Vanadium and molybdenum are important alloy metals because they make the gain size smaller, which improves hardness and toughness. These explain its reputation for long wear (the carbides are harder than the metal) and for being harder to sharpen and not taking as good an edge as rustable, low alloy ("carbon") steel (the ceramic particles themselves cannot be sharpened easily.) The bulk hardness and toughness of stainless steel tend to be lower than those of low alloy steel. Stainless steel usually has particles of chromium (or other alloy metal) carbides.

It is corrosion resistant (though knife steel is less so than higher nickel stainless steel) because, except in acid, one of the metals or one of the oxides is always stable. Stainless steel is steel with very high (12–18%) chromium content. Stainless knife steels are high in carbon, but "carbon steel" means there is not also a lot of chromium. Knife steel has fairly low nickel content, because nickel tends to keep steel in the austenitic structure, even when cold.

The blade is then tempered by heating to an intermediate temperature for a period to make it less brittle. It is formed as it is quenched, changing it from the austenitic structure that it has at high temperature to a hard, but brittle martensitic structure. All knife steel is tempered martensite, which means that a fine-grained crystal structure with lattice irregularities that make it hard. Some manufacturers, particularly of kitchen knives, make ceramic blades; these are harder and stay sharp longer, but because of their brittleness, chip and break more readily.

Forschner/Victorinox make decent, inexpensive kitchen knives; high-end manufacturers include Wüsthof, Global, Henckels and Böker (Tree Brand). There is typically more demand for exotic alloys in the utility, outdoor, and tactical or combat knife categories than there is in the kitchen knife category. The cost of the process restricts it to high-end knives. The original craft of Damascus steel may be lost, but not being a registered trademark, the name is today used to apply to the equally old but less exotic pattern welding, which creates layered and admired patterns.

All three are more ductile than typical stainless steels, but have quite a vocal support group despite concerns about health effects of cobalt content. Other manufacturers sometimes use titanium, cobalt, and cobalt containing alloys. Knife manufacturers such as Spyderco and Benchmade typically use 154CM, VG-10, S30V, and CPM440V (also known as S60V), as well as high-speed high-hardness tool steels like D2 and M2. A variety of exotic steels and other materials can be used to form blades.

Steels having high carbon but low chromium content are prone to rust and pitting if not kept dry. Chromium is the major alloying element in stainless steels, giving them the 'stainless' quality. Stainless and semi-stainless steels include D2, S30V, 154CM, ATS-34, and 440C. Tests done by Razor Edge Systems, and described in their book "The Razor Edge Book of Sharpening" indicate that stainless steel knives hold an edge better than regular steels.

Stainless steels have gained popularity in the latter half of the twentieth century because they are highly resistant to corrosion (so they usually only rust under extreme conditions). Knife blades are usually made of steel; although there are a few knives using materials like high tech ceramic and titanium, these are very uncommon. A hole in the end of the handles allows the knife to be hung or placed on a lanyard. For a large knife, it is desirable that the handle is thick enough that one's fingers just meet one's palm when the knife is gripped tightly.

The handle of a knife should be made of a non-slip material. In kitchen knives, it keeps chopped items from moving back toward the hand. In piercing, this helps keep the knife from jamming, for example in bone. See 1 Some knives also have a shoulder in which the blade thickens as it meets the handle.

Additionally, a groove on the blade can reduce surface tension between the blade and the item being cut, thereby allowing easier movement or removal of the blade. In reality, its only function is to make knives and swords lighter while sacrificing little strength; on most knives it has more decorative worth. According to a popular myth, it lets bleeding occur from an artery without removing the knife. A fuller, sometimes called a blood gutter or blood groove, is a groove on the side, along a blade.

The blade in turn consists of a tip, a spine, an edge and a heel. The bolster functions as a balance point and handguard, to prevent fingers from slipping onto the blade. The tang is an extension of the blade into the handle. A knife consists of a tang, a bolster, a blade and a handle.

. The importance of the knife as a weapon has declined as more specialized weapons have been developed, but the knife remains the universal tool. In the West, multi-purpose pocket knives are commonly carried, to be available anywhere. Today, these are not frequently sharpened, and most sharp knives are used in kitchens.

Together with the fork and spoon, the knife has been a common eating utensil in the Western world since, at least, the Middle Ages. While the materials have changed over time, the basic design remains the same. Later on with advances in smelting and metallurgy the blades were made of bronze, iron, then steel. The first knives were flint or other rock, chipped or ground to an edge, sometimes with a handle.

Knives have been used as tools and weapons since the Stone Age. The blade of a knife is usually pointed and may have one or two cutting edges. A knife usually consists of a blade, commonly less than 12 inches (30cm) in length, attached to a handle. A knife is a sharp-edged hand tool used for cutting.

Everybody's Knife Bible by Don Paul, ISBN 0938263234. The surface finish of the blade can be darkened or polished. The handle can be altered in shape (for better grip) or material (to prevent electric shock or burns).