A knife is a sharp-edged hand tool used for cutting. A knife usually
consists of a blade, usually less than 12 inches (30cm) in length,
attached to a handle. The blade of a knife is usually pointed
and may have one or two cutting edges. Knives have been used as
weapons and tools since the Stone Age.
knives were flint or other rock, chipped or ground to an edge,
sometimes with a handle. Later on with advances in smelting and
metallurgy the blades were made of bronze, iron, then steel. While
the materials have changed over time, the basic design remains
A knife consists
of a blade, a tang and a handle. The tang is an extension of the
blade into the handle. Some knives have a handguard, so that fingers
cannot slip onto the edge and be cut.
A blood groove
or fuller is a 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 and, for its weight, stronger; on most knives
its function is purely decorative.
also have a shoulder in which the blade thickens as it meets the
handle. This helps keep the knife from jamming in bone. In kitchen
knives, it keeps chopped items from moving back toward the hand.
of a large knife should be made of a non-slip material, such as
Kraton, and should be thick enough that one's fingers just meet
one's palm when the knife is gripped as tightly as possible. A
hole in the end of the handles allows the knife to be hung or
placed on a lanyard.
usually made of steel(s), though there are a few knives using
materials like high tech ceramic and titanium, but these are very
uncommon. Stainless steels have gained popularity in the latter
half of the twentieth century because they are highly resistant
to corrosion (though they can rust under extreme conditions).
There is a trade-off between edge-holding and resistance to corrosion,
but newer semi-stainless steels like D2 may offer the best compromise.
Modern stainless steels include S30V, 154CM, ATS-34, and 440C.
Chromium is the major alloying element in stainless steels, it
causes them to be 'stainless'.
steels, as their name implies are a high carbon, low chromium
alloy, and are very prone to rust and pitting if not kept dry.
They are generally used for their excellent 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.
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.
Forschner/Victorinox make decent cheap kitchen 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.
are a variety of knife blade shapes; some of the most common are
A normal (1)
blade has a curving edge, and flat back. A dull back lets the
wielder use fingers to concentrate force; it also makes the knife
heavier and stronger for its size. The curve concentrates force
on a small point, making cutting easier. Therefore, the knife
can chop as well as pick and slice.
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 Double edged
or spey (3) blade has two edges. The idea is to make a blade that
cuts in either direction, with a strong sharp point. This shape
is primarily used for fighting knives (daggers, bayonets) because
it can cut in both directions, has a sharp point, and is strong.
A clip point
(4) blade is like a normal blade with the tip "clipped"
to make the tip thinner and sharper. The back edge of the clip
can have a false edge that can be sharpened to make a second edge.
The sharp tip makes the blade exceptional as a pick, or for cutting
in tight places. If the false edge is sharpened it increases the
knife's effectiveness in fighting. The Bowie has a clipped blade
that is strong and good for fighting.
(5) knife has a straight edge, and a curved dull back. It gives
the most control, because the dull back edge is made to be held
by fingers. Sheepsfoot knives are good for whittling, including
A tanto style
(6) knife is thick. It is superficially similar to the points
on most Japanese long and short swords (katana and wakizashi),
although is a bit of a misnomer as the traditional Japanese tanto
(dagger) does not share this point style. 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. This sort of blade is 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. An example
is a head knife, used in leatherworking both to scrape down leather
(reducing thickness), and to make precise, rolling cuts to form
blade is very similar to a clip point, but it features the back
convexed down, rather than having a clip taken out of it. It handles
much like the clip-point.