A Pair of Scissors Consists of Two Pivoted Blades

A pair of scissors consists of two pivoted blades. In lower quality scissors the cutting edges are not particularly sharp; it is primarily the shearing action between the two blades that cuts the material. In high quality scissors the blades can be both extremely sharp, and tension sprung - to increase the cutting and shearing tension only at the exact point where the blades meet. The hand movement (pushing with the thumb, pulling with the fingers in right handed use) can add to this tension. An ideal example is in high quality tailors scissors or shears, which need to be able perfectly cut (and not simply tear apart) delicate cloths such as chiffon and silk. Children's scissors are usually not particularly sharp, and the tips of the blades are often blunted or 'rounded' for safety. Mechanically, scissors are a first-class double-lever with the pivot acting as the fulcrum. For cutting thick or heavy material, the mechanical advantage of a lever can be exploited by placing the material to be cut as close to the fulcrum as possible. For example, if the applied force (at the handles) is twice as far away from the fulcrum as the cutting location (i.e., the point of contact between the blades), the force at the cutting location is twice that of the applied force at the handles. Scissors cut material by applying a local shear stress at the cutting location which exceeds the material's shear strength. For people who do not have the use of their hands, there are specially designed foot operated scissors. Some quadriplegics can use a motorized mouth-operated style of scissor. Kitchen scissors Kitchen scissors, also known as kitchen shears, are traditionally used in the kitchen for food preparation, although due to their tough nature they can serve many other purposes. In modern times they are often made from stainless steel (for food hygiene and oxidization-resistance reasons). They often have kitchen functionality (other than cutting) incorporated, such as bottle-cap and bottle-openers built into the handles. Handed scissors Most scissors are best-suited for use with the right hand, but left-handed scissors are designed for use with the left hand. Because scissors have overlapping blades, they are not symmetric. This asymmetry is true regardless of the orientation and shape of the handles: the blade that is on top always forms the same diagonal regardless of orientation. Human hands are also asymmetric, and when closing, the thumb and fingers do not close vertically, but have a lateral component to the motion. Specifically, the thumb pushes out and fingers pull inwards. For right-handed scissors held in the right hand, the thumb blade is further from the user's body, so that the natural tendency of the right hand is to force the cutting blades together. Conversely, if right-handed scissors are held in the left hand, the natural tendency of the left hand would be to force the cutting blades laterally apart. Furthermore, with right-handed scissors held by the right-hand, the shearing edge is visible, but when used with the left hand, the cutting edge of the scissors is behind the top blade, and one cannot see what is being cut. Some scissors are marketed as ambidextrous. These have symmetric handles so there is no distinction between the thumb and finger handles, and have very strong pivots so that the blades simply rotate and do not have any lateral give. However, most "ambidextrous" scissors are in fact still right-handed in that the upper blade is on the right, and hence is on the outside when held in the right hand. Even if they successfully cut, the blade orientation will block the view of the cutting line for a left-handed person. True ambidextrous scissors are possible if the blades are double-edged and one handle is swung all the way around (to almost 360 degrees) so that the back of the blades become the new cutting edges. Patents (U.S. Patent 3,978,584) have been awarded for true ambidextrous scissors. Specialized scissors Among specialized scissors and shears used for different purposes are: Agriculture and animal husbandry Grass and hedge shears are used for trimming grass and hedges. Pruning shears (secateurs) and loppers are gardening scissors for cutting through branches of trees and shrubs. Sheep shears and machine shears are used for cutting an animal's fleece to make wool. General domestic use Kitchen scissors are for general-purpose kitchen use Nail scissors, for cutting finger- and toenails Poultry shears are used to cut cooked poultry. Specialized scissors with concave blade edges have been designed for use as a cigar cutter. Hair care Thinning scissors are used for thinning thick hair to avoid a bushy look Hair clippers – for cutting hair by barbers, hairdressers, and pet groomers. Functionally like several small pairs of scissors side-by-side, operated by a single handle or a motor. Metalwork Jaws of Life are hydraulic rescue tools for cutting heavy sheet metal. Throatless shears are used for cutting complex shapes in sheet metal. Tin snips are scissors for cutting through sheet metal. Trauma shears, or "tuff cuts", are robust scissors used in emergency medical response and rescue. Sewing and clothes-making Pinking shears are scissors with a serrated cutting edge for cutting cloth so that the fabric does not fray. Sewing Chatelaine Scissors. Chatelaine is a French term meaning "mistress of a castle, chateau or stately home", and dates back to the Middle Ages. It refers to an ornamental clasp or hook from which chains were hung from the waist, holding perhaps, a purse, watch, keys, scissors or thimble case. The sewing chatelaine became a popular ornamental appendage worn by Victorian ladies at their waist, but disappeared when fashion changed and skirts were no longer full and long. Sewing chatelaines are now produced and worn as pendants around the neck. Ceremonial Ceremonial Scissors are scissors used, and often presented for, ceremonial ribbon-cutting events such as building openings etc. Source: en.wikipedia.org