Paper cut
Encyclopedia
A paper cut occurs when a piece of paper or other thin, sharp material slices a person's skin.
Paper cuts, though named from paper, can also be caused by other thin, stiff materials, such as aluminium foil
, knives, and thin blades of grass.
Although a loose paper sheet is usually too soft to cut, it can be very thin (sometimes as thin as a razor
edge), being then able to exert high levels of pressure
, enough to cut the skin. Paper cuts are most often caused by paper sheets that are strongly fastened together (such as brand new paper out of a ream), because one single paper sheet might be dislocated from the rest. Thus all the other sheets are holding this dislocated sheet in position, and the very small part held away from the rest can be stiff enough to act as a razor.
Paper cuts can be surprisingly painful as they can stimulate a large number of skin surface pain receptors (nociceptor
s) in a very small area of the skin. Because the shallow cut does not bleed very much, the pain receptors are left open to the air, ensuring continued pain. This is exacerbated by irritation caused by the fibers in the paper itself, which may be coated in chemicals such as bleach
. Additionally, most paper cuts occur in the fingers, which have a greater concentration of sensory receptor
s than the rest of the body.
The random orientation of collagen
fibers in skin provides the ability to withstand pinpoint forces. However, skin does not have the same strength against shearing forces
and is easily cut. The same principle can be applied to performers that stand on blades.
Paper cuts, though named from paper, can also be caused by other thin, stiff materials, such as aluminium foil
Aluminium foil
Aluminium foil is aluminium prepared in thin metal leaves, with a thickness less than , thinner gauges down to are also commonly used. In the USA, foils are commonly gauged in mils. Standard household foil is typically thick and heavy duty household foil is typically .The foil is pliable, and...
, knives, and thin blades of grass.
Although a loose paper sheet is usually too soft to cut, it can be very thin (sometimes as thin as a razor
Razor
A razor is a bladed tool primarily used in the removal of unwanted body hair through the act of shaving. Kinds of razors include straight razors, disposable razors and electric razors....
edge), being then able to exert high levels of pressure
Pressure
Pressure is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.- Definition :...
, enough to cut the skin. Paper cuts are most often caused by paper sheets that are strongly fastened together (such as brand new paper out of a ream), because one single paper sheet might be dislocated from the rest. Thus all the other sheets are holding this dislocated sheet in position, and the very small part held away from the rest can be stiff enough to act as a razor.
Paper cuts can be surprisingly painful as they can stimulate a large number of skin surface pain receptors (nociceptor
Nociceptor
A nociceptor is a sensory receptor that responds to potentially damaging stimuli by sending nerve signals to the spinal cord and brain. This process, called nociception, usually causes the perception of pain.-History:...
s) in a very small area of the skin. Because the shallow cut does not bleed very much, the pain receptors are left open to the air, ensuring continued pain. This is exacerbated by irritation caused by the fibers in the paper itself, which may be coated in chemicals such as bleach
Bleach
Bleach refers to a number of chemicals that remove color, whiten, or disinfect, often via oxidation. Common chemical bleaches include household chlorine bleach , lye, oxygen bleach , and bleaching powder...
. Additionally, most paper cuts occur in the fingers, which have a greater concentration of sensory receptor
Sensory receptor
In a sensory system, a sensory receptor is a sensory nerve ending that responds to a stimulus in the internal or external environment of an organism...
s than the rest of the body.
The random orientation of collagen
Collagen
Collagen is a group of naturally occurring proteins found in animals, especially in the flesh and connective tissues of mammals. It is the main component of connective tissue, and is the most abundant protein in mammals, making up about 25% to 35% of the whole-body protein content...
fibers in skin provides the ability to withstand pinpoint forces. However, skin does not have the same strength against shearing forces
Shear stress
A shear stress, denoted \tau\, , is defined as the component of stress coplanar with a material cross section. Shear stress arises from the force vector component parallel to the cross section...
and is easily cut. The same principle can be applied to performers that stand on blades.