Squib (explosive)
Encyclopedia
Special effect
The illusions used in the film, television, theatre, or entertainment industries to simulate the imagined events in a story are traditionally called special effects ....
s to military
Military
A military is an organization authorized by its greater society to use lethal force, usually including use of weapons, in defending its country by combating actual or perceived threats. The military may have additional functions of use to its greater society, such as advancing a political agenda e.g...
applications. It resembles a tiny stick of dynamite
Dynamite
Dynamite is an explosive material based on nitroglycerin, initially using diatomaceous earth , or another absorbent substance such as powdered shells, clay, sawdust, or wood pulp. Dynamites using organic materials such as sawdust are less stable and such use has been generally discontinued...
, both in appearance and construction, although with considerably less explosive power. Squibs consists of two electrical leads which are separated by a plug of insulating material, a small bridge wire or electrical resistance heater, and a bead of heat-sensitive chemical composition in which the bridge wire is embedded. Squibs can be used for generating mechanical force
Force
In physics, a force is any influence that causes an object to undergo a change in speed, a change in direction, or a change in shape. In other words, a force is that which can cause an object with mass to change its velocity , i.e., to accelerate, or which can cause a flexible object to deform...
, or to provide pyrotechnic effects for both film
Film
A film, also called a movie or motion picture, is a series of still or moving images. It is produced by recording photographic images with cameras, or by creating images using animation techniques or visual effects...
and live theatrics. Squibs can be used for shattering or propelling a variety of materials.
A squib generally consists of a small tube filled with an explosive substance, with a detonator
Detonator
A detonator is a device used to trigger an explosive device. Detonators can be chemically, mechanically, or electrically initiated, the latter two being the most common....
running through the length of its core, similar to a stick of dynamite. Also similar to dynamite, the detonator can be a slow-burning fuse
Fuse (explosives)
In an explosive, pyrotechnic device or military munition, a fuse is the part of the device that initiates function. In common usage, the word fuse is used indiscriminately...
, or as is more common today, a wire
Wire
A wire is a single, usually cylindrical, flexible strand or rod of metal. Wires are used to bear mechanical loads and to carry electricity and telecommunications signals. Wire is commonly formed by drawing the metal through a hole in a die or draw plate. Standard sizes are determined by various...
connected to a remote electronic
Electronics
Electronics is the branch of science, engineering and technology that deals with electrical circuits involving active electrical components such as vacuum tubes, transistors, diodes and integrated circuits, and associated passive interconnection technologies...
trigger
Trigger
-Technology:* Trigger , a mechanism that actuates the firing of firearms* Image trigger, a device used in highspeed cameras* Schmitt trigger, an electronic circuit* Trigger circuit, IBM's name for a flip-flop...
. Squibs range in size, anywhere from 2 to 15 millimeters in diameter.
In the North American
North American
North American generally refers to an entity, people, group, or attribute of North America, especially of the United States and Canada together.-Culture:*North American English, a collective term used to describe American English and Canadian English...
film industry, the term squib is often used to refer variously to: electric match
Electric match
An electric match is a device that uses an externally applied electric current to ignite a combustible compound.-Use:Electric matches can be used in any application where source of heat is needed at a precisely controlled point in time, typically to ignite a propellant or explosive...
es and detonator
Detonator
A detonator is a device used to trigger an explosive device. Detonators can be chemically, mechanically, or electrically initiated, the latter two being the most common....
s (used as initiators to trigger larger pyrotechnics). Squibs are generally (but not always) the main explosive element in an effect, and as such are regularly used as “bullet hits”.
Uses
Squibs were once used in coal miningCoal mining
The goal of coal mining is to obtain coal from the ground. Coal is valued for its energy content, and since the 1880s has been widely used to generate electricity. Steel and cement industries use coal as a fuel for extraction of iron from iron ore and for cement production. In the United States,...
to break coal away from rock
Rock (geology)
In geology, rock or stone is a naturally occurring solid aggregate of minerals and/or mineraloids.The Earth's outer solid layer, the lithosphere, is made of rock. In general rocks are of three types, namely, igneous, sedimentary, and metamorphic...
. In the 1870s, some versions of the device were patented and mass-produced as "Miners' Safety Squibs".
Today, squibs are widely used in the motion picture special effect
Special effect
The illusions used in the film, television, theatre, or entertainment industries to simulate the imagined events in a story are traditionally called special effects ....
s industry to simulate bullet
Bullet
A bullet is a projectile propelled by a firearm, sling, or air gun. Bullets do not normally contain explosives, but damage the intended target by impact and penetration...
impacts on inanimate objects. Items such as sand
Sand
Sand is a naturally occurring granular material composed of finely divided rock and mineral particles.The composition of sand is highly variable, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal...
, soil
Soil
Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics...
, or wood
Wood
Wood is a hard, fibrous tissue found in many trees. It has been used for hundreds of thousands of years for both fuel and as a construction material. It is an organic material, a natural composite of cellulose fibers embedded in a matrix of lignin which resists compression...
splinters may be attached to the squib to simulate the "splash
Splash
Splash may refer to:* Splash , sudden disturbances on the surface of water* Splash, in erosion, is the detachment and airborne movement of small soil particles caused by the impact of raindrops on soils-Computing:...
" that occurs when bullets pierce different materials.
Although squibs were once used even for the simulation of bullet hits on live actors, such use has been largely phased out in favor of more advanced devices that are safer for the actor, such as miniature compressed gas packs. These alternate devices are often still referred to as "squibs" even though they do not use explosive substances. The devices (whether explosive or not) are coupled with small balloon
Balloon
A balloon is an inflatable flexible bag filled with a gas, such as helium, hydrogen, nitrous oxide, oxygen, or air. Modern balloons can be made from materials such as rubber, latex, polychloroprene, or a nylon fabric, while some early balloons were made of dried animal bladders, such as the pig...
s filled with fake blood and often other materials to simulate shattered bone
Bone
Bones are rigid organs that constitute part of the endoskeleton of vertebrates. They support, and protect the various organs of the body, produce red and white blood cells and store minerals. Bone tissue is a type of dense connective tissue...
and tissue
Tissue (biology)
Tissue is a cellular organizational level intermediate between cells and a complete organism. A tissue is an ensemble of cells, not necessarily identical, but from the same origin, that together carry out a specific function. These are called tissues because of their identical functioning...
.
Squibs are used in emergency
Emergency
An emergency is a situation that poses an immediate risk to health, life, property or environment. Most emergencies require urgent intervention to prevent a worsening of the situation, although in some situations, mitigation may not be possible and agencies may only be able to offer palliative...
mechanisms where gas pressure needs to be generated quickly in confined spaces, while not harming any surrounding persons or mechanical parts. In this form, squibs may be called gas generator
Gas generator
A gas generator usually refers to a device, often similar to a solid rocket or a liquid rocket that burns to produce large volumes of relatively cool gas, instead of maximizing the temperature and specific impulse. The low temperature allows the gas to be put to use more easily in many...
s. One such mechanism is the inflation of automobile
Automobile
An automobile, autocar, motor car or car is a wheeled motor vehicle used for transporting passengers, which also carries its own engine or motor...
air bags. In military aircraft
Military aircraft
A military aircraft is any fixed-wing or rotary-wing aircraft that is operated by a legal or insurrectionary armed service of any type. Military aircraft can be either combat or non-combat:...
, squibs are used to deploy countermeasures, and are also implemented during ejection
Ejection
Ejection may refer to the following:* Ejection seat, safety device typically used to escape an aircraft in-flight.* Ejection , the act of officially removing someone from a game....
to propel the canopy and ejection seat away from a crippled aircraft. They are also used to deploy parachute
Parachute
A parachute is a device used to slow the motion of an object through an atmosphere by creating drag, or in the case of ram-air parachutes, aerodynamic lift. Parachutes are usually made out of light, strong cloth, originally silk, now most commonly nylon...
s. Squibs are also used in automatic fire extinguishers, to pierce seals that retain liquids such as halon
Halon
Halon can refer to:* Haloalkane, or halogenoalkane, a group of chemical compounds consisting of alkanes with linked halogens. In particular, bromine-containing haloalkanes.* Halomethane fire extinguishing systems...
, fluorocarbon
Fluorocarbon
Fluorocarbons, sometimes referred to as perfluorocarbons or PFCs, are organofluorine compounds that contain only carbon and fluorine bonded together in strong carbon–fluorine bonds. Fluoroalkanes that contain only single bonds are more chemically and thermally stable than alkanes...
, or liquid nitrogen
Liquid nitrogen
Liquid nitrogen is nitrogen in a liquid state at a very low temperature. It is produced industrially by fractional distillation of liquid air. Liquid nitrogen is a colourless clear liquid with density of 0.807 g/mL at its boiling point and a dielectric constant of 1.4...
.
History
Scott v. Shepherd 96 Eng. Rep. 525 (K.B. 1773) Squibs are mentioned in a prominent tort case from eighteenth-century England. A lit squib was thrown into a crowded market by the defendant, and tossed from bystander to bystander until it exploded in the plaintiff's hands.Squibs were originally made from parchment
Parchment
Parchment is a thin material made from calfskin, sheepskin or goatskin, often split. Its most common use was as a material for writing on, for documents, notes, or the pages of a book, codex or manuscript. It is distinct from leather in that parchment is limed but not tanned; therefore, it is very...
tubes, or the shaft of a feather
Feather
Feathers are one of the epidermal growths that form the distinctive outer covering, or plumage, on birds and some non-avian theropod dinosaurs. They are considered the most complex integumentary structures found in vertebrates, and indeed a premier example of a complex evolutionary novelty. They...
, and filled with fine black powder. They were then sealed at the ends with wax. They were sometimes used to ignite the main propellant charge in cannon
Cannon
A cannon is any piece of artillery that uses gunpowder or other usually explosive-based propellents to launch a projectile. Cannon vary in caliber, range, mobility, rate of fire, angle of fire, and firepower; different forms of cannon combine and balance these attributes in varying degrees,...
s.
Squibs were first used to simulate bullet impacts in the 1955 Polish film Pokolenie by Andrzej Wajda, where for the first time audiences were presented with a realistic representation of a bullet impacting on an on-camera human being, complete with blood spatter. The creator of the effect, Kazimierz Kutz, used a condom with fake blood and dynamite.