Detonators
China currently makes cardboard and powdered aluminium or magnesium may
paper shelled detonators (both plain and also be inserted as a flash charge over the
electric), sold by a Hong Kong based main charge; then the open end has a
company. The shell walls of these length of safety fuse inserted into it, and
detonators are even less dense than the the shell mouth is sealed with epoxy.
plastic ones, and consequently more For an electric detonator, the same
difficult to identify. The leg-wires of the procedures are followed as above, but an
electric ones would significantly aid in electric igniter is substituted for the safety
detection (by X-ray or metal detector) and fuse. This can be readily improvised from a
in their identification. The plain type, (non- flashlight (“torch”) bulb. By carefully breaking
electric for use with safety fuse), can be the glass bulb, the filament generally
Assorted detonators very difficult for a screener to identify. remains intact. The bomber will test it for
A slight darker band of heavy metal salts in electrical continuity, to be sure it has not
be somewhat difficult to identify. A the centre area would help identify this broken. A thin wire is soldered to the side of
determined and skilled bomber can detonator. The paper or cardboard practically the bulb’s metal base, and another thin wire
camouflage the metal shell, wires or shock disappears on X-ray, and because of the lack is soldered to the lead tip of the base.
tube in such a way as to make them quite of metal, would not be detectable, even in The filament is coated with a mixture of
difficult to identify and interpret, especially if quantity, by a metal detector. black powder and glue, allowed to harden
there are many other items in a piece of A newer class of detonators in wide use to form a “match”, and is then inserted into
luggage that tend to hide or overlap small for certain specialised applications, do not the shell mouth against the explosive
items. The angle through which the luggage contain primary high explosives. Instead of charge. A seal of epoxy cement or putty is
travels through the beam(s) can also serve containing a standard incandescent applied and allowed to harden, binding the
to further confuse the screener. The metal filament type bridgewire in the closure plug base of the light bulb igniter into the
frame of some types of luggage can provide assembly, they contain an exploding detonator shell mouth.
good cover for the shell and wires. bridgewire. The metal foil bridgewire While not 100% reliable due to lack of
Almost all detonator shells are made of requires a high electrical energy input, quality control, the trained bomber will
aluminium, but a significant proportion is causing the bridgewire to literally explode employ redundancy and use two detonators
made of copper, for certain types of forward against the explosive charge with in parallel in the circuit – in case one fails.
blasting requirements. There are also which it is in contact. This transfer of Note that some manuals on improvised
composite metal special purpose type energy initiates the explosive. explosives show a pair of wires entering
shells. They can be partly aluminium, partly There are also newer detonators through a hole in the centre; others show
brass or copper; the tubes are telescoped (introduced within the past couple of years one wire entering each end of the shell,
into each other and mechanically crimped by several manufacturers), that have sealed in place, with the filament igniter in
together by a series of ring “stab” crimps. programmable miniature circuitry in the the centre of the shell. This latter design is
On X-ray, particularly colour X-ray, the centre section. These detonators can only similar to a design used in early
different density materials will show slight be fired by a special exploder coded to the manufactured electric detonators.
differences. Some manufacturers make circuitry in the detonator shell. The mid The point is, screeners should also be
detonator shells from steel or nickel. portion will look more complex and bulkier trained to recognise different improvised
on X-ray than a standard detonator. detonator designs and materials. This
Unusual Detonators applies to recognition of such items in
Plastic detonator shells have been used in Improvised Detonators hand-searched luggage, and exposure to
some French and Yugoslav military anti- There are several American commercial their X-ray signatures. Their X-ray images
personnel mines, and are available on the publications and a number of Internet are somewhat different than standard
black market trade in military ordnance. A U.S. manuals that provide detailed instruction on types of manufactured detonators.
company makes plastic detonators for use in procedures for improvising detonators, using
oil wells. The shell walls are about the same locally obtained materials and chemicals.
thickness as metal detonators, but less dense A common method starts with taking an
and more difficult to detect on X-ray. empty ammunition cartridge (with the primer The author is Director
Plastic shell detonators that contain lead intact); a small casing from a 5.56X45mm or of Securesearch, Inc.,
azide, lead styphnate or mercuric fulminate a 7.62X39mm round would work well. Toronto, Canada. He
will show on X-ray as a characteristic dark An alternative approach is to use a small is a member of
area, due to the increased density of the diameter, thick-walled metal tube (copper, the International
heavy metal salts compared to the shell wall. brass, aluminium or steel, as available). Association of Bomb
This area can be very tiny, if it only comprises One end is then sealed with epoxy cement Technicians and
a flash charge or match section within the or epoxy putty, or it is just crimped shut in Investigators (IABTI),
shell, and is likely to be completely the jaws of a vice. Any of several and the Canadian Society of Forensic
camouflaged by other luggage items. improvised explosives can be used as the Science. His company manufactures inert
Cardboard and paper shell detonators filler charge, including TATP, mercuric explosive and IED training aids – many of
have been made for military use by Former fulminate or tightly packed black powder. which are in use training airport security
Soviet Union (FSU) countries, the Former If the bomber wishes to make a non- screeners, around the world. He can be
Yugoslavia and China. electric detonator, a small amount of contacted at: bkoffler@securesearchinc.com
16 Register now for FREE instant access to ASI online by visiting www.asi-mag.com February 2009 Aviationsecurityinternational
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