By GAVIN ENGLISH
It looks like uncooked dough but it is deadly and can be bought easily enough.
The plastic explosive, which Indonesian authorities believe was used in the Bali bombings, is known as C4.
It was C4 that shoe-bomber Richard Reid put into his footwear when he tried to blow up an American Airlines jet.
It was also used in the bombing of the USS Cole in Yemen in 2000.
C4, a code named given it by the US military, has become the explosive of choice for terrorists because it is odourless, hard to detect and can be moulded to any shape needed.
It can fit into any container, be squeezed into holes or stuck on a wall.
While it is usually used by the military, including the US Army, it can also be bought over the internet in 25kg barrels.
It costs about NZ$50 a kilogram, but English company Ribbands Explosives advertises on the net a special offer discount on orders of more than 16 tonnes.
"Explosives authorisation" and an "end-users certificate" are required to buy C4.
Individual suppliers mark the explosive with a unique chemical solution allowing blast residue to be traced to the supplier.
Plastic explosives require a detonator. These come in a number of forms and can be set off by a timer or remote control.
New Zealand bomb experts say C4 produces a fireball of between 3000 and 4000C, melting and searing everything in its path.
C4 was originally developed in Czechoslovakia, behind the Iron Curtain, but was refined and stabilised by the American military, which added rubber compound so it became malleable and easily used.
It can be cut with a knife. More worryingly, metal shards can be pressed into the explosive to increase its lethal force.
C4 can be safely stored for at least 10 years.
The material is used by the military for demolitions, gap creation and in some mines. It is not used in any civilian applications.
Advertisements usually warn that C4 is highly explosive and its fumes are poisonous.
This week, both Indonesia's intelligence chief and national police chief confirmed that C4 was used in the Kuta blast.
Police chief Da'i Bachtiar said the larger of two blasts appeared to have been caused by C4 plastic explosive, suggesting a relatively sophisticated device
Police and witnesses have described a small blast at Paddy's bar followed by a much larger explosion, possibly a car-bomb, outside the Sari nightclub.
The senior custodian at the Waiouru Military Museum, Sergeant Brenton Beach, said car-bombs were particularly deadly for several reasons.
"Not only can you pack a lot of explosives into a car, you can also fill them with metal and other things that act as shrapnel.
"You can also add gases such as hydrogen and helium to increase the blast."
He said it was almost impossible to detect a car laden with explosives.
"They look very innocent. You can just park it up and walk away.
"You don't have to put the explosives on the back seat. You can pack them in the boot, around the motor or in the car's panels."
Bali messages and latest information on New Zealanders
New Zealand travellers in Bali, and their families around the world, can exchange news via our Bali Messages page. The page also contains lists of New Zealanders in Bali and their condition.
Foreign Affairs advice to New Zealanders
* Travellers should defer travel to Bali
* NZers in Bali should keep a low profile and remain calm
* Foreign Affairs Hotline: 0800 432 111
Feature: Bali bomb blast
Related links
C4 - the terrorist's bomb of choice
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