C-4 block in The Flame basement in ("Enter 77") (promotional still).
C-4, short for composition 4, is a plastic explosive developed in the 1960s as an improvement to a pre-existing plastic explosive called Nobel 808. C-4 is a combination of explosive, a plastic binding agent, a plasticizer, and a marking chemical added to ease detection.
C-4 used for Sayid's suicide bombing mission in ("The Greater Good").
Like all plastic explosives, C-4 is extremely stable. Called an insensitive explosive, C-4 is very difficult to trigger by accident. Impact and fire are separately not enough to detonate C-4, but the combination of the two can create the necessary circumstances for detonation. Fire will cause C-4 to burn with very high heat, even underwater, and was often used by U.S. troops in Vietnam to cook food. C-4 is 1.34 times more explosive than TNT.
Uses in the series
- Essam Tasir and Sayid were supposed to carry out a suicide bombing mission with a truck full of the C-4 explosive. Essam killed himself before they could carry out the plan. ("The Greater Good")
- C-4 was the explosive used in the self-destruct system built into the Flame communications station. Several blocks of C-4 were strategically placed at the join between the subsurface section wall and the ceiling. The size of the blocks indicated a standard two-kilogram demolitions charge, common to military units. A series of these blocks would be more than sufficient to destroy the station. ("Enter 77")
- Locke removed at least one of the C-4 blocks from the Flame station before it was destroyed. Rousseau suggested using this explosive to destroy one of the pylons in the sonic barrier, but the plan was deemed too dangerous. ("Par Avion")
Michael's C-4 toolcase as seen at Lost: The Auction.
- Returning to the Island on the Kahana, Michael was sent a toolbox filled with explosives. He took the toolbox down to the engine room and prepared to activate the bomb. Libby briefly appeared to him and told him not to do it, but she disappeared and Michael shook off the apparent hallucination. He punched in a detonation count, but at the end of a short countdown, rather than detonating, the bomb popped up a flag reading "NOT YET". ("Meet Kevin Johnson")
- A C-4 bomb was found in the armory of the Kahana. ("There's No Place Like Home, Part 1") Desmond Hume and Jin Kwon's efforts to defuse the bomb were unsuccessful, though Michael Dawson did manage to delay the bomb's detonation by freezing its battery with a tank of liquid nitrogen. A "dead man's switch" device comprising a heart rate monitor and radio transmitter strapped to Martin Keamy's left arm caused the C-4 to explode, upon Keamy's death in the Orchid, sinking the Kahana and killing several innocent people, including Michael. ("There's No Place Like Home, Part 2")
C-4 used in Man in Black's bomb in ("The Candidate").
- Widmore had the Ajira plane rigged with C-4 as a trap for the Man in Black and his followers. However, the Man in Black discovered the explosive and used it, along with a watch taken from Wheeler, one of Widmore's men, to construct a bomb of his own. He hid it in a backpack given to Jack as part of his plan to kill all the Candidates after they captured Widmore's submarine. Jack discovered his plot, and only Jack, Hurley, Kate, Sawyer, and Frank survived the explosion and the subsequent sinking of the sub. ("The Candidate") ("The End")