Explosive booster

An explosive booster acts as a bridge between a low energy explosive and a low sensitivity (but typically high energy) explosive. It increases the energy of an initiating explosive to the degree sufficient to trigger the secondary charge.

Unlike C4 plastic explosive, not all explosives can be detonated simply by inserting a detonator and firing it.

An initiator such as shock tube, cannon fuse (or even a conventional detonator) does not deliver sufficient shock to detonate charges comprising TNT, Composition B, ANFO and many other high explosives. Therefore, some form of "booster" is required to upgrade the energy released by the detonator so that the main charge will detonate.

Tetryl was once a very popular chemical for booster charges, particularly during World War II, but has been largely superseded by other compositions e.g. a small cylinder or pellet of pure RDX or PETN (slightly larger than the actual detonator) into which the detonator itself is inserted.

Note: booby traps and improvised explosive devices frequently use plastic explosive as the booster e.g. some semtex stuffed into the empty fuze pocket of a 120mm mortar shell.

When encountered in connection with artillery shells or air dropped bombs, a booster charge is referred to as the gaine. See detonators.