Primers and initiators are explosives with special properties and some of them can exhibit the characteristics of both high-order and low-order explosives. Most of them are high explosives and they are much more sensitive to friction, heat and shock than other forms of explosives. In some of these materials, physical impact or vibration can cause an explosion. Some are strictly deflagrating, but when confined they detonate. They are usually used in small quantities to initiate an explosion in another explosive material. Some high explosives cannot be detonated without the use of some other explosive to set up an initial shock wave and a few must have a booster charge.
A detonator is used to destroy ammunitions found in a captured Iraqi military truck halted by 3rd the Battalion, 1ST Marine Regiment, Regimental Combat Team 1 (RCT1) in Al Fajr, Iraq, in support of Operation Iraqi Freedom. 30 March, 2003.
Photo: Corporal Mace M. Gratz, USMC.
National Archives and Records Administration.
Still Picture Branch; College Park, Maryland.
Initiating explosives are very sensitive and that is why they are used - to set off an explosion in a less sensitive material. Although they explode easily, their explosions are usually not as powerful as other explosives. That is why they are not usually used as explosives themselves. Because of their sensitivity, they are usually only kept in small quantities and well away from other explosives.