Base charge explosive system application

A detonator (30) which includes a tubular housing (32) with a bore (36) in which is formed a compartment (42), a first frangible container (44) inside the compartment (42), a first quantity of a first material (A) inside the first container (44), a second frangible container (46) inside the compartment (42), a second quantity of a second material (B) inside the second container (46), and an actuating mechanism (34) which is operable to break the first container (44) and the second container (46) thereby to allow the first material (A) to contact the second material (B) and form an explosive composition inside the compartment (42) characterised in that the housing (32) has a mouth (38), to the bore (36), which is connectable to an initiating source (104) in that inside the bore (36), a time delay composition (48) is exposed to the mouth (38), and a primary explosive (90) is located between the time delay composition (98) and said compartment (42), in that a safety device (80) is provided to prevent inadvertent breaking of the first container (44) and of the second container (46) and in that the explosive composition is formed in a period which is not less than one minute after the first material (A) contacts the second material (B).