White in colour like plasticine to mould. Set off (i.e. explode) by a detonator or Det Cord thats been tied in a knot. The secret to good dems is to use the right amount for the job and of course be properly trained.
Saying "Oops, it go boom" is not it seems an acceptable excuse for blowing rather more up than you expected. When the Boss says "are you sure thats what you learnt on the Dems Course" don't say "Eh, what f*cking Dems course".
Can be used to instantly boil a cup of water. Break off small lump of PE4, place lump under mug of cold water, apply match (not detonator) and hey presto instant boiling water. A point to note...make sure the mug is metal. NB: Illegal.
Can also be used for fishing . NB: Illegal.