"A primary explosive is an explosive that is extremely sensitive to stimuli such as impact, friction, heat, static electricity, or electromagnetic radiation. A relatively small amount of energy is required for initiation. As a very general rule, primary explosives are considered to be those compounds that are more sensitive than PETN. As a practical measure, primary explosives are sufficiently sensitive that they can be reliably initiated with a blow from a hammer; however, PETN can usually be initiated in this manner, so this is only a very broad guideline. Additionally, several compounds, such as nitrogen triiodide, are so sensitive that they cannot even be handled without detonating.
Primary explosives are often used in detonators or to trigger larger charges of less sensitive secondary explosives. Primary explosives are commonly used in blasting caps and percussion caps to translate a physical shock signal. In other situations, different signals such as electrical/physical shock, or in the case of laser detonation systems, light, are used to initiate an action, i.e., an explosion. A small quantity, usually milligrams, is sufficient to initiate a larger charge of explosive that is usually safer to handle.
Examples of primary high explosives are:
- Acetone peroxide
- Ammonium permanganate
- Azo-clathrates
- Copper acetylide
- Diazodinitrophenol
- Hexamethylene triperoxide diamine
- Lead azide
- Lead styphnate
- Lead picrate
- Mercury(II) fulminate
- Nitrogen trichloride
- Nitrogen triiodide
- Nitroglycerin
- Silver azide
- Silver acetylide
- Silver fulminate
- Sodium azide
- Tetrazine
- Tetraamine copper complexes
- Tetrazoles
Examples of secondary explosives include TNT and RDX.
Tertiary explosives, also called blasting agents, are so insensitive to shock that they cannot be reliably detonated by practical quantities of primary explosive, and instead require an intermediate explosive booster of secondary explosive. These are primarily used in large-scale mining and construction operations, and in terrorism.
ANFO is an example of a tertiary explosive.
Low explosives are compounds where the rate of decomposition proceeds through the material at less than the speed of sound. The decomposition is propagated by a flame front (deflagration) which travels much more slowly through the explosive material than a shock wave of a high explosive. Under normal conditions, low explosives undergo deflagration at rates that vary from a few centimeters per second to approximately 400 metres per second. It is possible for them to deflagrate very quickly, producing an effect similar to a detonation. This can happen under higher pressure or temperature, which usually occurs when ignited in a confined space.
A low explosive is usually a mixture of a combustible substance and an oxidant that decomposes rapidly (deflagration); however, they burn more slowly than a high explosive which has an extremely fast burn rate.
Low explosives are normally employed as propellants. Included in this group are gun powders and light pyrotechnics, such as flares and fireworks. "
After reading through this, we realised that smoke bombs don't count as explosives. However we do have an alternative way if we have any problems with the materials we wish to use.
-Information taken from wikipedia.
