Stink bomb

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A stink bomb or stinkbomb is a device designed to create an unpleasant smell. They range in effectiveness from simple pranks to military grade chemical agents.

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Stink bombs

At one end of the spectrum, relatively harmless stink bombs consist of ammonium sulfide, which smells strongly of rotten eggs. When exposed to air, the ammonium sulfide reacts with moisture, hydrolyzes, and a mixture of hydrogen sulfide and ammonia is released. Other popular substances on which to base stink bombs are thiols with lower molecular weight, e.g., methyl mercaptan and ethyl mercaptan — the chemicals that give odor to skunks and are added to natural gas. A variation on this idea is the scent bomb, or perfume bomb, filled with an overpowering "cheap perfume" smell. Prank stink bombs and perfume bombs are usually sold as a 1- or 2- ml sealed glass ampoule, which can be broken by throwing against a hard surface or by crushing under one's shoe sole, thus releasing the odorous liquid contained therein. This liquid is also sold in a spray bottle as Fart Spray, which serves the same purpose, but allows it to be applied to objects and people. Another variety of prank stink bomb comprises two bags, one smaller and inside the other. The inner one contains a liquid and the outer one a powder. When the inner one is popped by squeezing it, the liquid reacts with the powder, producing hydrogen sulfide, which expands and pops the outer bag, releasing the putridity.

At the other end of the spectrum, the governments of Israel and the United States of America are developing stink bombs for use by their law enforcement agencies and militaries as riot control and area denial weapons. Using stink bombs for these purposes have advantages over traditional riot control agents: unlike pepper spray and tear gas, stink bombs are believed not to be dangerous, and they are effective at low concentrations.

The most effective stink bombs are those that contain a mixture of several stenches of biological origins. The biological odors used – vomit, human waste, body odors, burnt hair, and rotting garbage – are found universally revolting by people of all cultures. A mixture of various odors is more effective over time than a single odor, because it is much easier to acclimate to individual smells; a mixture therefore lasts longer and offers a greater impact.

The Guinness Book of Records [1] lists two smelliest substances. One is the "US Government Standard Bathroom Malodor", a vile mixture of eight chemicals with stench resembling human feces, only much stronger, designed to test the efficacy of deodorizers and air fresheners. Another one, "Who me?", is a mixture of five sulfur-containing chemicals and smells like rotting food and carcasses. "Who-me?" was designed during World War II, for use by the French Resistance to humiliate the German soldiers.

[edit] Chemicals used

Typically, lower molecular weight volatile organic compounds are used. Generally the higher molecular weight for a given class of compounds, the lower volatility and initial concentration but the longer persistence. It should be noted that some chemicals (typically thiols) have a certain concentration threshold over which the smell is not perceived significantly stronger; therefore a lower-volatility compound is capable of providing comparable stench intensity to a higher-volatility compound, but for longer time. Another issue is the operating temperature, on which the compound's volatility strongly depends. Care should be taken as some compounds tend to be toxic in higher concentrations.

The most often encountered compounds are:

Thiols
- Methanethiol (used rarely, it is a gas and therefore more difficult to handle than liquids)
- Ethanethiol
- Propanethiol
- Butanethiol, Eau de skunk
- Pentanethiol
Other sulfur compounds
- Hydrogen sulfide, smelling of rotten eggs
Carboxylic acids
- Propanoic acid, smelling like sweat
- Butanoic acid, strong foul smell, effective and long-lasting
- Pentanoic acid
- Hexanoic acid, smelling of cheese
Aldehydes
Amines
- Ethylamine, fishy smell
- Putrescine, smelling of rotten meat
- Cadaverine, smelling of rotten meat
Heterocyclic compounds
- Indole
- Skatole, smelling of faeces