Hexamine fuel tablet

A hexamine fuel tablet is a form of solid fuel in form. The tablets burn smokelessly, have a high energy density, do not liquefy while burning and leave no ashes. Invented in Murrhardt, Germany, in 1936, the main component is hexamine, which was discovered by Aleksandr Butlerov in 1859. Some fuel tablets use 1,3,5-trioxane as another ingredient.

A number of alternative names are in use, including heat tablet and Esbit. Esbit is a genericized trademark as it is used to refer to similar products made by other companies. In most countries from the former Soviet bloc this is known as "dry alcohol".

The tablets are used for cooking by campers, the military and relief organizations. They are often used with disposable metal stoves that are included with field ration packs. Backpackers concerned with ultra light gear tend to buy or make their own much lighter stove. An Esbit beverage-can stove can be made by cutting off the bottom of an aluminum soft drink can, and turning it upside down to support the fuel tablet. A pot can be supported above this with a circle of chicken wire or metal tent pegs. The burning tablets are sensitive to wind, so a simple windscreen should be used, such as a strip of aluminum foil curved in a circle around the pot and stove. If necessary, the fuel tablet can be placed on a rock or on the dirt, with a pot supported above it by rocks, but this is less than ideal.

Another common use is to provide a relatively safe (see disadvantages below) heat source for model steam engines, such as those manufactured by Wilesco and Mamod, and other external combustion engines such as Stirling engines and pop pop boats.

Hexamine is prepared by the reaction of formaldehyde and ammonia. In an acid environment hexamine is converted to toxic formaldehyde, which is their main hazard for toxicity by ingestion.

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