Name: Esbit Solid Fuel Tablets
Importer (US): MPI Outdoors, 10 Industrial Drive, Windham, New Hampshire 03087
Website: www.mpioutdoors.com
Manufacturer: Esbit Compagnie GmbH, Hamburg, Germany
Website: www.esbit.net
Weight as claimed by importer (per tablet): 0.5 oz (14 g)
Weight as measured (from weight of twelve): 0.5 oz (14 g)
Note: These weights are inclusive of the blister packaging
Fuel energy per kilogram, as claimed by manufacturer (not tested): 31,300 KJ/Kg
Approx. fuel energy per tablet (reviewer calculations): 440 KJ (417 BTU, 105,000 calories). This is theoretically (assuming 100 percent efficiency) sufficient to raise 1.3 litres of water from room temperature, 68° F (20° C) to boiling (100° C, 212° F).

Introduction

Esbit tablets are a solid fuel containing hexamethylenetetramine (also known as hexamine) as stated on the box. They have been manufactured for about fifty years. The fuel is a white, waxy solid shaped into a small rectangular cake. In the form in which Esbit tablets are generally sold in this country, they are blister-packed (in thin clear plastic with a foil backing) in strips of three and are sold in boxes of twelve tablets. The manufacturer offers other configurations of blister pack, which seem not to be imported into the US.

The text on the box states the following (partial list):

Practically odorless
Non-toxic formula
Emits no harmful vapors
Leaves no ash residue
Generates 1400° F of heat [760° C]
12-15 minutes burn time per cube
One cube will bring 1 pint of water to a rolling boil in less than 8 minutes

However, in direct contradiction to the statement on the box regarding toxicity, the box bears a legend "Harmful if swallowed, call doctor."

What's the truth here so far as this is concerned? Hexamine itself can emit a variety of harmful gases, including formaldehyde, hydrogen cyanide, ammonia and oxides of nitrogen on combustion and repeated or prolonged contact can cause skin sensitization (source: International Programme on Chemical Safety, see website or literature for fuller hazard information). Formaldehyde, among other toxic effects, may precipitate asthma attacks.

However, this writer is asthmatic (chronic but in almost total remission) and has never experienced any ill effects from burning Esbit tablets. I have been careful not to inhale the fumes when using the fuel any more than possible. I believe (but as this information is proprietary, cannot demonstrate definitively) that hexamine is only part of the Esbit formula, and that there are other components that mitigate the (relatively mild) toxicity of hexamine.

Still, I would not cook with these tablets in any enclosed space (despite the fact that the manufacturer and distributor note that the tablets are used by NATO forces, and the tablets are used with certain kinds of model steam engines). I do have concerns that some susceptible individuals could experience health problems as a result of handling the tablets or inhaling the vapors when burning. Still, Esbit tablets are significantly less toxic and significantly more effective than trioxane, which is still used by the US Army in some situations. It should be noted that Esbit tablets may be easily blown out part-way through combustion, enabling fuel to be saved, while trioxane cannot be extinguished with any ease.

Testing background

I have used Esbit tablets for some years as a lightweight emergency fuel; for a backup fuel to alcohol on a through-hike; to prepare hot drinks at lunch in winter (lighter than a thermos); to prepare simple reconstituted meals on one and two day hikes; and as a fire-starter on the few occasions when I have a campfire (small, and in accordance with Leave No Trace principles)!

I have variously used the folding stove made by Esbit's manufacturer (weight circa three ounces, 85 g, on left in image), a construction of wire (weight at most 0.25 oz, 7 g) or no holder for that tablet at all, using either earth and rock (the least recommended method of use). The last method is obviously of minimal utility in winter, but I have achieved satisfactory results in appropriate conditions using all of these. One caveat: a windshield must be used when cooking with Esbit tablets, in my experience. I use a foil windshield from a MSR Rapidfire stove that has served me admirably well in a variety of applications for years, and which adds approximately an ounce (28 g) to the cooking kit. I usually use the tablets in conjunction with an MSR Titan kettle.

I have used the tablets at altitudes to 4000 ft (1220 m) and down to temperatures of 0° F (-18° C). One tablet on a cold winter day is sufficient to heat a mug of cocoa to the point where it needs to cool before being drunk (the combustibility of the tablets is not affected by temperature, which is not true of alcohol or gas, although I would never recommend Esbit for any winter trip where snow-melting was involved – it simply doesn't have enough power). I usually light the fuel using a Brunton Helios lighter in these conditions, and sprinkle a few flakes of paraffin-wax impregnated woodchips on top, which encourages a quick start to the burn. On a summer evening, the effort to cook with Esbit tablets is obviously considerably less.

Notes on the use of Esbit tablets

Much has been written on the efficiency of Esbit tablets for long-distance backpacking–see for example, the excellent discussion on Sgt. Rock's site. Based on my own quite considerable experience, Esbit tablets have proven to be a weight-efficient fuel for three-season backpacks of short to intermediate duration, although there are unquestionably trade-offs in convenience. For a long trek, ten days or more, I would almost certainly use alcohol (or, if feasible, a canister stove).

As a general rule, two to three tablets are sufficient for one full day for one person (and this is very much a one-person method of preparing hot food). That's a maximum fuel weight of 1.5 oz, 43 g, though this is really a little on the high side, and assumes a hot breakfast drink, perhaps a hot lunch and a hot supper of freeze-dried food, far more than I can usually be bothered with. This amount is roughly comparable to the weight of alcohol that would be needed for an equivalent amount of "cooking." The advantage, of course, is that only a minimalist stove is needed, but it should be clearly noted that the standard Esbit stove weighs about the same as many canister stoves (sans canister). This is why I use a small wire stove of the kind shown, which I have found (used in conjunction with the windshield) very effective and a substantial weight saving.

Esbit fuel burns fairly cleanly and indeed leaves a minimal stove residue, but does tend to leave a black deposit on pots (however, blackening of pot bases does make them slightly more efficient at heat absorption, so this is a non-issue so far as I am concerned). Despite the claims of the distributor that the tablets are odorless, they in fact have a pronounced "fishy" odor, which, while not offensive, makes it requisite to treat them as a foodstuff–they must be kept in a canister or bear-bag. Yes, bears will eat them if they can, as I know from direct experience when a bear-bag failed. There is also a pronounced odor when they are extinguished.

True cooking is not possible (or is, at least, very difficult) using Esbit tablets, as they are not an adjustable heat-source, but for those (like myself) who enjoy the freedom from kitchen chores when backpacking, this is no great loss. They are as quiet as alcohol and cannot leak into one's backpack, nor can they spill while filling the stove, both rather considerable advantages. The amount of packaging waste is quite minimal and indeed tablets can be carried loose in a Ziploc or similar container. Heating times with Esbit and alcohol are roughly equivalent, as I have found in side-by-side comparisons, though much depends on the alcohol burner used.

I do find the burn times stated on the packaging to be somewhat exaggerated. In my wire stove, a tablet rarely lasts more than ten minutes, though the time's slightly longer in the Esbit stove. Nor have I been able to duplicate the claim that it is possible to bring a pint of water to the boil in eight minutes, although that's usually rather more water than I would be heating in any case. As with alcohol stoves, a certain amount of patience is called for, but this is part of the pleasure, in my estimation.

One issue with Esbit tablets is cost. The price (as of this writing) is almost universally about fifty cents per tablet, or $1.50 per day, much more than alcohol or even canister gas. It's this factor, as much as anything else that makes me recommend the use of Esbit for shorter trips only. It should be noted that shipping Esbit tablets is not subject to any legal limitations of which I am aware.

Summary

Esbit tablets, despite some shortcomings and minor concerns about adverse health effects from vapors, are a viable and effective fuel for backpacking trips in mild weather (and as an emergency fuel in all weathers) provided that food preparation is kept extremely simple. Thermal output is not affected by ambient temperature, unlike most fuels. There is a low potential for fuel waste and the tablets can even be used, albeit inefficiently, without a stove. These unique advantages are offset to a degree by the cost of the tablets.

Reviewer Background

I hike regularly year-round in the Catskills, with occasional excursions to the Adirondacks and elsewhere. A hiker since my teens, I was born and grew up in rural Hertfordshire in England, moving to the US at age 19. Given the harsh winters of the region where I make my home (and the need to keep active or perish of boredom) I make frequent ascents of local peaks on snowshoes and crampons, with an occasional foray on cross-country skis. Nothing could be further removed from the landscape of my childhood.

I enjoy walking in all its manifold forms, from a simple stroll in the woods to multi-day backpack excursions. I through-hiked the Northville-Placid trail over ten days in 2003. Though by no means an extreme ultralight enthusiast, from spring to fall my preference is to carry a packweight of 12 pounds (5.5 kg), more or less. In recent years, I've rapidly moved to a philosophy of "lighter is better," within the constraints of budget and common sense.

Read more reviews of Esbit gear
Read more gear reviews by Edward Ripley-Duggan

Owner Review by Edward Ripley-Duggan