Basic Information
In modern usage the term solid fuel tablet typically refers to a block of hexamine. Technically you could apply the term to virtually anything solid, usable as fuel and in tablet form, but in practice it will be either hexamine or trioxane, and usually hexamine. Alcohol gels and similar things are also used, but are their own thing.
What you get is a block of white, wax like material with a mild chemical odour that ignites relatively easily from a naked flame and burns steadily with a good energy density and little smoke. As long as they are kept dry, they appear to survive indefinitely in storage and require no special technology with which to burn, meaning that they can be used with improvised cooking facilities or a variety of cheap, even disposable metal stoves as favoured by many armed forces. These tablets are also marketed as firelighters, in which role they can be used as a form of tinder to ignite larger piles of combustibles.
Disadvantages revolve around spoiling quickly if wet, leaving a greasy black residue on anything in contact with their flame, being mildly toxic and giving off formaldehyde when burned. Given the fumes it's usually best to cook food in a sealed pan or container - although a lot of purpose made outdoor food is designed to be cooked in mostly closed packaging anyway (either a tin, which is single pierced before heating or a bag which in some cases can be heated whilst sealed to at most requires a minimal piercing like the tin).
As noted, hexamine fuel is popular amongst many militaries and, based on their surplus, has also permeated deeply into civilian outdoor use, and although in recent years its prevalence has been challenged by flameless alternatives (due to their lower toxicity and the fact they do not give a concealed position away at night by generating a great deal of flame) their versatility continues to keep them in service for the foreseeable future (as an example, if I use a flameless ration heater to cook my compo bag, I have a hot compo meal and a dead ration heater. If instead I boil that bag over a hexy stove, I'm left with a hot compo meal, a pint of boiling water, a charred stove and a greasy mess tin. Traditionally an infantryman has a great man uses for hot water).
Since their invention, these tablets have also been re-purposed as fuel for miniature steam engines such as those used in toy trains and boats.
Sources
Game and Story Use
- In the modern era, ubiquitous in civilian outdoors shops and still very common in military supplies (in which case it will generally be accompanied by a folding metal stove). Any character with an outdoor lifestyle or a military background of almost any kind should be familiar with the stuff and there should be plenty of it about for a while after the end.
- Hexy was actually invented in the late C19, but took a while to become widespread - prior to WW2 it might take experience with specialist units to be familiar with it, mountain regiments, marines, prototype special forces or scientific expeditions all have potential; anywhere where added expense might be justified to acquire a highly mass-efficient fuel.
- As for the stove, the "improvised cooking facilities" above have been known to be fashioned from folded tent pins, barbed wire, chicken netting and cut-down food or beverage cans. With a little ingenuity, and a tolerance for limited service life, it's really easy to make a hex cooker.
- For comparison, the British Army was issuing "solidified alcohol" to troops in WW1 for use in trench stoves in the front line.
- Note the downsides - botched survival skill roles may lead to poisoning or just wet and unresponsive hexy.
- It is possible to make explosives from hexamine. No. We will not tell you how. Your character may be able to work it out by buying up the right skills.
- Presumably they might also be used like dog biscuits to tame small, sub-sapient fire elementals and similar things or fed to steampunk automatae.