In my Yuletide Ives’ Trail Winter Hike article, I mentioned the use of Esbit/hexamine stoves as an effective means for cooking meals in extreme conditions. This post is a follow-up and I will go through the process of making a DIY Esbit burner that is very light, so that my readers will be able to build their own if they so wish.
I shall first start off by saying that the terms “winter conditions”, “cold weather”, and (to a degree) “winter camping” tend to be thrown around in many discussions without much thought to the specific environment of that particular location. It should be understood that the winter temperatures in a humid-sub-tropical climate like that of Georgia will be relatively mild compared to more northern latitudes in a sub-temperate or temperate environment. Of course, this is not to say that more southern locations don’t get dramatic temperature drops from time to time during the winter season, nor that northern climates always have colder winter temperatures in comparison. Higher altitudes such as hills and mountains also play a role here because they can have their own micro-environments that are similar to climates further north. The Appalachian Mountain range is a perfect example of this. Also, it should be noted that approximately every 1000 ft/305 m in elevation gain, the temperature drops an average 3.5 F/ 1.95 C.
When I refer to “winter conditions” and “cold weather”, I am referring to temperatures below 32 F/0 C, which is to be expected during the winter season here in the Northeastern region of the US, as well as other northern latitudes across the States and around the world. As such, backpackers and other outdoor enthusiasts in these areas need reliable cook stoves that are capable of functioning efficiently below the freezing mark.
There are tons of videos and articles on the net dedicated to DIY alcohol stoves, usually made from pop cans. The advantage to these stoves such as these is that they are often easy to make, inexpensive, and ultralight. For that reason, they are extremely popular in the outdoor community. However, alcohol as a fuel performs rather poorly in conditions below the freezing mark. The reason for this is that the alcohol doesn’t vaporise as efficiently as it does in warmer temperatures. I have learned the hard way that denatured alcohol just doesn’t work in the winter conditions of my region. At 18 F/ -8 F, it will not ignite with a direct flame. Even if I got it to ignite, I’d be wasting time trying in futility for water to be brought to the boil.
Esbit fuel, on the other hand, is made primarily from a chemical compound called Hexamethylenetetramineis (molecular formula – (CH2)6N4), more commonly known as hexamine. It was designed to function in extreme conditions, including sub-0 F temperatures, giving off minimal smoke, and leaving hardly any residue from the combustion – and it is for these reasons that militaries around the world were quick to adopt hexamine tablets as a means for soldiers to prepare their meals in the field. Unlike alcohol, the tablets do need open flame to be lit…sparks from a ferrocerium rod won’t cut it.
Other benefits to using Esbit/hexamine tablets is that the fuel itself is relatively light and inexpensive (the cost will vary between different companies such as the Esbit brand and Coughlan’s). Burn times depend on the size of the tablet itself, but generally-speaking each tablet will maintain flames for around 10 minutes. However, in my own experience, hexamine fuel will give off some white smoke when a pot or pan is placed over the flames, and there is a distinctive fish-like smell that some people may find off-putting. Because of the fumes, if you like to cook inside your shelter, I strongly recommend you maintain adequate ventilation – leave the tent/tarp flap open. Burning hexamine tablets also tends to leave a rather sticky coating on the bottom of your cook pot/pan.
*** I should also mention that some people have an allergic reaction to hexamine through skin contact, so be aware ***
All this said, many of the Esbit/hexamine burners and stoves out there on the market I have found to be either too heavy for lightweight backpacking, or too expensive for what they are. Unfortunately, there isn’t a lot of information online regarding DIY hexamine stoves, but on the other hand this allowed me to experiment through trial-and-error, coming up with a design that has proved to be successful.
Now then, on with the construction:
To make the stove, you will need a thumbtack, a round awl or an ice pick (a small nail also works), a file, a permanent marker, and a 3 oz cat food can. Optional items include a 5/16 inch/8 mm hole punch, a straight edge/ruler, some medium grit sandpaper, and tin snips or wire cutters.
Empty the can and clean it out. The basic idea behind the construction is to create optimal ventilation by creating 64 holes all around the can, with 4 rows (or levels) of 16 holes. With the permanent maker, start at the bottom making 16 dots all around. This will guide us when we punch-out the holes.
They don’t have to be perfectly placed – airflow is more important than neatness. However, I have found that making the largest holes at the bottom, gradually decreasing in size towards the top, seems to work the best for optimal airflow. You don’t have to mark the holes one in line which each other in a vertical sense as depicted above – if you wish, you can alternate them as shown in the first picture. Once you’ve marked all the holes, take the thumbtack and punch through all the dots. If you have a 5/16 inch/8 mm hole punch, you can use that for the bottom row.
With all 64 holes made, carefully punch into the holes with a round awl, an ice pick, or a small nail. This will widen them out a little bit. We can’t leave it at that, though – the tablets will still need a lot more ventilation intake. So the next step is to take a file, and use the tang to carefully widen the holes (a twisting motion helps), making the holes larger at the bottom of the stove, gradually decreasing in size for each row towards the top. The top row can be left alone. The diameter of the holes in each row needn’t be any exact measurement, but for those of you who are nit-picks, I’ll include some dimensions. Bottom row: 5/16 inches/8 mm; second row: 1/4 inch/6.35 mm; third row: 1/6 inch/4.25 mm; top row: 1/8 inch/3 mm. Again, you don’t need to be ultra-precise…this is just a rough guide to follow.
Once all that has been done, the stove is complete :). It will be able to burn two hexamine tablets at a time, though for my purposes I only use one block at a time.
You can modify this stove for convenience by cutting out an opening through which you can insert the fuel without having to remove your cook pot or pan from the stove itself. This modification isn’t essential to the stove’s performance.
Take some tin snips or wire cutters, and carefully cut out an opening 3 holes tall from the bottom, and 3 holes wide. This will be approximately 7/8 inches/2.25 cm vertical by 1 inch/2.5 cm horizontal. With that done, clean up the edges with the file and grind off any remaining sharp bits with the sandpaper.
And that’s it! 😀
This stove is ultralight weighing less than 0.5 oz/14 g, which is probably lighter than most of what is on the market. It also doesn’t need a pot stand because of its well-ventilated construction. This stove, combined with my DIY ultralight cook pot (See Sintax77’s video on how to make it), weighs only just over 3 oz. That is impressively light, and perhaps the best part is that the total cost of the cook system (pot and stove) is around $10…it can be put together for under $10 depending on where you live and if you don’t mind shopping around. In any case, $10 for the cook kit plus around $7 for 12 hexamine tablets is very budget-friendly. A titanium cook system with a pot and hexamine stove of a similar weight would cost a lot more.
I should mention that this stove performs better if it is placed on some aluminum foil or a can lid of 3 inch/7. 25 cm diameter or so when there is snow on the ground. This will help prevent it sinking into the snow. Using a windscreen is also recommended to help it burn more efficiently in windy conditions.
Lastly, some people have complained that hexamine tablets “don’t work” in cold weather. My experiences and observations differ. I have used Esbit/hexamine fuel in low temperatures around the 10 F/-12 C mark without any issues, and I have found it to be a reliable cooking source in winter.
And on a final note, I am well aware that this design isn’t the first DIY hexamine stove to be made. I am posting this simply because the design is functional, cost effective, and would benefit anyone looking into alternative cooking sources for winter camping. That said, I have come across a few other DIY versions out there, and so I will post them here as a resource if any of you are feeling particularly adventurous.