Boiling water with an 8g stove

Meths stoves are odd little things — ultra-simple, ultra-lightweight, effective.  Hum, yes-but-no-but — they are all those things, except effective — on their own.  What's needed is a little attention to detail with focusing the heat from the burning meths onto the base and sides of your (my) titanium mug.

I bought the 8g + 22g meths-stove bundle from Bearbones Bikepacking back in May (2017) and I have been doing test-burns since then, trying to optimise my setup on the back patio, so that when I use it for real up a Welsh mountain then I am pretty certain it's going to work.  Most of my effort has gone into hand-crafting suitable windshields to go with my 400ml and 650ml titanium mugs.

IMPORTANT — DO NOT USE A DOUBLE-WALLED MUG!! Use ONLY a single-walled mug! If you try to boil water in a double-walled, insulated mug then it will explode and could hurt you very, very badly!

In perfectly still, warm weather, it is just about possible to get a boil out of the 8g stove just by lighting it and balancing the mug on top.  However, for even the slightest breeze then a windshield is absolutely necessary.  Having given this quite a bit of thought, these are my main requirements of a windshield:

  • It must protect the flame from sidewinds, but must also allow plenty of air in to provide oxygen for the burn.
  • It must funnel the hot combustion gases as far up the side of the mug as possible for efficient heating.
  • It must fit inside the mug for transportation and convenient packing.

The simplest way to "play" with designs is to use cheap and readily available disposable baking trays — a couple of quid from Tesco for two.  That's enough material to make four or six prototype windshields.

Making a windshield

The first thing is to measure the mug — the inside of the mug, including allowing a bit of room for the lid to push in.  Then cut a strip along the length of the bottom of the tray that is just the right width.  All you need is a good pair of kitchen scissors for this.  It does not have to be precise!

 Cut a section from each end to allow the mug handles to poke out

Cut a section from each end to allow the mug handles to poke out

Next, wrap this loosely around your mug — we need to find the handle locations, so we can cut a bit off the "top" of each end of this strip to allow us to place the mug on the burner.  Don't cut off too much — it's easy enough to trim more later.  We only want to go far enough down so that the handles just rest on the windshield, when the mug is placed on top of the burner — so remember to add on the height of the burner.  If you muck up your first one, it's easy enough to make a second.

 A well-used specimen showing the air gaps along the bottom, as well as the securing strip

A well-used specimen showing the air gaps along the bottom, as well as the securing strip

Then, along the bottom edge of the strip, cut 'tabs' and fold these up leaving three or four little feet, about 5mm tall — the gaps allow air to flow in and should be big enough to allow enough air for the burn, but small enough to prevent a crosswind blowing all the heat away, or blowing the flame out.

 A nice, even gap all the way around the mug to allow the hot combustion gases to rise

A nice, even gap all the way around the mug to allow the hot combustion gases to rise

Place your mug on top of your stove (no fuel for now) and shape your strip into a nice cylinder — leaving about 2-5mm gap all the way around your mug.  This does not have to be perfect, but it helps if the gap is even all the way around.  Use a paperclip to join the two end-tabs of the strip to hold it in a cylindrical shape.  I also paperclip a strip of tin foil to the windshield so that I can weight it down with a stone or similar, to keep it steady in the wind — as soon as you remove your mug when the water had boiled, the windshield will try to escape in the lightest breeze!

 I add a small extra shield on the windward side of the pot

I add a small extra shield on the windward side of the pot

For light breezes, I add a small extra shield on the windward side of the pot to prevent a strong breeze forcing too much air into the combustion cavity and either cooling the burn or blowing out the flame.  In stronger winds, I have a length of much-crumpled baking foil that I wrap around the pot + burner to keep the wind out and to keep it all warm — as fast as the burner is pushing heat into the bottom and sides of the pot, a strong, cold wind is removing it from the top, if you don't protect it somehow.  You just have to make sure you don't smother the burn.

 Finally, some boiling water

Finally, some boiling water

With a bit of practice I can reliably boil about 370ml of water in a 400ml mug in about six minutes.  Nothing about this method of boiling water is particularly quick, but when you're out in the countryside then you're supposed to take your time and enjoy the place you're in.

The small silver square in the photos is an off-cut of thin fibreboard (actually an old clipboard) that I have wrapped in tin foil.  This serves three important purposes:

  • To provide a stable base when boiling water out in the wild.
  • To provide a thermal barrier between the burner and the ground — the burner can get very hot!
  • To catch any spilt fuel and allow it to burn off safely, without setting fire to the ground below.

Setting it up

These meths burners all work the same way: there is an outer and an inner wall, and meths fills both the hole in the middle, as well as the gap between those two walls.  The heat from the flame in the middle, which is yellow and slow, eventually heats the meths causing a rush of vapour to be given off, which forces out of the row of pinholes just below the top edge.  When this ignites, the flame changes and becomes much hotter.  This is known as "blooming". 

You only put the pot onto the stove when it has reached its bloom point and is hot — too soon and it will extinguish; but don't hang about — a blooming stove will burn through all the meths very quickly if you don't put a pot on it, which limits the burn to just the ring of pinholes, extinguishing the main flame, and slowing fuel burn rate.

 Just at the bloom point, the flame gets a lot more exciting!

Just at the bloom point, the flame gets a lot more exciting!

To set the whole thing up, do the following:

  1. Find somewhere suitable to do your boil — flat, non-flammable, and preferably out of the direct wind.
  2. Place the baseboard down, with the stove on top, in the middle.
  3. Reshape the windshield to the size of your mug (plus a bit), paperclip it to that size and place it over the stove; weight the securing strip with a stone or something to stop it blowing away.
  4. Squirt meths into the stove until it's just below the inner breath-hole.  Place the burner back on the baseboard.
  5. Carefully ignite the main body of meths in the burner, being careful not to burn yourself or to ignite any nylon clothing you're wearing.
  6. Wait a minute or so for it to bloom.  You can be pouring water into your mug at this point.  I also add my teabag to the cup — I brew while it's boiling, not afterwards, since everything cools down so quickly when the burn finishes.
  7. As soon as it blooms, carefully place your mug onto the top of the stove.  Check for a few moments that the flame is still lit — it's easy to put the mug on too quickly, extinguishing the flame. I always separate the handles of my mug to let them sit in moving air and lose heat, otherwise it is very easy to burn yourself!
  8. Put any additional windshields in place, as necessary — you may need to hold them in place by hand, if it's very windy.
  9. Wait for it to boil.

If you add more fuel than you need, you'll just have to let it burn off — there is no way to rescue and reuse.

Also, if you're having trouble getting the stove started, squirt a little meths around the bottom of the burner on the board and light that — that will warm the metal of the stove and eventually ignite the main body, which in turn ignites the jets at the bloom point.

Packing it all away

The final part is packing it all away inside the mug.  Since the windshield may have rested on sheep-poo-riddled ground, as well as picked up splashes of meths, I prefer to not pack it right inside my mug.  Instead, I have a small yoghurt pot of about the right size, which I can keep the outside of clean (that's the bit that sits against the inside of the mug), and the dirty/smelly windshield and burner sit inside.  I usually drop a small stone into this plastic pot while it's empty, to prevent it blowing away.

 My inner pot, packed ready to go inside my mug

My inner pot, packed ready to go inside my mug

Remove the paperclip from the windshield and tighten the cylinder slightly so that it fits neatly inside the pot; put the small extra shield inside that, then bundle the burner — when it is cool — into the fold of the strong-wind tin-foil wrap, to stop it bouncing around, annoyingly.  Slip the lighter into the top and then slip the whole pot into the mug.

 Slip the inner pot, containing the shields, the burner and the lighter, into the mug

Slip the inner pot, containing the shields, the burner and the lighter, into the mug

Finally, secure the lid and handles using a couple of elastic bands — nice and simple.  The mug, including everything inside, weighs about 150g.  The baseboard weighs under 30g.  And that pot of fuel weighs about 120g — that's 300g all up.  The equivalent weight of a JetBoil, including fuel, is about 800g, plus the weight of a mug (95g) — using this micro-stove setup saves over half a kilogram of weight from your bikepacking kit, at the cost of being a lot more fiddly and a lot slower to boil water.

 The whole setup, packed away, ready to go on the bike.

The whole setup, packed away, ready to go on the bike.

Finally

So there you have it — an ultra lightweight method of boiling water that's good for about 20 cups at a fraction of the weight of something based on gas.  In truly foul weather then the JetBoil will win hands-down every time, but if you're in spring or summer and you have plenty of time then this is a much more satisfying way of making a cuppa!

Note that in very cold weather then winter gas is much easier to light than meths — meths you need to keep warm in your pocket before it will give off enough vapour to take a flame.

Finally, I use a lighter with a lock-on switch — this saves me burning my fingers trying to light the flame, because once the lighter is aflame then I can lock the flame on and then hold it by the other end when pointing it down into the stove to light the meths.  It's a little detail, but it does save melting all the hairs off the back of your fingers!

Nick Wilkinson

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