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Alcohol Stoves: Timing Your Boil

Measuring Denatured Alcohol for a Pepsi-can Stove

Long-distance AT hikers love to obsess over pack weight and gear choices. Eventually any extended or thru-hike planning effort will come to a decision on what stove to bring. For me, this was quickly remedied by the statistics on what kind of stove successful thru-hikers used and a huge percentage of those that finish use simple alcohol stoves.
The reasons are abundant:

  • Low (or no) cost.
  • Fairly simple to use.
  • The denatured alcohol fuel(DN) although not the lightest possible fuel, is available in any hardware store.

There are two downsides to the Pepsi can-style DN stoves.  They can be finicky in windy situations and have different heating properties based on the ambient temperature. I found that with enough practice, a good butane lighter and a good windscreen, windy cooking was not a problem. Temperature, however, is a different issue.

Since I do freezer bag cooking on the trail, I pre-mix dehydrated food in boiled water increments. Mostly in one cup units, but sometimes in 1 1/2 and 2 cup.Those ever-popular rice side meals are two cups per pouch. To assist in meal prep and to save fuel and weight, I've developed a technique for using EXACTLY the minimum amount of fuel. Remember that the instant your water comes to a boil – that's all the fuel you need. The water can't get any hotter than 212 degrees (at sea level). So continuing to boil the water is both a waste of fuel and will also reduce the volume of liquid needed for re-hydrating.

To solve this problem, I was able to build a simple chart with a little experimentation that worked really well for my stove/windscreen setup.

1 cup 1 1/2 cups 2 cups 
30 degrees fuel amt fuel amtfuel amt
45 degrees fuel amtfuel amtfuel amt
60 degrees fuel amtfuel amtfuel amt
75 degrees fuel amtfuel amtfuel amt


I use a simple plastic measuring thimble with good markings and a squeeze bottle to get the right amount of DN. Using this chart, I can ballpark the temperature and get the stove fuel to run out at the precise moment the pot starts to boil. Doing things this way is probably safer (you won't be tempted to pull the pot off the stove when it's still full-flame) and you'll start hydrating your food quicker too.

As you experiment, you'll see that the amount of fuel is not linear which is why you can't simply double the fuel for 2 versus 1 cup of liquid. The reason being that (for my stove anyway) a portion of the fuel for DN stove is used for warming the alcohol until the "jet engine effect" can begin. I think this amount of "warming fuel" is fixed at any particular temperature so it'll be a higher percentage for smaller boiling volumes.

And to save even more weight, I used a permanent marker to put the chart on my freezer bag cozy!

This is a guest post from Steve Hanlon, an old friend, aka Hikezilla, who is a regular Section Hiker reader.

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  1. In your photo you have a priming pan. How do you account for the fuel needed to prime?

  2. I've only used the priming pan as a stabilizer. But you're right. All bets are off if I needed to use it.

  3. Thank you, SH. I see thru-hiking as a 4-dimensional puzzle, and appreciate your efforts to solve that puzzle more accurately. I hope you will share more of your experience with trail cooking.

    This is an auspicious occasion: Today my application for untaxed ethanol was approved, and they delivered my precious 2 liters of non-poisoned fuel. I mean to make the most of it.

    It's been a long time since I last carried a stove on my back, so I came to this part of the puzzle with a clean slate. It's nice that we choices, but alcohol fuel quickly showed itself to be the best choice in a spectrum of solids to liquids.

    Alcohol is like a solid fuel in that it takes a higher activation energy, and we can't throttle it. All we have for control is snuffing and initial supply. Your 2-dimensional method for calibrating fuel usage turns that bug into a feature. Well done.

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