Cooking With A Thermos Bottle (Can It Really Be Done?)

cook in a Thermos bottleI first learned of Thermos cooking while reading Kurt Saxon’s The Survivor newsletter back in the late 1980s and have been using this thermal cooking method to save propane ever since. I have no way of knowing for sure, but I would estimate a savings of $40 to $50 per year from my doing this.

In a grid-down situation, using less fuel will be a top priority, and cooking with a Thermos (or other insulated vacuum bottle) will help you get the most from the smallest amount of fuel possible.

  1. All you’ll need is a small-mouth vacuum bottle (I prefer the Stanley vacuum bottle) and a funnel. Let’s take a closer look at how to cook this way.
  2. Start by preheating the vacuum bottle. Simply bring enough water to a boil to fill the bottle, screw on the cap, and set the bottle aside while you do the following steps.
  3. Heat the food in a pot on your stove until it is boiling
  4. Pour out the water used to preheat the vacuum bottle.
  5. Using your funnel so you don’t waste any, pour the boiling food into your preheated bottle, and let the heat inside finish the cooking.

That’s it . . . Simple, isn’t it? Here are several tips to make it even more energy efficient…

  • Lay the bottle on its side so the food will cook more evenly.
  • Wrap the bottle in a blanket to retain more heat.
  • I recommend a small-mouth Stanley (formerly Aladdin Stanley) bottle and not some cheap knockoff. But if you do get another type of bottle, be sure it has stainless steel insulation inside and not glass.
  • A gallon plastic bottle (e.g., milk, bleach, vegetable oil) cut in half makes an excellent free funnel. Just make sure it’s clean.
  • Shake the bottle every few hours so the contents don’t coagulate or stick to the sides.

Cooking time depends on what you are cooking, the type of insulated bottle you use, and the amount of preparation you do before adding the food to the bottle. You’ll learn by doing. But don’t get in any hurry, because your food will not burn or be overcooked.

You’re probably wondering what foods you can cook in a Thermos bottle. I cook whole-wheat breakfast cereal, steel-cut whole oats, rice, beans, lentils, and pasta. One of my favorite dishes is rice with chopped vegetables.

Thermal Cooking Without A Bottle

Thermal cooking can be done without using a vacuum bottle. This method is more convenient when cooking larger amounts of food, such as for beans. Thermal-Cooked Beans You need a large pot with a tight-fitting lid, a wool blanket, and a cooler with lid.

  • Sort and presoak beans overnight…
  • Bring the contents to a rolling boil for about 10 minutes, cover the pot with the lid, and quickly remove the pot from the heat and wrap it tightly in the wool blanket. Cover the pot completely because you don’t want any heat to escape…
  • Carefully set the wrapped pot of beans into the cooler, filling any remaining space between the cooler and blanket with the insulating material (e.g., old newspaper), and place the lid on the cooler.

Pinto beans take approximately three to five hours to cook this way.

If the beans are not done to your liking, simply reheat, rewrap, and let stand for another hour – this is also the case with thermos bottle cooking. 

Thermal cooking can be used to cook anything that you normally slow cook.

The advantages of thermal cooking are numerous: you get three hours of cooking time for only 10 minutes of fuel; food does not stick or burn if left unattended; water use is minimal because it does not boil away or need to be refilled while cooking. In short, thermal cooking is the most cost-effective and least labor-intensive method I know.

Note: Some of you may have heard about “cooler corn,” where you put raw corn on the cob in an insulated picnic-type cooler and then fill the cooler with boiling water. Then a couple of hours or so later (it keeps just right for a long time), you have corn on the cob.

The problem is that “cooler” plastics are made to take cold, not heat, and they may leach bad plasticizing chemicals into the cooking water at high temperatures. Now, if you have one of the old aluminum-lined Coleman coolers, you’re OK to cook this way.

M.D. Creekmore

I've been interested in self-reliance topics for over 25 years. I’m the author of four books that you can find here. Over the years, I’ve learned a lot about prepping, homesteading, and self-reliance topics through first-hand experience and now I want to share what I’ve learned with you.

7 Responses

  1. Greg M. says:

    M.D., thanks for this. I had seen this method posted (probably on your old site) a long time ago but did not record or print the article. Thank you for the review.

  2. Docj says:

    Thank You, MD. I needed the reminder.

  3. Jack says:

    We use a modification of this idea in my kid’s school emergency bags and for general camping. Some of our cookpots have a homemade cozy that works really well. For example, you can take off the rice before it is finished, place the pot in a cozy and it will finish off perfectly with no burned rice on the pot bottom. Less wasted food, less energy to cook, I like it! Now, as you may well guess, noodles of many kinds are a huge comfort food here in the Philippines. We have many brands to choose from and some are very high quality. Food safe plastic (we prefer double wall stainless steel) hot food containers work very well to reconstitute instant noodles and cook the other types that need a bit more time. While the noodles are doing their thing in the insulated container, canned shredded or chunk chicken or other canned meats are opened and added to the container. Presto, in a few minutes time our twelve and ten-year-olds are able to prepare a hot meal that they actually like and will eat. We do NOT allow our six year old to have fire starting tools, his own knife unsupervised or to cook hot foods due to the danger of a burn. His older siblings are trained to cook for him in an emergency situation. Six-year-old Christian’s bag does hold spare clothes, food items, snacks, sleeping gear, bottled water and small toys and entertainment items for comfort. Naturally, Christin also has safe light sources, signal whistle and a very basic first aid kit of his own stocked with items he knows how to use. We are happy with the progress our little ones show caring for each other and working as a team during each practice session. All these small things, even simpler ways to cook, do add to the symbiotic workings of our brood. Good post, MD and I certainly hope many folks will try this method for themselves.

  4. Frank Vazquez says:

    I also first learned about thermos cooking from reading that old Kurt Saxon article. I always thought it was clever and he mentioned how inexpensive it was and how he could enjoy a nice hot meal instead of a cold lunch or dinner.

    They have a name for it like residual radiation cooking, but the concept is to create heat, make it last as long as possible by preventing it’s immediate loss and allowing it to transfer to the food until it’s totally absorbed and begins to diminish. The pot in a blanket trick demonstrates this. I don’t own one, but I read that those old popcorn pans were used to warm beds as the popcorn cooked, but some people used shallow pans with lids.
    I remember my parents would wrap a pot in a blanket to take to a party or an outing and put it in the car’s trunk. It would stay hot for a while.

    A neat idea might be a project video or article on making a well insulated box to keep a pot of food hot. This way one can feed a family or group of people.