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Wonder Warmers Instantly Active Hand Warmers

Wonder Warmers Reusable Hand Warmers
Wonder Warmers Reusable Hand Warmers

Recently, I was pleased to find Wonder Warmers hand warmers, the current incarnation of a product I remembered from decades ago. You can use them as you would Grabber or Little Hotties dry-style hand warmers, however their heating process is completely different so that they have distinct advantages and drawbacks.

Wonder Warmers are pouches filled with a super-saturated salt solution which heat instantly when you press the metal activating disk within the pouch. The activating disk triggers the crystallization (actually freezing)  of the solution and this releases heat.  It is fun to watch as they freeze and get warm. They heat to about 130 F, slightly cooler than the dry-style warmers. However there is no waiting they heat immediately unlike dry warmers which take 20 to 30 minutes to fully heat.

They are also infinitely reusable, which considering the price is a good thing. You can recharge these warmers by boiling until all the crystals disappear and they become liquid again. Unlike dry-style warmers you can also use them in situations where they may get wet; this does not affect their heating ability. For example, you could use them inside a wet suit while kayaking.

Sadly, the drawbacks soon became apparent. The medium hand warmers (the model I tested) stay warm for only 30-40 minutes. You can extend this somewhat by keeping them well insulated. Also, the recharge process requires that you first wrap the warmers in cloth to protect them from direct contact with the bottom of the pot which could melt the plastic pouch. You must boil them for at least a full ten minutes at a rolling boil to ensure that all the crystals are gone. This is fine in the comfort of my kitchen, but I would hate to recharge these warmers over a camp stove.  Finally, they are heavy. The medium warmers weigh just short of 1/2 a pound at 7.9 ounces.

Wonder warmers seem like a useful option when immediate heat is crucial, the warmers may get wet, weight is not important, and you don’t plan to recharge while camping. I can imagine using them for canoeing or kayaking, while skiing, or while day hiking or car camping. However, the dry-style warmers win out for extended backpacking trips.

About Captain Mouse

Captain Mouse is a professional writer and editor who knows an enormous amount about hiking and backpacking gear, despite the fact that she hates to sweat. She is looking for new clients, so if you need an outdoor literate editor for a magazine article, book, or online publication, let me know and I’ll put you in touch with her.


  1. I had an employee who had a set of those about twenty years ago. We played with them to no end. It was really cool to play with… or maybe it was hot fun, I don’t know. A shock sets off the heat releasing freezing in the super saturated mix, hence the little bendable metal button inside. Slapping them really hard sometimes does the trick as well.

    Liquids on the verge of instability do some strange things. The first time I took my grandson backpacking when he was four, it was 18ºF when we got up in the morning. I had a two liter water bottle outside the tent and was surprised to find the water was liquid–until I cracked open the cap. When I did so, it instantly turned into pea size ice balls. I poured the rattling contents into the JetBoil to melt and heat up for breakfast.

  2. Great review! I tried those out a few years ago, because I was impressed that they were re-usable, but still use the disposable heat packs for a few reasons (in addition to the ones you mentioned:

    They are somewhat fragile – if the activating disk gets pushed accidentally, the solution crystalizes up, and starts the ~30 minutes of heat. It’s not something I would be comfortable cramming into a pack.

    Not as easy to use multiple days (but less wastefull). It was getting to be a pain boiling the pads after each use, when you can just grab a cheap pack of disposable warmers and they’re ready to go. Plus, It seemed like a lot of work for not much return, where 10 minutes of boiling gives 30 min of heat.

    Like you said, it’s really cool to watch the crystalization. I can see kids having fun watching it “freeze up” and they’re slightly safer for them because they don’t get as hot.

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