Before we get started, it's worth mentioning that not all hand warmers are created equal, nor do they work in the same way. Knowing about how does a hand warmer work allows us to discern the risks and benefits of any one, and it allows us to make informed decisions about which types we want to spend our money on and which ones we'd rather avoid.
TYPES OF HAND WARMERS
The four most common types of hand warmers on the market are:
- Lighter fuel
Air-activated Hand Warmer
Air-activated Hand Warmer typically contains iron powder, water, salt, activated charcoal, and vermiculite. And how does an air-activated hand warmer work? Once removed from the airtight packaging and exposed to the air, the hand warmer will begin to heat up. Iron is oxidized, forming rust (iron oxide/hydroxide) and giving off heat. This process is indeed the same as the rusting of iron that you may observe in everyday life. Under normal conditions, however, iron rusts much more slowly, so the heat released is rarely noticed.
Generally speaking, 1 gram of iron can release 1.7 kcal of heat. Powdered air-activated hand warmer can get very hot, so direct skin contact should be avoided. Now you knew the principles of ''how does an air-activated hand warmer work'', so if you want to keep a hand warmer that's still warm for later, reducing exposure to air may help slow oxidation. You might try sealing it in an airtight zip-lock bag to prolong its life. However, if you want your air-activated hand warmer to be hotter, you can speed up the oxidation by shaking the iron dust bag to improve air circulation. No matter what you do, once the oxidation is complete, the air-activated hand warmer will stop heating and can no longer be used.
Crystallization-based Hand Warmer
The second type is a crystallization-based hand warmer. Lots of people bought this kind of hand warmer, but how does a crystallization-based hand warm work? Such a hand warmer is usually a sealed bag of chemicals in the form of a supersaturated sodium acetate solution with a small metal chip inside. Supersaturation means that the solvent contains more of the dissolved substance (solute) than it can normally hold at the given temperature.
When you flex the metal chip, nucleation occurs at the chip surface and the solution crystallizes, releasing heat. Having know ''how does an crystallization-based hand warmer work'', if you want to reuse the warmer, simply heat it in hot water and dissolve the crystals again. They can be used over and over again, which is why some people consider them a more environmental-friendly option than the air-activated hand warmer. Crystallization-based warmers are easy to use and recharge, but their heating time is usually shorter than air-activated ones.
Battery-powered Hand Warmer
Battery-powered rechargeable hand warmers are fairly straightforward from a functionality standpoint, though the actual science behind how a battery-powered rechargeable hand warmer work is more complicated. In them, a rechargeable battery sends power to an onboard electrically resistive heating device, which converts that energy into heat, and the level of heat is fixed.
Although knowing how a battery-powered rechargeable hand warmer work is more complicated for us, with the Ocoopa Union 5s rechargeable hand warmer, you would get a simpler but better experience. It comes with 4-level adjustable heat enhancing the hand-warming experience. You can select the level of heat put out by the hand warmer. Then, once the battery is spent, all you have to do is plug it in and charge it back up for subsequent use. The rechargeable battery core enables you to refill your hand warmer for another 15 hours of use anywhere and anytime outdoors.
Lighter fuel Hand Warmer
How does the lighter fuel hand warmer work? It houses a lighter reservoir - with a strange cotton-like mesh inside - that needs to be topped up before the operation. Once the reservoir is filled, a "catalytic burner" unit is placed over it. The device draws fuel into it, which when exposed to fire (yes, you need a separate lighter or matches to start the reaction), starts the combustion process with no visible flame. You just put the cover back on top of it and you are free to place the heater wherever you want. It's worth noting that this type of heater produces carbon monoxide when burned, which can be dangerous -- though it shouldn't be a problem with good ventilation or outside.
Charcoal Hand Warmer
How does a hand warmer like charcoal hand warmer work? In order for a charcoal hand warmer to work, you have to actually burn the charcoal - just like a barbecue. The case itself is usually a felt-covered unit, shaped and formatted like a sunglasses case, made of metal (to dissipate heat without burning).
To make it work, you need to take a charcoal stick and tap the end of it to start the burning process, then places it inside the unit and turn it off. This is "how does a charcoal hand warmer work", it would fit securely in your pocket. The downside to this type of hand warmer is obvious: you have to burn charcoal. It's wasteful, dirty, and unsustainable. Plus, since it's actually burned, it produces carbon monoxide - which can be harmful to your health.
How to choose a suitable hand warmer
Having known about ''how does a hand warmer work", and the risks and benefits of those hand warmers. If you're not sure which ones to choose, you can consider how long you'll need them. For short commutes, you can go with an air-activated hand warmer or crystallization-based hand warmer.
But you consider getting a practical one for longer outdoor activities, go with a rechargeable warmer like Ocoopa. They are arguably the most economical from a cost-after-purchase angle and are the most environmentally friendly when it comes to usage. Also, these Ocoopa rechargeable hand warmers are great winter gifts for your friends and families because there are still plenty of cold winter nights even after Christmas.