“My hands are cold, my feet are cold because of the cold winter wind.” This is a part of a Korean children’s song named “Winter Wind.” As the lyrics say, the winter wind tries to get in between thick coats and muffler. It is not easy to get through the cold winter. Therefore, people developed portable heaters, or, more specifically, hand-warmers. Let’s find out more about hand-warmers, a necessity to get through winter.
Hand-warmers in Your School Days.
1. Button Hand-warmer
Do you remember the hand-warmer that you saw in stationery stores in your school days? It had a button. As you know, when you pressed the button, the hand-warmer became white and hardened, emitting heat. Maybe this hand-warmer was a necessity for getting through winter in your childhood.
- Principle: There is a supersaturated sodium acetic acid solution in the button hand-warmer. This solution is hardened during the emission of heat, when you give impact to the solution. Through absorbing heat, the sodium acetic acid melts. In other words, it uses melting and congelation concepts.
① This is semi-permanently reusable. When you heat the hardened button hand-warmer in hot water, it restores its original state.
② It is convenient to carry.
① It maintains the heat for a short time.
② The cover can be damaged during the emission of heat and you can burn yourself with the content.
③ If you sniff the acetic sodium acid, which is one of the ingredients of the button hand-warmer, it causes difficulty in breathing and stomachache.
2. Shaking Hand-warmer
This hand-warmer is also called a “hot pack.” You can also easily get it at a stationery store. This is commonly used for winter camping, the army and so on.
- Principle: The contents of the hot pack are shaved iron, salt, a little water, and activated carbon. It uses heat, which occurs when iron is oxidized. This oxidation reaction is very slow. Salt and activated carbon function as catalysts that speed the oxidation reaction up. When you tear off the paper bag and knead or shake the hand-warmer, the shaved iron causes a very fast oxidation reaction because it is exposed to oxygen. In that case, its temperature rises from 30℃ to 60℃ within several minutes.
① It maintains the heat for a long time. It keeps the heat for at least 10 hours.
② It is easy and comfortable to use.
③ It can be used in a range of ways because it has a variety of sizes.
① It is a one-time hand-warmer.
② You can get low temperature burns.
*Low temperature burn: A low temperature burn occurs at relatively low temperature (approximately 40℃ to 60℃).
*Sticky hot pack
This has the same principle as the hot pack and even the contents are the same. The difference is that this hot pack doesn’t need to be shaken or kneaded. Since this hot pack is thin, it reacts to air directly.
Recently, people developed so many kinds of hand-warmers like USB hand-warmers, oil hand-warmers, and eco hand-warmers. Let’s find out about them.
1. USB Hand-warmer VS Oil Hand-warmer
The USB hand-warmer is a very innovative product. This hand-warmer supplements a button hand-warmer and hot pack. It uses a battery that can be charged by USB cable, so it is reusable and can control the temperature maintenance time. However, this hand- warmer also has disadvantages. The temperature is low compared to others. In addition, if the USB hand-warmer is not charged, you can’t use this while outdoors. Therefore, an oil hand-warmer was developed to work around the disadvantage of USB hand-warmers. An oil hand-warmer uses a battery that can be charged by lighter oil. The temperature is high. If you have lighter oil, you can use it everywhere, every time. However, it also has disadvantages. When you use this for a long time, you have to buy lighter oil continuously, so costs of maintenance are higher than those of USB hand-warmers. It can smell of oil and it has some risk of fire, too.
2. Eco Hand-warmer
Eco hand-warmers with a cute character shape use grains without chemical substances or batteries. You can heat them up in the microwave. This hand-warmer is eco-friendly and reusable and has no toxic substance. However, it maintains the heat for a short time and when you don’t have a microwave around, you can’t use it.
You can make a hand-warmer using grains in your home. First, prepare a pocket made of cloth or a woolen sock. Second, put some grain like wheat, soy, red beans or rice in the pocket or sock and sew closed the entrance. Finally, heat it up in microwave.
Lately, hand-warmers are not just ”hand” warmers. With technological advancement, hand-warmers’ forms are diversifying. Heat gloves and heat slippers using USB cables are examples of this. These products are very useful when you work on a computer in the cold winter. Besides, heated innerwear, heated vests and heating pads can help keep out the cold.
It is good to give hand-warmers as a gift for a person who is sensitive to cold. However, if there is something warmer than the hand-warmer, it’s a person’s hand. Holding hands makes not only someone’s hands warm, but also their heart. How about sharing a warm heart by holding the hands of someone next to you right now?