Disposable hand warmers contain a mixture of iron, water, activated carbon, vermiculite, cellulose, and salt. Once exposed to air, the iron oxidizes and releases heat in the process.
In order for the reaction to occur, the hand warmer needs a supply of oxygen.
If you cut off the supply, the chemical reaction ceases.
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What are hand warmers?
Hand warmers are small pouches to hold in the hands to produce heat to warm up cold hands. They are mostly disposable, but some are reusable too. They are commonly used in outdoor activities. Few other types of warmers are available to distribute soothing heat for muscles or joint aches. Hand warmers can last up to 10 _13 hours depending on the type and the source of heat.
The hand and foot warmer was first invented by Jonathan T. Ellis of New Jersey in 1981. The first commercially- produced hand warmer was invented by a Japanese named Niichi Matoba.
He applied the principle of an oxidation reaction that produces heat by means of platinum catalysis. He then worked hard on this formula to reach a product for practical use. These portable hand warmers are still being produced in Japan.
Types of Hand Warmers
There are commonly 7 main types of hands warmer in the market which are:
- Air activated (iron)
- Supersaturated solution (crystallization-type)
- Lighter fuel
- Metal disk
- Sodium Acetate
Air Activated Hand Warmers
Air activated hand warmers contain cellulose, Iron, activated carbon, vermiculite (which holds water) and salt. The heat is produced from the oxidation of iron when exposed to air. It usually takes 15_30 minutes to start heating up and keep on emitting heat for 1_10 hours. The hand warmer needs the supply of oxygen to get a warm up start; if the supply is stopped, the reaction tends to cease.
Crystallization Hand Warmer
The crystallization- type of hand warmer can be recharged by dipping it in very hot water, just to help the contents inside the hand warmer to be uniformed: and then let it get cool. The heat is required to dissolve the salt in its own water of crystallization. Through this process instant heat is produced.
Lighter Fuel Hand Warmers
Lighter fuel hand-warmers contain lighter fluid called petroleum naphtha. These hand warmers generate heat for almost half a day. These can be reused by re-fueling the fluid.
Battery Operated Hand Warmers
Battery operated hand warmers use electric heating devices to convert energy into heat. These hand warmers can usually transmit heat to the hands for up to six hours.
Charcoal hand-warmers produce heat by burning charcoal in a special case. They are comfortably hot and spread the required heat equally to the hands.
Metal Disk Hand Warmer
The metal disk in the pouch gets bend; when you bend the hand, and the hand-warmer heats up. Bending the disk or the metal strip in the hand warmer solidifies the liquid inside. It results in an exothermic reaction: the heat is released. And this heat provides warmth to the hands. Heating the hot packs in a microwave works in a way that the metal disk is isolated from any other conductive items so the microwave energy has no effect on it.
Sodium Acetate Hand Warmer
The types of hand warmers that contain sodium acetate are reusable. These are ideal reusable hand-warmers for those who have to deal with having cold hands on a frequent basis throughout the season. The chemical reaction of these reusable hand warmers was discovered in 1978. The pack contains a solution called sodium acetate dissolved in water. The process of crystallization takes place when the ferrous metallic disc is bent. This disc releases tiny particles of sodium acetate into the solution. When the hand warmer is boiled, sodium acetate re-dissolves in the water, and this process starts at a temperature of 137 F and above.
Do hand warmers work in water?
All types of hand-warmers won’t work under water because they are air (oxygen) activated; simply can’t work under water.
What are Disposable Hand-Warmers?
There are disposable hand-warmers too which are easy to use with the only difference that after all the iron is done in the heating process, the hand-warmer is expired and is ready to throw away in the trash.
Disposable hand warmers heat your mittens by means of exothermic reaction. When the pouch, typically containing iron powder, salt, water, and activated carbon, is removed from its outer packaging, oxygen floats across the pouch’s permeable covering. With the salt and water present in the pouch, the oxygen reacts with the iron powder to form iron oxide and finally releases heat.
Do the hand warmers cause skin burns?
The chemical process in the hand-warmers is designed to keep the hands warm in extreme weathers, so you should never place warmers into direct contact with the skin. It might burn the skin.
It is always advised to avoid direct contact of the hand warmers for too long because it may lead to skin burns even if they are slightly warmer than the normal body temperature. Hold them directly for a couple of minutes at a time when they are at the highest temperature. In this way the hand warmers are safe to use: the contents and ingredients are non-hazardous and non-toxic.
Why and where to use hand-warmers?
Being able to keep your hands warm in the worst cold weather is a wonderful thing.
Anyone who fights with the cold temperatures is tempted to try the tiny disposable pouches or reusable hand-warmers that emit heat within seconds of being exposed to air.
What is the metal disk in hand warmers?
The metal disk inside the hand-warmer heats it up which provides warmth to your cold hands. When the disk bends, it causes the liquid inside the hand-warmer to solidify so this changes into an exothermic reaction.
How Does a Reusable Hand Warmer Work?
Reusable hand warmers use a sodium acetate which produce heat, it doesn’t contain iron. Not all hand warmers are reusable as air-activated hand warmers can’t be reused where the other hand warmers can be reused. For rescuing a hand warmer, you have to submerge it in the boiling water until the crystals turn to liquid.