Do Hand Warmers Work After Expiry Date?

A hand warmer is a small disposable packet that produces heat on its own to warm the hands when they get cold. It is an air-driven, convenient, efficient, and portable source of heat that requires no external force to operate. When it’s cold, it works like magic to keep your cold hands warm, but does it continue to keep your hands warm after it expires?

In most cases, hand warmers still function after expiration if they are stored correctly. However, there will be a slight difference in its functionality, such as longer heating time or may not heat like an unexpired hand warmer. Even though hand warmers continue to function after they expire, it is always advisable to bring along an additional, hot hand warmer that hasn’t expired for every one that has.

How Do Hand Warmers Work?

A hand warmer contains a disposable pouch packet in an airtight packet. There are different types of hand warmers that function differently but mostly it contains salt, activated carbon, water, iron and an absorbed material.

As soon as the pouch is removed from its outer packaging the oxygen reacts with the iron powder inside in the presence of salt and water (oxidation) to produce iron oxide (Fe2O3) which in result generates heat. Meanwhile activated carbon aids in the equal distribution of heat, while absorbent materials like vermiculite aid in the retention of water content.

Because the entire reaction depends on exposure to air, it functions properly in an environment that is well-aerated. The main mechanism of hand warmers is the rusting of iron which produces heat.

What is the Shelf Life of Hand Warmers?

The shelf life of hand warmers varies on its storage but it typically remains intact for three to four years when unopened. Once the packet is opened, it will remain usable until the iron powder has completely oxidised, at which point it will be thrown out. Protecting the hand warmers from direct air contact is essential to extending its shelf life because oxygen will initiate the oxidation reaction.

Some hand warmer packaging may fail to prevent air contact, so it is best to store your hand warmers in an airtight container or bag if you intend to use them for an extended period of time.

We Recommend the Following Warmers

1. HotHands Hand Warmers

2. Sport Temp Large Hand and Body Warmers

3. Hot Hands Hand Warmers - 11 Hours Lasting

The natural rusting process is used by hand warmers to generate heat on the go. In the presence of moisture and salts, it initiates the oxidation reaction with the aid of iron and oxygen to generate heat. Its functionality may suffer slightly after its expiration, but it still works in some cases. The lifespan of hand warmers varies depending on how they are stored.