Why You Should Never Microwave Disposable Hand Warmers To Reuse Them

It's winter. It's freezing. You've forgotten your mittens, or worse, it's so cold your mittens aren't enough to keep your fingers warm. You have visions of frostbite. You find yourself wondering how many fingers a person can lose before their dexterity starts to go, too.

We've all been there, which is why the invention of disposable hand warmers was such a step forward. Disposable hand warmers, which are sometimes known by brand names like Hot Hands, work because of chemical reactions that occur when the packet is exposed to air, according to Hot Hands Direct. Each bag contains various compounds, including salt, charcoal, and iron. Opening a disposable hand warmer exposes its contents to the air, triggering a process called oxidation, in which the chemicals react with oxygen. As a side effect of the reaction, heat is produced, which is then released by the disposable hand warming packets, allowing them to warm your frigid fingers. Though the exact shelf life of disposable hand warmers can vary according to brand and weather conditions, Hot Hands estimates that their disposable hand warmers should keep producing heat for around 18 hours.

Though 18 hours is a long time, you might find yourself pressing up on that time limit and still be in need of something to warm your hands. What then? Some people might think the natural step would be to microwave their disposable hand warmers to give them a kick. However, this is very dangerous. Because disposable hand warmers contain chemicals, heating them up in the microwave can actually trigger an explosion, according to Question and Answer. This means you should never microwave disposable hand warmers.

However, there are other strategies you can adopt to make sure you're getting the most out of your hand warmers. For example, if you're finding you only need your hand warmers for a few hours at a time, you can actually pause the chemical heating process so that you can reuse the warmer on another day, according to Hot Hands. Simply put the warmer into an airtight container or bag. The lack of fresh oxygen will halt the oxidation process, and the warmer will cool off. Then, when you're ready to use it again, simply take out the warmer and expose it to air, and it'll begin to heat up once more.

Another alternative to reusing disposable hand warmers is to create your own reusable hand warmers. Many reusable hand warmers can be made out of items you likely already have around your house. For example, reusable hand warmers can be made out of uncooked rice (via I Can Sew This). In order to make these hand warmers, you just need a non-synthetic fabric, like cotton, as well as rice or other fillings, like uncooked corn kernels. Simply make pockets out of your fabric and fill them with your rice or corn. Then, when you're ready to use them, microwave the bags for 20 to 30 seconds, or until they're hot.

These hand warmers only stay warm for around 20 minutes, so they're not necessarily great for long walks in the cold. However, they can work as a substitute for disposable hand warmers in a pinch. And using these reusable hand warmers is always a safer option than microwaving disposable hand warmers and risking an explosion.