Home > News > Content
Is A Sodium Acetate Hand Warmer Safe? What Is The Science Behind It?
Jul 28, 2018

What Are Sodium Acetate Hand Warmers?

Being able to keep your hands nice and warm, even in the coldest conditions, is a wonderful thing. Gloves aren’t always enough – especially for those with an extreme sensitivity to cold. There are many types of hand warmers out there, but not all of them are reusable or contain sodium acetate (NaAc), which is a colourless deliquescent salt that has a variety of uses. Other types of heat packs rely on irreversible chemical reactions and can only be used once. They must be thrown away after just one use. Hand warmers that contain NaAc are reusable, making them ideal for individuals who have to deal with having cold hands on a frequent basis.

How Does the Science Work?

The chemical reaction associated with these reusable hand warmers was discovered in 1978. The packs contain a supersaturated solution of NaAc dissolved in water. The main action involves the process of crystallization, which is triggered when you snap or bend the ferrous metallic disc. When pressed, the disc releases tiny particles of NaAc into the solution. These minute crystals then act as nucleation sites that allow what is left of the sodium acetate solution to re-crystallize. Boiling the hand warmer re-dissolves the sodium acetate in the water, renewing the supersaturated solution. This process takes place at a temperature of 137 F and up. The process can be restarted when the warmer has been cooled to room temperature.

Are These Hand Warmers Safe?

Yes, although it’s recommended that you wrap them in a cloth when boiling them in water. Do not allow them to sit at the bottom of the pot, as they could be damaged. Also, don’t hold them directly on your skin for more than a couple of minutes at a time when they are at the highest temperature. As long as you follow directions, NaAc hand warmers are safe to use. The contents and ingredients are non-hazardous and non-toxic.

What are the Benefits of a Sodium Acetate Hand Warmer?

Some of the pros associated with these products include:

Re-usability

The ability to provide almost instantaneous heat within mere seconds of activation

Easy to clean and maintain

Self-regulating temperature

Can be used along with a wet towel to provide moist heat therapy

Portable, lightweight design

No risk of a fire

Provides at least thirty minutes of heat to the hands, fingers, and wrists

Even the larger hand warmers are lightweight compared to heating pads.