Physics instructor Jason Thomas, also known as “Orbax,” spoke to The Weather Network for an explainer TV segment on how hand warmers work.

Orbax explained the chemistry and physics at work inside those little packets, which he said is made up of iron powder along with salt, activated charcoal and vermiculite.

“There is an intricate chemical process that takes place inside these bags. The process is oxidation — basically rusting,” he said.

Orbax, who does external outreach for the Department of Physics, recently helped U of G Physics and Astronomy Club set a Guinness World Record for the largest-ever creation of “elephant toothpaste” – a frothy explosion of chemicals that created a huge pile of foam on the lawn of Johnston Green last May.

Watch the segment below: