This provides fodder for fun jabs and inside jokes, but it did get me wondering: Why do coffee and tea stain all my mugs, and why are the stains so hard to get rid of? With these questions in mind ...

Time to find out. Without needing much encouragement, I volunteered to try out Ninja’s new coffee mug with Heatstore technology to discover if the wizardry worked. Here's how I got on.

They’re also more convenient — I make my coffee and tea at home the vast majority of the time, but now, I pour it into one of the few reusable mugs I tested for this story whenever I want to ...