We’ve all been there: It’s seven in the morning, and your sleepy brain desperately needs caffeine—like five minutes ago. But, as the label on your cuppa warns, drinking your Starbucks right away is sure to leave your tongue scalding. (Let’s not forget the infamous hot coffee lawsuit.) You’ve tried blowing on the steam; you’ve tried waiting patiently. Yet it seems as though you’re at the mercy of your burning hot cup of java. What to do?
Fortunately, we’ve found the fastest way to get your coffee to a drinkable temp—and it really works! Wait for it…just take the lid off, and in seconds you’ll be ready to drink up.
While that might sound self-evident, there is, in fact, a detailed scientific explanation behind it: Removing the lid from your coffee cup allows the hottest water molecules to escape through evaporation. Unlike heat conduction, which transfers the coffee’s heat to anything that’s colder, cooling by evaporation gets rid of that thermal energy much faster.
“As water on the surface of the coffee evaporates, it leaves behind lower energy water molecules, resulting in a lower coffee temperature. Without a lid, the cup provides a large surface area for evaporation—and thus cooling,” writes Rhett Allain for wired.com.
Allain even proved it through a homemade experiment. He found that the coffee without the lid cooled nearly two times faster than blowing on a standard coffee mug with the lid or leaving it completely alone.
If you want to keep your morning brew warm, here’s an extra little tip: Putting a plug in the lid of the coffee won’t keep the heat in as you go about your day. Apparently, the sole purpose of those little plastic sticks is to keep the coffee from spilling—not to trap in the warmth. Try pouring your coffee into a thermal mug instead to keep it warm all day long and avoid that stale, re-heated taste.
Prefer to get your caffeine fix from home? Check out the five tricks for making the perfect cup of coffee.