The worst part about drinking coffee? When it’s gone. The second worst? When hot coffee turns lukewarm. The “freshen-up” only kicks that can down the road so far; what’s needed is indisputable proof of what kind of cup keeps coffee hotter, longer.
Of course, it’s difficult to combat the mountains of anecdotal findings from your friends and family on the matter. Grandpa has been drinking joe out of the same metallic cup since the war, and he’s not complained. Your significant other is adamant coffee is better in their alma mater’s mug. And your sister swears by her stainless steel Contigo tumbler. And chances are, you’re more than partial to a cup that you like for no discernible reason whatsoever.
Where nostalgia and familiarity don’t carry the day, there’s room for a couple of objective factors to inform which coffee cup is best suited to maintain optimal temperature, longer. In scientific terms, you’re looking for the cup made from material that conducts heat least effectively. Meaning, you want something that will keep the heat inside, not transfer it out of the cup.
With that in mind, right away we know some materials will work better than others for coffee. Single-layer metal, especially containing aluminum, will transfer heat out of your cup fairly quickly. The key to keeping coffee hotter, longer, is...air. Air provides a strong insulator against heat transfer, and keeps the contents of your cup from losing temperature. Which is why your metal, insulated thermos is probably the best bet for keeping coffee hotter, longer, especially if you’re traveling with your java. Surprisingly, air insulation is also at play in the cardboard sleeve most coffee shops place around their paper cups. Aside from keeping your hand from being burned (yeah, paper doesn’t insulate that well), the cardboard is usually fashioned in such a way to form air pockets around the cup, keeping the heat in longer.
At home, ceramic mugs are the common go-to for coffee consumption, but they may not be the most effective receptacle for keeping your joe hot. According to at least one test, that distinction belongs to the plain ol’ styrofoam cup. The reason, again, goes back to the air - the styrofoam contains many pockets of air that help provide insulation. As most of us know, ceramic mugs are still effective, however. And they make for a much more interesting table setting. One piece of anecdotal advice: Prime the cup before pouring your coffee by filling it with hot tap water, and letting it sit for a few minutes. It will give you a few more minutes of drinking at prime coffee temperature.So until everyone has a mug developed by scientists to keep coffee in the “ahh” zone, it’s best to consider the makeup of the cups we use for our favorite beverage. It will make for a more pleasant beverage experience...if you’re looking to replace that old mug, that is.