The Science of Sipping Coffee... The Art of Making Mugs...

How Good Design Gets Coffee Down Your Gullet on the Go

Modern humans make the simple task of drinking a hot morning beverage a challenge for industrial designers.

You want our morning beverage hot, and you want it to stay that way for much longer than is reasonable to expect. You need to drink it with one hand because the other is steering the car, hailing a cab, or holding on while the train whips you into another passenger. Meanwhile, you want to sip your brain-jogging juice without spilling it down the front of your work shirt. Why are you so demanding?

It's O.K. Good design makes it all doable.

Let's start from the mega important top of your travel coffee mug. A good lid will create a seal between the cap and the cup that remains sealed against jostling as well as being tipped horizontal. Approaches vary, but a lid with silicone gaskets usually does the trick.

The next concern is the vent. Without one, a drinking hole turns into a blowhole. "If it's sealed properly but it doesn't have a vent, it could end up spraying someone in the face," explains Francoise Vielot, a senior product manager at OXO. Like with a pressure cooker, steam with nowhere to go will build up in the cup. When there's only one hole, the steam escapes, sometimes violently taking the coffee with it. In addition to an outlet that delivers liquid (which we'll get to later), the cup needs to have a place to let off steam-but not too much, because it's also a gateway for outside air.

If you don't get sprayed in the face, just one hole makes the liquid hiccup on the way out because the cup is attempting to purge its contents and suck up air simultaneously. With two, the liquid and gas work together.

So now, you have a place to drink from, but getting liquid down your throat while swinging a bag, an iPad, and yourself around a corner without burns or stains demands even more of your portable mug.

The liquid needs to be regulated as it pours, or you could end up with a majorly burnt tongue (or a spill). You chug a beer, but you do not chug nearly boiling English Breakfast. There are a couple of ways your mug on the go helps deliver your coffee safely. First, the opening is typically recessed. This creates a landing where liquid gets a momentary shot of air before it reaches your mouth. As Thermos marketing manager Kim Flanagan explains, "How the liquid comes through the lid matters."

A properly sized drinking hole plays a big part in regulating liquid as well. Before launching their line of travel mugs, OXO did a lot of research into the "optimal sipping volume" for piping hot beverages. They found that plastic tear away lids let in more liquid than people preferred. "The length more than the width was not ideal," explains OXO's Vielot. Eventually they determined the perfect sized exit, which was smaller than the tear-aways but a bit rounder than the average Starbucks to-go variety.

The hope, of course, is that once you finally get the coffee where it needs to go, it's still hot when it gets there. Double walled mugs help achieve this by creating a gap between the outside air and the stuff inside the cup. But air between the interior and exterior walls will still conduct the hot or cold. So if you're really serious about temperature, you'll go with vacuum-sealed stainless steel - the removal of that air between walls blocks the transfer of heat across the divide.

That leaves the lid as the main culprit behind a temperature change. The smaller the top, especially for vacuum-sealed varieties, the less opportunity heat has to escape. So, sure, you want a mug that will fit snugly your car's cup holder, but, as Thermos' Flanagan explains, "having the mug tall and thin will allow it to actually hold the temperature longer." The shape also makes coffee-slinging doable with one hand-an absolute necessity for commuters.

When the design is good, the whole experience should be easy to swallow.

By Rachel Swaby