The 10 Best Thermoses
10. Corkcicle Canteen
9. Coleman Bottle
8. Thermos Rock
7. Zojirushi Tuff
6. Thermos King Food
5. Vremi Mug
4. Thermos Vacuum 16 ounce
3. Stansport Shotshell
2. Nissan Hydration
1. Thermos King
Keep Your Molecules Shaking
I remember the first time I encountered a thermos. I was in the parking lot of Six Flags Great Adventure in southern New Jersey, on a trip to the park with my best friend's family. We sat on lawn chairs they'd packed into the vehicle, and my buddy's mom brought out this thing that looked like a fat little pitcher, except it had an upside down mug on top of it.
When she opened it, steam poured out along with the vexing aroma of cooked hot dogs. This was the fatter type of thermos that's ideal for transporting food, and it contained a dozen dogs she's cooked just that morning.
It would be another 20 years before I discovered the principals and technology that allowed those dogs to stay so hot all morning. For the longest time I figured it had something to do with the seal at the top of the container, that it somehow kept the heat in all by itself. Little did I know that there was a miracle of science happening in the chubby little food bottle.
Let's start at the beginning, though. How did the hot dogs get hot in the first place? Well, when an energy transfer causes the molecules in a given substance to become excited, they move at an accelerated pace, heating them up. Both the dogs and the water in which they were boiled took the energy transferred into them from the flame on the stove and their molecules went bonkers.
Then, my buddy's mom put them inside the thermos, which works on a very simple rule of thermodynamics: a vacuum is the best insulator. That's because heat energy can't transverse a vacuum since there are no molecules therein for the energy to excite. Infrared radiation can make the jump across a vacuum, however, which is why your thermos still feels a little warm to the touch, and is one of two reasons why your thermos eventually loses heat.
It is true that a few years ago, a handful of scientists designed a thermos with a vacuum that included a lining of very finely tuned photonic crystals, and that that prototype also blocked the infrared radiation from escaping, essentially doubling the prototype's insulating power. The only problem there is that each thermos made with photonic crystals would be prohibitively expensive.
An Honest Evaluation
There are a lot of industries out there that seem to thrive on inflating the statistics and capabilities of their products. Thermoses, somehow, have avoided this pitfall of cut-throat capitalism. Every thermos I've ever owned has kept its contents hot or cold for as long as–and often longer than–the company claimed it would.
What that means for you is that you have three simple variables to consider when moving along our list. First among them is that preservation time. You'll notice that its easier for a thermos to keep a substance cold for longer periods of time than it can keep them hot, and that's pretty normal. Whatever the claims, you ought to be able to take them at face value, so reach for something that can keep your food or drinks where you want them for as long as you might need.
Secondly, you want to consider capacity. There's not much reason to keep only a morning's worth of coffee hot if you're going to need energy all day. I lived out of the biggest thermos on this list at a job up in Alaska for a whole summer, filling it up with black gold each morning and drinking it down, hot and delicious, throughout the day.
Finally, there's style to consider. If you're getting a thermos as a gift for the gruff construction worker in the family, the Hello Kitty themed container might not be his first choice. It would suit your young niece a lot better than the industrial Stanley models, though.
One last note: be careful with your thermos. The majority of thermal vacuums rely on glass or ceramics for their walls, and a tough drop can crack the material, causing a steep decrease in preservation times.
How Do You Dewar?
In the late 1800s, a Scottish scientists named James Dewar created a partial vacuum between two brass chambers to insulate palladium in an attempt to determine the element's natural heat. In doing so, he invented the first vacuum flask, which gained tremendous popularity in the scientific community.
By 1904, a pair of German glass blowers took Dewar's idea, which he never bothered to patent, and commercialized its design, creating a consumer-friendly product that anyone could use to keep food and drinks hot or cold. They were the first purveyors of the vacuum flask to use the term Thermos in regarding and marketing the item.
For a time, the thermos was an integral part of the American child's lunchbox, sharing a themed design with the one printed on the outside of the box. They became important parts of synergistic marketing methods employed by the entertainment industry in the 1980s and 1990s. There was a brief dip in interest in the thermos, but as the generation of children who grew up with the devices in their daily lunch kits has kids of its own, use of the thermos is back on the rise.