What is a Thermos®?

Popular among campers, kids, and many employees who take lunches to work, the thermos is a simple device that is a vacuum flask that helps to maintain the temperature of the liquid stored within the container. More properly known as a Dewar’s flask, the thermos is actually a brand name for this style of flask, but over time has become the common designation for all devices of this type. Developed primarily for beverages, the thermos can also be used for soups, stews, and even cooked vegetables and servings of casseroles.

The classic Thermos vacuum flask was designed with a tempered glass interior that would keep cold beverages cold for several hours. Equipped with a small mouth and topped with a screw on cup, the device was an ideal means of taking along all sorts of beverages. The same properties would also maintain the temperature of hot beverages as well. This made the thermos an ideal way for adults to take along coffee on long drives or to a work site. School age children could also benefit from the thermos, since the flask would keep beverages cold until lunchtime.

Over time, thermoses were developed for other applications. Wide mouth thermos bottles could be used to take along a nourishing meal of soup or stew. Because the food would remain warm, it was also possible to use these versions of the thermos to take along servings of a casserole or cooked vegetables. These wide mouthed types could also be used to take along desserts, such as cobblers or gelatin and fruit combinations. The glass interiors were also replaced with tempered plastic blends that would not shatter if the device were accidentally dropped.

While the advents of vacuum packed meals and microwavable lunches cut into the market for many types of vacuum flasks, the traditional thermos for beverages continues to be a popular item. People will often take the thermos along for picnics, campouts and other outings, or as a simple way to take along hot chocolate of coffee when embarking on a long drive.